The Electric Way

The Electric Way

A brief history of electricity from the amber of the ancient Greeks to photovoltaic panels

Author: Enrico Halupca Translation: John Daer Editing: Sintesi srl Photo credits: Sintesi srl, Enrico Halupca Publisher: SSO – Svet slovenskih organizacij / Council of Slovenian Organizations Project manager: Ivo Corva © SSO – Trieste, 2020 This publication is available at the following link: www.lightingsolutions.org Publication financed under the Interreg V-A Italy Slovenia 2014-2020 Cooperation Programme, co-financed by the European Regional Development Fund.

The content of this publication does not necessarily reflect the official positions of the European Union. The responsibility for the content of this publication belongs to the publisher SSO.

The Electric Way A brief history of electricity from the amber of the ancient Greeks to photovoltaic panels

An irreplaceable resource

Phenomena as conspicuous and dazzling as the lightning bolt in the night sky that suddenly illuminates the surroundings before being followed by an ominous roar, or conversely, as absolutely microscopic and silent as the attraction of tiny straw fragments on an amber rod that can go unnoticed for millennia, can all be traced back to a single basic force that permeates the universe, electricity.

Electricity is today harnessed by our most advanced technology to make our world work in various contexts.

How could we work in our offices, universities, our advanced research centres, without electricity to power all the equipment we need to write, to communicate and to store useful information?

We could hardly do without our inseparable smartphone, which we carry around with us without ever turning it off, relying on the long-lasting rechargeable lithium batteries.

Without electricity, the entire industry would grind to a halt.

The Covid-19 emergency in 2020 showed that during the lock-down with the forced closure of businesses, electricity consumption fell by only 9% globally, much less than everyone expected.

The reason is that even our leisure time, which in our societies is largely taken after sunset, would be very difficult to manage by candlelight.

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Indoor and outdoor lighting is electric, with low energy LED technology gradually replacing energy-inefficient light bulbs.

Mobility, with the substitution of electric motors for fossil fuels, is increasingly complying with the Green Deal, the new energy course undertaken by Europe to avoid global warming, in the wake of international climate protection decisions (Kyoto Protocol, Paris Agreement) in preparation for the Glasgow Summit to be held in 2021.

Without fear of contradiction, it can be said that electricity has become by far the most important energy resource of our contemporary civilisation. An irreplaceable component of our highly technological world.

A basic necessity such as water has always been fundamental for our biological system. We could not do without either. They are fundamental and irreplaceable resources.

Today, more than ever, it has been realised that when this type of resource is scarce due to poor distribution, it leads to major social imbalances on a global scale.

In a globalised and interdependent world like ours, knowing how to make good use of these resources therefore becomes a fundamental ‘must’ for our common future.

A conscious use of electricity is of fundamental importance not only for the economy of a nation, but also for the shared well-being in terms of less pollution of the planet, reduction of global warming, restoration of the climate to natural values of variability.

But what is electricity?

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Come to think of it, for most of us, even though more or less 10 generations - 220 years - have passed since Alessandro Volta invented the electric battery, this invisible energy is still seen by most of us as being somewhat mysterious.

Certainly, from physics textbooks, after the discoveries of the early 1900s, we find very detailed explanations of what it is: Electricity is one of the fundamental properties of nature and is manifested through attractions or repulsions between bodies and derives from the atomic properties of matter”, “bodies endowed with this property are said to be electrically charged” and “those responsible for this charge are particles that are part of the atoms of matter, electrons, which carry a negative charge...” etc.

(TuttoFisica, De Agostini, 2019)

Many of us, even though we are familiar with these elementary concepts of physics, will still have asked ourselves some more or less complicated questions, even naive ones in some respects, without knowing whether the solution believed to be probably right was actually the correct one.

Let’s take a few examples with a series of questions I have asked myself: Why is there ‘static electricity’ and a ‘direct current’.

What is lightning, and why did Benjamin Franklin have to risk being electrocuted flying a kite? Why was a great genius like Nikola Tesla the first to think of transporting An irreplaceable resource

3

high-voltage electricity, and why did he design the first ‘alternating current’ dynamos instead of ‘direct current’ ones ? And how does the ‘alternating’ current we have in our homes today turn on a light bulb in a continuous flow ? Or drive an electric motor in one direction, if the flow of electrons in the circuit moves extremely fast between the two poles, at a rate of 50 vibrations per second here in Europe, to be exact? And why is the photovoltaic panel connected to an insight that Einstein had that predates the Theory of Relativity? And, why has the LED taken so long to be adopted as a source of lighting?

These are just a few examples among many that could be given.

This is why we need to know a little about the history of some of the basic elements, including through this simplified “Brief History of Electricity”, which will help us to find our way through the “FAQs” (frequently asked questions) that the more curious among us may ask.

You will certainly not find here a didactic manual with pre-packaged answers, but instead, an account of the historical path that has led, step by step, intuition by intuition, through the tireless work of the most brilliant minds, to the extraordinary technological transformation we are experiencing. Happy reading!

The author - Trieste, October 2020

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1 Inexplicable attractions

Petrus Peregrinus

THE DISCOVERY OF ELECTRICAL AND MAGNETIC PHENOMENA

T

he technology that harnesses electricity came into use relatively late in our world. Only in the 20th century, in a very short period of time, absolutely ‘disproportionate’ compared to the development of other technological solutions used by mankind throughout its millennial history.

For example, animal-powered traction, which has been in use for 5000-6000 years since the dawn of civilisation and of which we have archaeological knowledge, or hydraulic power, which was already known and used in Roman times, but was never adequately exploited and was even forgotten until almost the year 1000, when the advent of water mills spread throughout Europe, only to disappear again, this time for good, just after the Second World War. They were replaced by large steam-powered mills as early as the 19th century, then by internal combustion and electric mills.

Since the dawn of Western civilisation, some curious, apparently inexplicable phenomena have been observed in Nature. The attraction of iron by certain rocks was undoubtedly one of these phenomena that had to be explained because it seemed to be an exception to the normal rules of common sense.

According to a legend told by Pliny the Elder, a humble shepherd named Magnes noticed this anomaly in Greece many centuries ago. He used to walk steep, lonely paths to lead his flock to graze, and one day he decided to equip himself with a stick to which he had attached an iron ferrule and with sandals whose soles, reinforced with iron nails, would have more grip and would not wear out so The Electric Way

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quickly on those stony paths. However, when he reached a stretch of road where some shiny black rocks emerged, he noticed that his walking stick was being attracted to these strange rocks and no matter how hard he tried to walk faster, he just got tireder and tireder. His sandals inexplicably slowed him down instead of helping him along the path. A mysterious force was holding back his steps and once he had stopped, he could hardly lift his feet off the ground. Magnes thought that this black, shiny rock held a curse from the gods of the underworld, and panicking, he abandoned that stretch of path, leaving his sandals stuck on the treacherous ground. From then on, the black rock on which Magnes had ventured was called magnetite and all solid bodies with similar properties, ‘magnets’.

The Greek philosophers, observing the wonders of nature, discovered other very special phenomena of attraction that could not be attributed to the properties of magnets: in the writings of Aristotle it is reported that as early as the sixth century before Christ, in the time of Thales of Miletus (640 BC - 548 BC), another curious phenomenon was noticed: when rubbing a yellow amber object with a dry hand and quickly bringing it close to some pieces of straw, the straw was attracted to it and some of it was inexplicably repelled immediately afterwards. Why? This property, which we now know as static electricity, due to the rapid change of positive and negative electric charge caused by friction, was in fact very differently, structurally speaking, from the permanent magnetic fields in the magnet, but it took a long time to distinguish between the two phenomena which seemed to share Inexplicable attractions

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a single attractive force and, to fully understand the difference between electrical and magnetic phenomena.

We have to go back to the Middle Ages.

The properties of magnetised objects, which, if free to rotate, orient themselves spontaneously, were already known in China in the 1st century AD. Chinese sailors used a spoon-shaped instrument (si-nan-shao) as a compass, which, free to rotate on a bronze plate, pointed its handle to the south. In the West, sailors used a simple magnetised needle which, balanced on a vertical axis, pointed north in the absence of friction. It was first mentioned by the English canon Alexander Neckam (St Albans 1157 - Kempsey 1217). In 1190, in his De utensilibus, he strongly recommends carrying on board this simple, yet marvellous instrument, which is indispensable for finding the direction to head in when on the open sea, even if visibility is prohibitively poor, due to the weather: If one wishes his boat to be well provided for, then he

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must also have a needle mounted on a dart. The needle will swing and turn until it is heading north.

(De utensilibus, pribl. 1190)

But the first person to deal with the subject systematically was a man of exceptional observational skills, trained in French alchemical circles. His name was Pierre de Maricourt, but was universally known, after his travels in the Holy Land, as Petrus Peregrinus (13 th century AD).

Of his life we know little. That he was an alchemist in Inexplicable attractions

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search of the laws that regulate the transmutation of metals may seem strange to our modern eyes, but at the time we are talking about the distinction between the scientific, and the parascientific, does not make much sense as a distinction given that the Western scientific method was yet to be come. One spoke instead of natural philosophy. Another famous 13 th century alchemist, Roger Bacon (Ruggero Bacone in Italian), speaks of it with great admiration, pointing to the uncommon qualities of the man he considered his master of art and spirituality:

“What others grope for, like bats in the evening twilight, this man (Petrus Peregrinus) contemplates in full splendour, for he is a master of experiment.

He knows from experience the natural sciences, in medicine and alchemy, in heavenly and terrestrial things. He knows all about the smelting of metals, working with gold and silver, and other metals, and all minerals... He is an expert in weapons and military matters, and has examined all aspects of agriculture and the measuring of fields... He follows knowledge for its own sake, and does not value honours and riches, even though he could make himself very rich with his knowledge if he wanted to.

(Opus maius, 1267)

Petrus Peregrinus, on 8 August 1269, while he was in Apulia with the troops of Charles of Anjou I besieging the city of Nocera, perhaps bored by the stalemate of The Electric Way

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operations, allowed himself a meditative pause, writing a letter to his childhood friend, a soldier named Sigier, who had remained in France in the village of Foucacourt. In the letter, he began to tell of the wonders of a magnetic stone, and how in it, strangely enough, opposites do not repel each other as enemies do in sieges, but by attracting each other, they unite to form a single thing.

His letter, full of many other curious observations, does not merely mention them as if they were a mere list of curious facts, but organises these observations by ordering them in succession, creating for the first time a theory, based also on small experiments created ad hoc to see their effects. He actually wrote the first treatise on magnetism, intended as a chapter of experimental science, paving the way for subsequent research.

His Epistle on the Magnet, far from remaining a private matter between two long-standing friends, met with great success and was widely circulated - at least by the standards of the time – such that Petrus Peregrinus could not have imagined. In fact, it was included in a sort of series of medieval school books, the Secretum Philosophorum, which spread in the learned circles of fourteenth-century England and landed on the continent in 1520, translated and reprinted into German by the publisher Gasser in Augsburg, then passed on further through other more or less accurate translations to about ten generations of students.

The Epistle of Petrus Peregrinus was also mentioned by an English scholar, a lover of experimentation and the search for the truth about natural phenomena: William Inexplicable attractions

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Gilbert, another giant in the history of magnetism and a key figure in the continuation of our account of the history of electricity.

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William Gilbert

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GILBERT’S ‘EFFLUVIUM ELECTRICUS’

Fluid as water

T

he word ‘electricity’ was attributed to the English scholar William Gilbert (Colchester, 24 May 1544 - London, 30 November 1603).

In his famous book ‘De Magnete’, printed in London in 1600, he introduced the word ‘electricity’ for the first time in history.

He did this by using the adjective ‘electricus’, which then passed from Latin into English ‘electric’, a word that evidently came to him by borrowing it directly from the Greek term élektron, the yellow amber, which was so popular in antiquity when it came to talking about this type of natural phenomena.

Although he wrote in Latin like most of the scholars of his time, he was inspired by ancient Greek to create the new term.

If he had chosen the Latin term succinum, which was used throughout the Middle Ages to describe yellow amber, instead of the Greek term élektron, we would today be talking about ‘succinine force’ or ‘succine potential’ instead of ‘electrical force’ and ‘electrical potential’. But respect for tradition and ancient authority clearly prevailed in choosing the root of the word, which has remained in universal use in all the languages of the world.

He was therefore, in a sense, the father who chose the first name for the natural energy that has become so important in contemporary society.

William Gilbert, who died at the age of 59 in London during the plague epidemic of 1603, was the classic giant on whose shoulders many other thinkers and scientists stood to advance their studies.

In turn, Gilbert had exploited the centuries-old observations

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of the classical tradition handed down by the amanuensis monks who, with infinite patience and dedication, copied the works of Aristotle and Pliny the Elder, and other important Greek philosophers, translating them into medieval Latin and saving them from oblivion for centuries.

In his treatise there was certainly also a certain influence of alchemical knowledge, which helped to tackle the problem of explaining magnetic phenomena from a new angle, one that was certainly unknown to Greek thinkers.

But the comparison of these two areas of knowledge led to a new way of understanding the phenomenon.

Gilbert’s ingenious idea was to build a small sphere of magnetite no bigger than an apricot that simulated, on a small scale, what was happening more macroscopically on Earth.

By moving a magnetised iron needle a few centimetres away from the magnetised sphere, he could observe the actual behaviour of a compass as it moved kilometres over the earth’s surface.

Gilbert called his ingenious technical device ‘Terrella’, i.e. ‘small earth’, a model that allowed him to postulate the existence of a magnetic field on earth.

Gilbert’s discovery of the earth’s magnetic field, which makes compasses point in a single direction, dispelled once and for all the erroneous belief that it was the pole star that attracted magnetic needles northwards by virtue of its mysterious natural virtue.

Fluid as water

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In his treatise De magnete, he was the first to describe other key concepts that would later be used by the scholars who were to follow.

Such as, for example, the idea that there are positive and negative polarities in the world, and the concept of electrical energy conceived as a fluid (effluvium) similar in behaviour to water, but absolutely invisible.

He also realised another fundamental fact.

The attraction of small objects that could be seen by rubbing an amber rod was different from the attraction of small iron objects to a magnet.

Gilbert was the first to understand that static electricity was something different from magnetism.

In Europe in the 17th century, studies on magnetism began to lay the conceptual foundations for the scientific study of electricity, a research that was initially low-key, but then progressed more and more rapidly in the 18th century, and then flourished with great strides in the 19th century in a series of unprecedented conceptual innovations.

Another fundamental step towards understanding what electrical effluvium was, with its powerful and amazing characteristics, was to be able to reproduce experiments with it in the laboratory.

But to do this it was necessary to be able to access it at will, artificially producing this invisible force so that it could be used in laboratories at the right time and in a controlled manner.

Thus, in the second half of the 17th century, the first rudimentary static electricity generators were created.

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3 Sparking machines

Francis Hauksbee

ROTATING AND ARCHAIC ELECTRO-GENERATORS

I

n the second half of the 17th century, the first device capable of producing large amounts of static electricity was developed by the German physicist Otto von Guericke (Magdeburg, 20 November 1602 - Hamburg, 21 May 1686).

Today, this brilliant Prussian scientist is remembered above all for his innovations on the concept of the vacuum, which brought him exceptional universal fame in his time.

In 1650 he invented the first pneumatic pump for creating a vacuum. The so-called ‘Magdeburg hemispheres’ experiment, with which not even the force of a team of four horses could detach a pair of cup-shaped hemispheres if a high vacuum was created inside them, is one of the most famous.

With the same passion and ingenuity he also devoted himself to the study of electrical phenomena that could produce effects even at a distance.

This was particularly close to von Guericke’s heart, because with his positive results in this then completely unknown field, he was able to validate a general thesis he had been working on for years: external forces could act in the vacuum.

In his Experimenta Nova of 1672, he described an ingenious device he built to create static electricity.

By filling a metal mould with sulphur powder and heating it over a fire, he could obtain a fairly large sulphur sphere of not too much weight to which a metal tube could be inserted on the vertical axis, so as to have a suitable support to create a rotation of the sphere.

If the tube was held and the globe rotated, the surface of

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the globe could be rubbed with a cloth continuously, powerfully charging the sulphur with static electricity in a very short time. The electrical charge thus obtained could generate spectacular effects at a distance.

When charged with static electricity, the sulphur sphere

19 Sparking machines

could attract small objects and then repel them by levitating them in the air, or even generate sparks that were visible even in a room that was not completely darkened.

Von Guericke also noticed that sometimes these objects, once attracted, were immediately repelled in the opposite direction, confirming in this respect the observations of the Italian Jesuit Niccolò Cabeo (Ferrara, 1586 - Genoa, 1650) who had described this strange phenomenon already in 1629.

Von Guericke’s ‘sulphurous globe’ also suggested to its inventor, somewhat as Gilbert did with his ‘Terrella’, to mentally conceive it as a scale model to explain certain anomalies in the motions of the planets, attributing an electrical cause of attraction and repulsion in a vacuum.

(Isaac Newton’s (1642-1726) law of universal gravitation was still to be formulated 15 years later).

Even though von Guericke’s sphere may make us smile at its extremely simple and almost disarming design in our time, to the extent that some are uncertain as to whether it can be described as an ‘electrical machine’ proper, the device had a very wide resonance.

In fact, it was the first electrostatic generator that was simple enough to make, providing scholars and enthusiasts of electrical phenomena with that strange electric “effluvium” capable of generating those spectacular remote phenomena: the attraction of small objects and luminous sparks.

Von Guericke’s generator was perfected in the following years by using other ‘electrifiable’ materials, such as glass, which, with the help of driving pulleys, could withstand The Electric Way

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longer rotations without wearing out or breaking into a thousand pieces in the hands of the experimenter.

One of the most famous of these very early electrical machines was the high-performance machine developed

by Francis Hauksbee (Colchester, 1660 - London, 1713), Isaac Newton’s brilliant laboratory assistant.

In the early 18th century, he was the first to use glass as an electrifiable material and to notice a new electrical phenomenon that no one had ever noticed before.

If mercury vapour was introduced into rotating glass beakers charged with static electricity, a strange and spectacular phenomenon was generated inside them.

When you put your hand near the ampoule and touched the surface, you could see a faint blue glow that magically followed the movement of your hand.

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At the time - this was 1703 - the luminescent properties of ionised gases, an electrical phenomenon that underpinned the operation of neon lamps and energysaving light bulbs before the advent of LED lighting, were unknown.

The effect was so curious that it was exploited by illusionists and charlatans for their fantastic performances with a creativity that still amazes today.

With Hauksbee’s electric generator, which was much more powerful than von Guericke’s sulphur sphere, one could create some very spectacular ‘electrifying’ situations.

For example, there were those who were able to set fire to a glass of cognac by simply placing a finger in the centre of the glass, or who surprised people with a display of ‘electrical beatification’, i.e. by making a luminescent aura appear around those who were willing to be the guinea pigs, very similar to the auras of the saints and holy people who had been depicted for centuries in sacred art with this distinctive attribute.

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Pieter van Musschenbroeck

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THE FIRST ELECTRIC CAPACITOR

A shocking jar

T

he ability to produce static electricity with rotating globes as early as the late 17th and early 18th centuries made it possible to produce a faint luminescence and sparks that were visible even in daylight.

It is natural that the use of these devices also spread to the drawing rooms to provoke wonder and amusement in the onlookers.

But the power of the machine, as you know, can sometimes play tricks on you, especially when you don’t know exactly what you’re doing, because - as is also written in the Bible: “Zeal without reflection is not good, and he who goes with hasty steps stumbles.”

(Book of Proverbs, 19:2)

It was with one of these enhanced rotating globes that an unusual incident occurred in 1746 in Leiden, a small town in southern Holland, which could have ended very tragically.

Pieter van Musschenbroeck (Leiden, 14 March 1692 Leiden, 19 September 1761), a Dutch physicist who was well known in his home country at the time, had built a small home laboratory to conduct experiments on the mysterious ‘effluvium’ that we now call static electricity.

Having obtained a von Guericke generator, he planned to electrify a jar half full of water to see the effects.

What would happen to the transparent water if you electrified it for a long time?

Was it possible to hold that mysterious fluid in the jar as if it were an invisible liquid?

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Could a submerged light spark be generated?

And would the electrified water in the jar glow faintly as it does in the luminescent abdomens of fireflies?

To answer these questions, Musschenbroek connected a thin iron chain to a current generator and made it so that half the length of the metal hung in the water of the transparent jar.

He was assisted in the experiment by a young helper, Alexander Cuneus, whose job it was to hold the jar and quickly take it to his master if he noticed any change in the water.

But nothing could be seen at all.

Although the minutes passed and the globe continued to charge, the water was still transparent.

Van Musschenbroek insisted on running the current generator at full speed for several minutes.

When he finally tired without being able to notice anything visible, he asked his helper to hand him the jar to check the effects.

It was then that Cuneus, holding the jar in his hand, inadvertently touched the iron chain with his other hand: the discharge - almost a million volts - hit van Musschenbroek’s poor assistant with extreme violence, leaving him stunned on the ground.

Without yet being able to understand all the dynamics set in motion by his electric jar, Pietr van Musschenbroek then tried to test the effect of that electric shock on his own skin. But the experience was so painful and traumatic that the researcher “would never try to get another shock again”, for any reason whatsoever, “not even if they gave him the Kingdom of France as a present!”

A shocking jar

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The water-based static electricity accumulator developed in 1746 by Musschenbroek, and independently also by Ewald Jurgen Georg van Kleist (Wicewo, 10 June 1700 - Koszalin, 10 December 1748), even a year earlier with an alcohol mixture, was named the ‘Leiden Jar’ in honour of the Dutch city where this ingenious invention originated.

This mysterious object capable of producing such powerful electrical discharges became very popular throughout the 18th century and was used both for scientific experiments and for entertainment in the well-to-do salons of the time.

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The Leiden jar was the first example of a very useful device that we now call a capacitor. Capacitors have now become a fundamental part of electronic components, and because of their ability to charge and discharge voltages they are used to filter out the ‘noise’ of many internal circuits in modern equipment, as well as to protect the circuits themselves from overload.

But how does a Leiden jar work? How is it possible to generate discharges that leave you stunned?

Science at the end of the eighteenth century was not yet able to answer these questions because the concept of an electric charge with which we easily explain the behaviour of this device today was not yet well known.

If, using a generator, we pass a current through the metal chain immersed in the water of a Leiden jar, we cause the positive pole charges to fill the inner conductor.

Since electric charges of opposite signs attract, while those of the same signs repel, the internal conductor will push away the charges of the same sign present in the external armature of the jar, which will progressively discharge to the ground, causing a difference of potential between inside and outside, which is more powerful the more we insist on “charging” the jar. If we then put the external armature in contact with the internal one, perhaps just by holding the jar in one hand and making contact with our feet on the ground, touching the chain with the other hand, the rapid passage of the flow of charges from one side to the other will re-establish the initial equilibrium, eliminating the difference in potential.

The charges discharged from the jar to the ground A shocking jar

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obviously very quickly generate a shock proportional to the amount of current we have put into the jar.

Although the danger is proportional to the potential difference and can be easily controlled, caution in handling a Leiden jar is therefore never too great and it is best not to overcharge it to avoid painful experiences!

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Stephen Gray

5

“CONDUCTING” MATERIALS AND “INSULATING” MATERIALS

Water pipes and protected islands

I

n 1729, the Englishman Stephen Gray (1667-1736) discovered a very important property of electrically charged materials.

Charge, or ‘electrical virtue’ as Gray preferred to call it, can be transferred by contact from one body to another. That is, a charged body placed in contact with an uncharged one transfers the properties of attraction or repulsion to it.

There must therefore have been a flow of particles (‘effluvia of electrics’) responsible for the movement.

And the sparks that emanated from the electrified object were caused – according to Gray – by a second stream that dispersed them into the surrounding environment.

By testing the transmission of these ‘effluvia’, Gray discovered that some materials could conduct this “electrical virtue” as easily as free flowing water in a pretty large pipe.

However, other materials offered some resistance to the flow, as if there was a dam holding back that electrical flow, or even stopping it altogether.

Gray mentally imagined this situation as a lake of water, and materials of this type as ‘islands’ separated from the water surrounding them.

He therefore called these materials “insulated”. Insulated, or in a term still used today, ‘INSULATING’.

While the materials that carried the flow of electric current were called “CONDUCTORS”, from the English “conductor”.

Stephen Gray had, for the first time in history, identified a fundamental property of matter found in nature, paving the way for new investigations into the understanding of electrical phenomena.

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One of his most famous and spectacular experiments was an one in which he brought the insulating or conductive properties of materials to the attention of his contemporaries. Using ropes made of silk – an insulating material – he hung wooden supports from a trellis and had a helper stand on them.

The man was then placed in contact with a static current generator that immersed him in the electric effluvium as if

he were on an island, thanks to the silk ropes that ‘isolated’ him from the ground without allowing the electric flow to disperse in other directions.

Water pipes and protected islands

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Thus electrified, the helper, completely protected from any discharge, was able with one hand to attract fragments of gold leaf to himself, just like an amber rod which had just been rubbed with an electrostatic cloth.

With a gesture that – to tell the truth – still arouses wonder today, and when you look at it, it retains an almost magical flavour.

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6

Vitreous or resinous?

That is the question

Charles Francois de Cisternay du Fay

THE FIRST SCIENTIFIC THEORY OF ELECTRICITY

T

he idea of the flow of electrical virtue that could be conducted by some materials more easily than others was taken up by the Frenchman Charles Francois de Cisternay du Fay (1698-1739).

Du Fay realised that it made little sense to talk about ‘electrical substances’ and ‘non-electrical substances’, according to the classification initiated by Gilbert and then taken up by many other scholars.

Rather, the attraction and repulsion properties of the same substances or materials in certain contexts had to be investigated.

Studying these phenomena, he began to work on isolated surfaces.

He noticed that very thin sheets of metal can repel each other when charged with static electricity.

He also realised that the opposite effect could be achieved, i.e. the same foils made of the same material could also attract rather than repel each other.

If a thin foil was charged by rubbing a glass sphere with a silk cloth, then placed next to a foil charged with a piece of amber rubbed with a woollen cloth, the two foils tended to attract rather than repel each other.

So, the material from which the foils were made had nothing to do with the phenomenon of attraction or repulsion, but was rather due to the type of electrical fluid that soaked them. Du Fay proposed to explain his observations in this way: In nature there must be two types of electrical fluid, a vitreous one from glass rubbed with silk and a resinous one from amber rubbed with wool.

The two fluids clearly have opposite properties and if The Electric Way

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they come into contact with each other they will tend to neutralise each other.

For the first time, a scientific explanation of electricity was proposed.

Although this theory of vitreous and resinous flows may seem absolutely outdated, and is now relegated to being a pure historical curiosity, it was of considerable importance for subsequent studies.

It was the basis for further investigation and discovery.

It could be tested in purpose-designed laboratory experiments to try to prove or disprove it and, for almost a century, it ignited the scientific debate on the nature of electricity.

It would be the American Benjamin Franklin who would demolish its foundations, proposing his alternative theory Vitreous or resinous? That is the question

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of a ‘single electric flow’, not divided into two types as proposed by the French school of Du Fay, but caused by the movement of tiny, invisible ‘positive charges’ and ‘negative charges’. But more about this in the following chapter.

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Benjamin Franklin

7 BENJAMIN FRANKLIN AND THE KITE IN THE STORM

Lightning in Philadelphia

O

ne of the founding fathers of the United States of America, Benjamin Franklin (Boston, 17 January 1706 - Philadelphia, 17 April 1790), made a fundamental contribution to the advancement of research into the nature of electricity.

Franklin, fascinated by the innovations coming out of Europe, began to work with electricity at an early age, having witnessed performances of electrical machines in 1749.

He shared, with other scholars of the phenomenon, a view of electricity as an invisible flow of force, a kind of fluid that under certain conditions quickly percolates through bodies.

But he was not at all convinced by the theory of the Frenchman Charles Francois de Cisternay du Fay that electricity was the manifestation of the collision of two distinct flows, the so-called vitreous and resinous electricity.

Experimenting with a group of friends on the wonders produced by a Leiden jar, he realised that it was not the water that contained the electrical charge, because by emptying the water jar, carefully without igniting the discharge spark, the same effect could be achieved.

It was therefore the glass of the jar which, after having been charged with electricity, rebalanced when the spark was released.

Using an electroscope, a pair of thin metal plates capable of attracting or repelling each other, and insulating a Leiden jar by placing it on an insulating material and then alternately grounding the electrode immersed in the water and the outer conductor, the electrical flow reversed, first The Electric Way

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charging the electrode ‘positively’ and then the outer conductor.

According to Franklin, the electrical flux was not of two kinds, because if a body had been charged above its ‘normal level’ it was positive, and if it was below that level it was negative. The flow was rebalanced from positive to negative, generating the discharge.

This type of reasoning, combined with careful observation of the Leiden jar, was extended by Franklin to the natural phenomenon of atmospheric lightnings.

They too – having many properties in common with the ‘fire stream’ noted in the jar (light, colour, twisting direction, rapid movement, explosive noise) – were essentially natural electrical phenomena.

Franklin’s intuition was to consider the electrical sparks in the Leiden jar as small miniature lightning bolts, similar to the large discharges that occur in nature during a thunderstorm.

If the discharge from the Leiden jar could then be discharged to earth by closing the circuit, then lightning could also be directed to discharge to earth, to a specific point which would disperse the energy to earth.

The lightning rod was about to be born.

But in order to convince the scientific world that lightning was nothing more than a very powerful electricity of natural origin, an apparatus capable of proving it had to be built.

In 1749 Franklin devised a perfect experiment to demonstrate this: on a high tower a sharp iron rod twenty Lightning in Philadelphia

39

or thirty feet long was to be firmly planted on the ground and would discharge the lightning to the ground.

If a man, isolated from a wooden platform, waited for a thunderstorm to pass through a hut at the base of the pole, he would be able to observe, without being electrocuted, the natural flow of electricity from the pole in the form of electric sparks similar to miniature lightning.

Unfortunately, Franklin could not find a building in Philadelphia tall enough to try the experiment.

Only three years later, in Europe, the French physicist Thomas Francois Dalibard (Crannes, 1703 - Paris, 1779), using funding from the King of France, managed to build a suitable apparatus in the small town of Marlyla-Ville, 25 km north of Paris.

On 10 May 1752, during a violent thunderstorm in the area, the 15-metre iron rod, which had been set up according to Franklin’s instructions, attracted the electrical energy in the air, discharged onto an earthed copper wire and generated the typical crackling and sparkling that is characteristic of very high voltage.

It was by pure chance that Dalibard’s assistant who witnessed the phenomenon was not electrocuted, but on that day, for the first time in history, it was realised that it was possible to extract static electricity from a cloud, and the lightning rod was born.

In America meanwhile, Benjamin Franklin, in order to test his electrical theory independently of Dalibard in Europe, devised the famous kite experiment.

Franklin decided to reveal the presence of natural electricity within a storm cloud by dispensing with the metal rod fixed The Electric Way

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to the ground and to bring a conducting wire directly into it, using a kite to be flown during a severe thunderstorm.

He hoped that the light hemp twine holding the kite by virtue of the rainwater impregnating it would become weakly conductive and replace the iron rod safely.

Franklin, in order to avoid being directly hit by the lightning strike, would also have protected himself with good insulation by wrapping his hand holding the kite string with a dry silk cloth.

In order to see the current flowing, Franklin thought of tying a brass key to the string of the kite at a short distance from the isolated hand. The force of the flow of electrical charges from the cloud would be concentrated on it, just as it was on the metal chain hanging in the Leiden jars.

It would have been enough to bring the knuckles of the other hand close to the brass key to set off a bright spark as the current passed through.

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The kite experiment took place, according to Franklin himself in Philadelphia on the morning of 10 June 1752, and was a complete success.

For the sake of the record, there are those who now doubt that such a critical and dangerous experiment ever took place, as we read in Tom Tucker’s 2003 book “Bolt Of Fate”, which proves with evidence from field simulations that Franklin’s kite never managed to hover in the air, but since his theory was essentially correct this is of little importance for the subsequent evolution of the history of electricity).

Benjamin Franklin coined several words to describe his experiments on electricity. In his Experiments and Observations on Electricity, we can read some of the words that have become commonly used: conductor, charge, discharge, armature, electrify.

He clearly demonstrated that electrical phenomena can be traced back to a single fluid with negative and positive polarity and not to two types of fluid, as previously thought.

He also showed that positive and negative charges, according to what is now known as the ‘principle of conservation’, always have equal quantities (i.e. if we rub an object with a cloth, it will be charged with positive charges just as the cloth will be charged with negative ones).

The widespread distribution of his popular pamphlets, not only in America but especially in Europe, gave a formidable boost to research into the behavior of lightning, even with unforeseen results as described in the following chapter.

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8

Electrocuted for science

Georg Wilhelm Richmann

BALL LIGHTNING THAT CHANGED THE HISTORY OF ELECTRICITY

T

he secret of lightning lies in the enormous difference in potential between “heaven” and “earth”, and as it had always attracted the attention of man, as a primordial force of nature, now as part of Franklin’s and Dalibar’s experiments into the field of electrical phenomena, it continued to attract the interest of researchers fascinated to somehow capture its power and energy charge. But, of course, the magnitude of lightning is always dangerous to handle.

In 1753, during a lightning storm, the German-Baltic professor Georg Wilhelm Richmann (Pernau, 1711 - St. Petersburg, 1753) wanted to repeat Franklin’s experiments in his laboratory in St. Petersburg.

Richmann’s intention was to retain atmospheric electricity in some Leiden jars connected in series so that their capacity could be measured.

Because of the enormous amount of electrical flux from the lightning strike, Richmann had arranged several dozen of them in his laboratory, but as he was preparing to connect them up, something happened that for him and everyone else that, up until then, had been completely unforeseen and unpredictable.

A bolt of lightning struck the antenna and formed a fireball that broke away from the metal pole and struck the researcher on the head.

The laboratory was flooded with blinding light and a roar, and the powerful electrical charge, which tore through the door frames before disappearing to the floor, having pierced Richmann from head to toe, leaving him lifeless on the floor.

That strange fireball was a rare ball lightning, a luminous The Electric Way

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plasma that can vary in size and form in very rare contexts before being reabsorbed into the ground. To this day, it is still not entirely clear how this happens and how such energy levels can persist in the environment for the duration of about ten seconds.

Some witnesses said that the poor man had a burn on his head and an exit wound on one of his shoes.

The discharge had passed through his entire body before discharging onto the ground.

A talented engraver from the St. Petersburg Academy of Sciences, a certain Sokorow, was present at the tragedy.

At Richmann’s invitation, he was supposed to illustrate the scientific experiment by means of his engraving tools, but he had to use his skills to preserve the chilling scene of the electrocution for posterity.

Sokorow’s image, more powerful than any speech, made a huge impression and shook not only the living rooms of half of Europe, but the entire world’s scientific community concerned with electricity. Was it ‘legitimate’ to want to capture lightning energy? Was there the knowledge and technical capacity to master this powerful phenomenon?

Or, for the time being, was it better to leave aside this type of absolutely unmanageable experimentation and instead pursue a safer course, that of research in laboratories to find a way of producing electricity artificially?

The latter direction was chosen and, as we shall see, it was an Italian, Alessandro Volta, who found the solution to this epoch-making challenge.

After the Richmann incident in 1753, all attempts to harness the powerful natural energy contained in lightning were abandoned.

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Only 150 years later, a young Serbian researcher, Nikola Tesla, proposed to exploit the potential difference between the Earth’s atmosphere and the ground in a controlled way, through his revolutionary inventions, but failed to convince the scientific community, who thought he was a crazy dreamer.

Today, we prefer to leave things as they are and to monitor the natural phenomenon remotely for the safety of people and property, through modern computer centres, but this will be discussed in the next chapter.

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9

“MAP” 5,000,000 LIGHTNING STRIKES PER DAY

Zeus’ works how to

T

he god of sky and thunder, in the religion of the ancient Greeks, was Zeus, leader of all the gods. His royal attribute, with which he is often depicted, is the thunderbolt.

In other cultures, we find that it is always a god who dominates the ‘fire from heaven’: Thor for the Germans, Teshup for the Hittites, Perun for the ancient Slavs.

Man fears its power and does not want to know how to control it.

Even today, after Benjamin Franklin’s famous kite which, so to speak, ‘pulled Zeus’ lightning down from Olympus and brought it into the order of electrical phenomena, the sudden appearance of such a powerful natural electrical discharge still generates a certain amount of fear.

Lightning with its 300 million volts per 100 m length can kill us if we are directly hit by it, but it can also produce serious problems if it is discharged into our electrical systems, causing damage to mains and digital equipment.

The modern computing power of computers makes it possible to quantify and follow, in real time, the course of thunderstorms and the amounts of energy they produce naturally.

It has been calculated, for example, that even on a clear day, there is a potential difference of 200,000 to 500,000 volts between the Earth’s surface and the ionosphere 80 km away.

This difference in potential is associated with an extremely low current density. Approximately 2 picoAmperes per square metre. (2 picoAmperes corresponds to 2 The Electric Way

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thousandths of a billionth of an Ampere). An absolutely negligible amount, but when multiplied by the total area of the earth’s surface (5.1 x 1,000,000,000 square kilometres) it reaches staggering figures. This difference in potential is maintained by storm activity. At any given moment there are about 2,000 thunderstorms simultaneously happening in different areas of our planet.

And in every second between 30 and 100 cloud-to-earth lightning strikes are discharged onto the ground, making an average of 5,000,000 lightning strikes per day.

Given the danger of lightning due to the risk of electrocution and also the damage that a sudden overload Zeus’ works how to

49

can cause to electricity distribution networks, lightning is therefore monitored continuously.

An international network provides real-time information on the situation worldwide.

The basis of this prodigious prevention system is a technological innovation, developed around the 1980s: lightning detectors capable of recording variations in the electromagnetic field in the monitored areas.

With the strategy of sensor triangulation, by means of computer calculations, electrical discharges of a certain intensity are recorded on a spatial map and all data are immediately made visible online.

This also creates probabilistic maps based on archival data, which are essential, for example, to guide the choice of the best sites for technological installations that could be damaged over time.

In Europe we have the EUCLID network (European Cooperation for Lighting Detection http://www.euclid. org/) with sensors in Switzerland, Germany, France, Benelux, Norway, Sweden, Finland, Spain, Portugal, England, Poland, Hungary, the Czech Republic, Slovakia, Austria, Slovenia and Italy.

Associated with EUCLID are a number of widely distributed monitoring organisations.

In Austria: ALDIS https://www.aldis.at/ active since 1991.

In Italy: CESI https://www.fulmini.it/ active since 1994.

In Slovenia: SCALAR http://www.scalar.si/sl/ active since 1998.

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10 Searching for the energy of life

Luigi Galvani

THE DISCOVERY OF BIOLOGICAL ELECTRICITY

R

ichmann’s tragic end, when he was killed in 1753 by a million-volt electric shock in his laboratory, led part of the scientific community to investigate death by electrocution.

Electricity, that mysterious ‘fluid’ whose physical origin was not yet known, could have devastating effects on the survival of living and recently dead organisms.

This theme, certainly a little ‘dark’ for our contemporary sensibility, had been brought into focus by some acute philosophical writings of Felice Fontana (Pomarolo, 15 April 1730 - Florence, 10 March 1805), court physicist at the Florence court of the Grand Duke of Tuscany, Peter Leopold of Lorraine.

Fontana, a toxicologist, had become well known at the time for his studies of anatomy and physiology and had inspired many schools of waxworks, including that of Florence, known throughout Europe for its macabre reproductions of dissected corpses.

In his ‘Ricerche filosofiche sopra la fisica animale’ (1755), the Trentino scholar had drawn the attention of the scientific community of the time to the fact that the bodies of people who died of electrocution putrefied more quickly than those who died of disease.

And that sudden decay of the body, which was viewed almost like a very complicated machine – according to Fontana – was to be attributed to the loss of the main property of muscles, namely their own capacity for movement.

This subtle, seemingly obvious speculative passage actually opened the way to an entirely new logical connection.

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Electricity, or rather that mysterious ‘electric fluid’ whose properties were beginning to appear on a scientific level, was also the cause of muscle movement, it was, so to speak, a ‘vital fluid’, a ‘motor’, ‘the engine of life’.

This is how physical and physiological research began to interact with each other.

The second half of the 18th century saw the birth of ‘electrophysiology’, a completely new field of investigation that was to yield absolutely astonishing results in a short space of time. The official start of studies in electrophysiology dates back to 1791.

In that year, the Bolognese physician Luigi Galvani (Bologna, 9 September 1737 - Bologna, 4 December 1798) published his booklet ‘De viribus electricitatis in motu muscolari’ (On the forces of electricity in muscular movement), the result of years of observation and laboratory research on dead animals.

Galvani used dead frogs for his experiments, partly for the convenience of finding organisms, from which the head had been removed and the crural nerves of the spine laid bare.

If you put a simple metal arc next to it, you could see a phenomenon that was completely unexpected, even disconcerting for Galvani’s contemporaries, because it had an almost magical flavour.

The contractions of the muscles excited by the ‘electrical fluid’ triggered by the metal conductor made the joints of the dissected frogs move with sudden jerks to the point that they seemed alive again.

Galvani was convinced that the movement of the legs of these amphibians indicated the existence of an ‘animal Searching for the energy of life

53

electrical fluid’, according to the widespread opinion in medical circles at the time that animals possessed a subtle fluid within their bodies that caused movement as it passed through nerves and muscles. Earlier speculations

by Isaac Newton (Woolsthorpeby-Colsterworth, 25 December 1642 - London, 20 March 1726) had already postulated, without scientific proof, an affinity or even link between the ‘electrical fluid’ of physicists and the ‘nervous fluid’ of physiologists.

Such an animal fluid acted even after the death of the organism, but was destined to dissipate in a short time. It was, in a sense, the ‘engine of life’.

Galvani thought he could explain the phenomenon by what he observed in the Leiden jar. Instead of the spark caused by the electrical discharge, there was a movement in the frogs. In fact, he was convinced that the muscles themselves were essentially a kind of Leiden jar and the nerves were the conductors of the discharge generated within it.

The ‘animal electricity’ could also have originated – according to another of Galvani’s hypotheses – in a specific organ of the body, the brain, which was positively charged, spreading the positive charge through the nerves, while everything else remained negatively charged.

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And so, by connecting a metal arc between the nerve and the muscle, as he had done when dissecting frogs, the potential balance was restored.

It was a theoretical hypothesis that in some ways closely resembled the old pre-scientific theory of humours, according to which animal bodies are traversed by internal forces in a delicate balance with each other.

But for the first time, Luigi Galvani’s experiments with frogs suddenly shifted the debate on those theories onto a strictly scientific field of evidence, through direct investigation using a rigorous and repeatable method of study in the laboratory.

It was Alessandro Volta who repeated these experiments from a different angle, arriving at very different conclusions, leading him to investigate an electricity unrelated to the biological one, which he called ‘artificial electricity’.

Like all discoveries in the field of electricity in those years, Galvani’s discovery was used to fuel highly questionable freak shows.

At the turn of the 19th century, public displays of improbable attempts to ‘resurrect’ dead organisms, such as small birds, cats, dogs abounded, and they were sacrificed purely for entertainment purposes.

The climax of these macabre shows came with experimentation on human corpses. Raising the bar was Galvani’s young nephew Giovanni Aldini (Bologna, 10 April 1762 - Milan, 17 January 1834). In the early years of the new century he organised sensational evenings in London in which bystanders seemed to see human bodies Searching for the energy of life

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come back to life with their heads removed and electrodes inserted into their spines as in Galvani’s dissected frogs.

It was a macabre aberration of scientific research that for the first time, as so many times since, would cross the line of ethics for a false higher reason.

Mary Shelley’s Frankenstein, or the Modern Prometheus (1818), a masterpiece of gothic literature that has now become part of the collective imagination, was to discover the aberrations of Galvanism.

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Alessandro Volta

11 THE VOLTA PILE, THE FIRST STATIC GENERATOR

The greatest discovery of all time

A

n anecdote has it that one day, the great scientist Albert Einstein was stopped by a young journalist in the street, who asked him whether his ‘Theory of Relativity’ was the greatest discovery of all time: “No, dear sir, the greatest discovery of all time was Volta’s battery!”

Einstein, who at the age of 20 had seen the wonders of the nascent technical industry when he visited his father’s factory in Milan, was clearly not choosing his answer lightly. It was in fact with this series of copper and zinc disks stacked one on top of the other to form a cylindrical column that Volta opened a new era for mankind. It was no longer necessary to study electricity by rubbing a piece of amber, waiting for the whim of lightning, or making do with a fleeting spark generated by a Leiden jar: the battery could produce electricity safely, and above all ‘continuously’.

By 1800, the year Volta published his discovery of the battery, science finally had a reliable tool with which to study electrical and electromagnetic phenomena.

Volta’s electric generator, which was extremely simple and easy to construct without requiring any special mechanical skills, had the advantage over all static electricity generators that the flow could be increased by putting devices in series.

In a way, Volta’s electric current resembled the flow of a steady, regular stream of water from a spring whose flow

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rate increased with the addition of other similar sources.

We will see in the following chapters how this characteristic was soon used for some exceptional technical discoveries that changed our world.

But how did the creative mind of the Italian scientist come up with such a device? Let’s see together.

Alessandro Volta (Como, 18 February 1745 - Como, 5 March 1827), a professor at the University of Pavia, was one of the first to take an interest in and enthusiastically welcome research into so-called ‘animal electricity’.

As early as 1793, however, just two years after the publication of De viribus electricitatis, he began to oppose the conclusions drawn by Luigi Galvani, which still had many weak points.

How was it possible to explain the vital movement of organisms through absolutely dead bodies?

The basic contradiction was also felt by Galvani himself, but unlike other unscrupulous scientists, he always abhorred the practice of testing his theories on animals that were still alive, as this would go against a natural order of Creation.

Alessandro Volta had also noticed another constant that deprived Galvani’s theory of universal validity: all of Galvani’s experiments were conducted on frog bodies in ‘humid environments’, and involved the presence of metallic arcs that evidently needed moisture to ‘excite the electric fluid from its resting state’.

According to Volta, the electrified muscles did not move by virtue of their own power, but were passively subjected to the discharge originating externally in the metal arc.

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Metal was therefore responsible for electricity.

Volta’s position completely overturned Galvani’s concept and became a new focus for future research.

Later, in the course of his experiments, Volta realised that the muscles of dead frogs could be stimulated to move not only by a metal arc, but also by contact with two plates made of different metals.

He became convinced that the electricity from the metal plates stimulated the nerve and the nerve stimulated the muscle, without the need for the muscle to be part of the circuit.

If this was true then the muscle was by no means to be considered like a small Leiden jar .The two metals alone were enough to generate what Volta called ‘an artificial electric flow’ to distinguish it from the ‘animal electric flow’ of galvanism.

An amusing anecdote has it that the idea of combining two metals was deduced by Volta, almost by chance during a banquet at a friend’s house.

If he tried to ‘taste’ the handles of a silver and an iron fork out of curiosity, he would have felt a sour, almost a faint tingling sensation.

And that strange feeling did not occur at all when tasting the cutlery with the wooden handles.

Was that a very weak electric shock?

Did your tongue – the ‘wet environment’ – react like Galvani’s frogs in contact with two different metals?

Volta’s highly original intuition led him to experiment with various pairs of different metals immersed in slightly acidified solutions.

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In 1793, with the help of the electrophorus (an instrument of his invention for measuring electrical intensity), he discovered that the ‘electromotive force’ of a bimetallic chain definitely depended on the two end links: if

61 The greatest discovery of all time

they were made of different metals, there was an electrical effect.

He developed a ‘crown of cups’ in which bimetallic strips of silver and zinc were immersed in an acid solution.

By alternating the cups according to pairs of Silver-Zinc strips so that the ends of the same cups were immersed in silver and alternately, zinc, it was possible to form a rather long chain in which the effect was amplified.

To replicate this intensity multiplier in a more easily transportable device that would not disperse the aqueous solution into the environment, Volta tried stacking discs of silver and zinc separated with paper towels soaked in the acid solution.

This produced a bimetallic column, literally a ‘stack’ of connected cells, without the need for the cups to be filled with sulphuric acid. By multiplying the cells in an ever-changing sequence, an amplified electrical flux was generated: the more coupled disks that were connected together, the stronger the intensity of the electrical flux that was generated.

But how powerful could this flow be?

In the illustrations of his invention Volta shows 4 cells of 4 pairs connected in series.

Each pair of discs could presumably generate around 0.8 volts, so 16 pairs of discs would almost certainly produce 12.8 volts – a ‘voltage’ similar to that of the electrical system in our modern cars in Europe!

By further increasing the stack of discs with 40 or 50 pairs, one could obtain a discharge powerful enough to The Electric Way

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achieve ‘arc’ sparks just like in the Leiden jar or like the shocks of a stingray: My apparatus or artificial electric organ,” Alessandro Volta remarked, “imitates the Leiden jar, and is even better than it because of the repeated ‘shocks’ it can give”.

Unlike Galvani, who died forgotten, Volta received honours and even a life annuity from Napoleon Bonaparte, who was very attentive to the modern scenarios that science and electrical technology had suddenly opened up.

At the First Electric Congress held in Paris in 1881 in honour of the brilliant Italian physicist and chemist who discovered the electric battery, it was decided that The greatest discovery of all time

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the unit for measuring electrical potential should be officially called the volt, something which is still universally accepted all over the world.

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12

Transferring material from one pole to the other

Luigi Brugnatelli

THE MAGIC OF ELECTROPLATING

T

he possibility of finally having a direct current generator at their disposal led many physicists to focus their attention on this new energy, which presented new phenomena in the laboratories, ones that had never before been observed in nature.

Scholars noticed that a strange phenomenon occurred in Volta’s battery after prolonged use. The negative pole electrode tended to be covered with a very thin layer of copper.

As the current continued to flow through the circuit for some time, the layer of metal grew even thicker, until it became the consistency of a foil a few fractions of a millimetre thick, and became easily detachable from the electrode.

On closer inspection, it could be seen that the metal foil deposited by electrical ‘galvanisation’ reproduced the surface of the negative pole in minute detail, as if it were a perfect plaster cast.

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This was a hint of the phenomenon we now call ‘electrolysis’, which would lead to the birth of a technique still used today in many manufacturing sectors, ‘electroplating’.

The chemist from Pavia, Luigi Brugnatelli (Pavia, 14 February 1761 - Pavia, 24 October 1818), a personal friend of Alessandro Volta and the discoverer of mercury fulminate, which is still used today as a powerful explosive, perfected this technique in 1805.

By means of electricity, a metal film could be deposited on objects immersed in a chemical bath (electrolyte) in which metal salts had been dissolved.

The part to be coated, acting as the cathode (negative electrode) of an electrolytic cell, could attract the positive ions contained in the electrolyte bath or partially from the metal of the anode (positive electrode).

In this way, perfect gold or silver plating could be obtained almost automatically, which was much more precise than when done by the heating process. This electroplating process also meant that the amount of precious metal could be kept to a minimum, with obvious economic advantages.

In 1837, the Russian physicist Moritz Hermann von Jacobi (Potsdam, 9 September 1801 - St Petersburg, 10 March 1874) tried to use this technique to obtain the relief of a metal plate worked with a burin.

Jacobi’s method subsequently led to significant improvements in the art of printing.

The so-called ‘galvanotyping’ made it possible to replace the common lead plates, which were easily worn out, with Transferring material from one pole to the other

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harder metal plates that could be used to print books and newspapers in much larger print runs, something which had previously been unthinkable.

Examples of this art can be found on display, for example, at the TMS Tehniški Muzej Slovenije (Technical Museum of Slovenia) in Borovnica.

In the late nineteenth and early twentieth centuries, electroplating was also widely used to create metal reproductions of natural organisms, a strange fashion that quickly spread throughout Europe.

Perfect copies down to the smallest detail of insects, crustaceans, molluscs and fish were exhibited in the wunderkammer (cabinet of curiousities) of wealthy collectors who wanted to amaze their visitors with sensational, vaguely exotic novelties that looked as mysterious as mummies or automata crystallised in forced immobility.

Often these collections, which rendered the organisms in 3D, perfectly, superior to any formalin preparation, were adopted in natural history museums as taxonomic preparations for the study of biodiversity.

The electroplating collection of the Museum of Natural History in Vienna, for example, is famous, with hundreds of extremely accurate pieces in perfect condition even 150 years after their creation. Equally fascinating to look at, although with fewer pieces, is the collection of the Museum of Natural History in Trieste created by the selftaught Andrea Rossovich (Trieste, 1840 - Trieste, 1896).

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13 Tell-tale bubbles

Anthony Carlisle William Nicholson

THE ELECTROLYTIC DECOMPOSITION OF MOLECULES

I

n 1800, using the direct current of Volta’s battery, the surgeon Anthony Carlisle (Stillington, 15 February 1768 - London, 2 November 1840) and William Nicholson (London, 13 December 1753 - Bloomsbury, 21 May 1815) discovered something that was then completely inexplicable.

By immersing two electrodes in water, gas bubbles were formed.

The higher the voltage of the battery, the stronger the “effervescence” effect found in the water through which the electric current flowed.

Those gases were different from each other: they were hydrogen and oxygen.

The two British researchers also noticed that the amount of oxygen coming out of the positively charged anode was exactly half the amount of hydrogen coming out of the negatively charged cathode. How come?

The solution to this dilemma was not immediately available at the time of the discovery, and would be found much later, through a ‘molecular’ model of matter that was then still unknown.

The smallest part of water, the ‘molecule’ below which there is no more water, consists of two elements: The Electric Way

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2 hydrogen atoms joined with 1 oxygen atom. These are simple elements, the basis of a wide variety of compound substances of which they are, so to speak, the building blocks.

The basic elements present in nature are not infinite, the list of most of them, as we know, is compiled some sixty years later by the Russian Mendeleev in his famous “Periodic Table of Elements”.

But, in the early 1800s, when gas bubbles were discovered emanating from the electrodes connected to Volta’s battery, the most obvious thing that emerged was a basic fact: The electric flux – for some strange reason – was capable of producing effects on matter, not only of attraction and repulsion, but could break matter down into simpler elements.

Thus electrolysis was born, which in Greek means: ‘to break with electricity’.

In the case of water, we are talking about ‘electrolytic dissociation’ of its constituent elements (oxygen and hydrogen).

It was also clear that the electrolytic technique, discovered almost by chance, was becoming a powerful means of investigating the constituent elements of other compounds as well.

Electricity suddenly became an ally of basic scientific research, but also of the chemical industry.

In 1813, for example, the English chemist Humphry Davy tried to repeat the experiments and connect a series of Volta batteries, obtaining a voltage sufficient to separate other chemical elements: chlorine, sodium and Tell-tale bubbles

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potassium.

Large-scale ‘electrolytic cells’ were used to obtain large quantities of chemical elements useful in industry and fertilisers for agriculture.

Michael Faraday (Southwark, September 1791 Hampton Court, August 1867), a close collaborator of Davy, but best known – as we shall see in Chapter 15 – for his discovery of electromagnetic induction, investigated the electrolytic phenomenon in depth and succeeded in discovering the characteristics that govern it.

Faraday’s two ‘Universal Laws’ of electrolysis state that: 1. the amount of substance discharged on the electrodes is proportional to the amount of electrical charge passing through the electrolytic cell 2. the same amount of electrical charge passing through different electrolytic cells discharges different amounts of ions, proportional to their respective atomic weights.

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Humphry Davy

14

DAVY’S ELECTRIC ARC

And there was light

I

n 1813, a truly spectacular experiment took place in the basement of the Royal Society in England: Humphry Davy (Penzance, 17 December 1778 - Geneva, 29 May 1829) tried to connect several hundred Volta batteries together in order to obtain a very powerful direct current.

With this mega-stack, the first of its kind in the world, Davy set out to generate a spark between two carbon electrodes to produce a kind of artificial lightning.

The ‘electric arc’ – as it was later called – between the two electrodes placed a short distance apart by Humphry Davy, had the characteristic of staying alive as long as there was electricity and its main effect was to emit a very violent, almost blinding light.

This was the birth of the arc lamp, the first ‘device’ capable of emitting continuous light generated by electricity.

For the first time in history, there was the possibility of having light available at the touch of a button instead of relying on burning illuminating gas or oil and paraffin candles.

After 1813, there was a rapid development of electric lighting, in lamps of this type, powered, of course, by Volta batteries, since an electrical distribution network had yet to be created.

Unfortunately, the arc lamp could not be used in places that were too small because its bluish-white light was too powerful and unsuitable for domestic environments where a few years earlier – especially in the homes of the wealthy – illuminating gas from coal distillation had begun to spread. Until the 1880s, when the first incandescent electric light bulbs appeared, Humphry Davy’s arc lamp was only used in very large rooms, such

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75 And there was light

as railway stations, main streets or public parks in large cities like London, New York, Paris or in factories. It was nevertheless an epoch-making revolution.

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15 The ‘spanner’ that unlocked the future

Michael Faraday

THE DISCOVERY OF ELECTROMAGNETIC INDUCTION

T

he English scientist Michael Faraday (Southwark, 22 September 1791 - Hampton Court, 25 August 1867), a pupil of Humphry Davy, had uncommon intuition and powers of observation. He devoted his life to the study of physics and chemistry with excellent discoveries and innovations. But when he turned his attention to the correlation between electrical and magnetic phenomena, he succeeded in discovering and correctly interpreting the phenomenon of electro-magnetic induction, the key that opened the world to the age of electricity.

The correlation between electricity and magnetism had already been noted in 1820 by the Dane Hans Christian Ørsted (Rudkøbing 14 August 1777 - Copenhagen 9 March 1851) by accidentally bringing a compass needle close to an electric wire, which deviated from its normal rotation towards North.

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Based on this simple observation, Faraday developed a series of devices in his laboratory to try to understand the intrinsic relationship between electricity and magnetism.

He discovered something completely new: if electricity causes magnetism, then magnetism also generates electricity.

So, it would be possible to generate electricity with a magnetic device.

Faraday then wrapped a simple paper tube with a thick coil of copper wire and passed a magnetic rod through the tube.

He attached an electrophorus (a charge meter) to the end of the loop and noticed that each time the magnet passed through the tube, in either direction, the device detected that there was a weak electric current inside the copper loop.

Electricity was produced! And this was due to the mechanical movement of a magnet inside a copper coil.

In 1831 Faraday attempted to optimise that result by transferring rectilinear motion onto a rotating copper disc that was passed through magnetic parallelepipeds.

Again, the result was astonishing: it was possible to produce continuous electricity simply by making a conductor move continuously in a magnetic field.

Faraday had discovered and harnessed the phenomenon of magnetic induction.

He later succeeded in formulating a principle to explain the phenomenon: “If a conductor moves in a magnetic field not parallel to it, an induced electromotive force is generated.”

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On the basis of this principle, which elegantly linked electricity and magnetism, it was possible to produce electricity, but also to achieve the opposite effect.

If electricity is fed into the copper coil that surrounds the magnet instead of drawing electricity from outside, then it is the magnet that will move.

By means of the electricity produced, for example, by a battery, motion can be generated. With another famous apparatus Faraday succeeded in visually demonstrating this principle. He hung a magnetic sphere from a wire and placed it perpendicularly on a mercury basin to which electrical energy was applied: the result was that the ball began to spin, as expected, around the magnetic field.

Like Volta’s battery thirty years earlier, Faraday’s discovery was epoch-making: like a spanner, it unlocked the technological future of mankind, steering it towards today’s modern world.

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Ernst Werner von Siemens

16 DYNAMIC AND ELECTRIC TRAMWAYS

Effective energy rotation

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t was not long before an effective electro-mechanical device producing electrical energy was developed: it was called a ‘dynamo’ (from the Greek dynamis = force).

Michael Faraday, a few days after experimenting with the effects of current on a magnetic rod running in a copper coil, tried to make the movement between magnet and coil continuous by reversing the dynamics of his experimental apparatus.

He came up with the idea of no longer alternately sliding a magnet inside a conductor, but rather of continuously rotating a copper disc inside two magnetic plates.

When the crank was turned, what Faraday had predicted happened: a flow of direct current was produced.

However, the output of a laboratory device such as the Faraday disk was very low and the disk tended to overheat due to the opposing induced currents.

In order to exploit the full potential of his discovery, it was essential to find a more efficient system that reproduced the electrical effect on a larger scale without losing energy in the form of heat.

This was a very important technical ‘challenge’ that would engage many other experimenters in the following years.

Among the first to build a dynamo according to Faraday’s principles was the Frenchman Hippolyte Pixii (Paris, 1808 - 1835).

In 1832, he created a vertical dynamo using a permanent magnet spun by a crank in copper coils. To overcome the problem of his dynamo, which reversed the current flow with each revolution, Pixii introduced an interesting new element: the so-called “commutator”, a split metal cylinder on the shaft, with two elastic metal contacts

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pressing against it. But even this system (which we will refer to as a rotating bipolar axial coil) was still weak; the current continued to surge. The series of “peaks” or pulses of current, separated by moments of “vacuum”, resulted in a low average power (and, as we shall see, this will be one of the main problems of the electric motor).

The solution came to an Italian scientist in 1859: Antonio Pacinotti (Pisa, 17 June 1841 - Pisa, 25 March 1912).

He replaced the rotating bipolar axial coil with a ring of soft iron onto which 16 coils were attached in series.

The continuous winding of this ‘multi-polar toroid’ was connected to the commutator at many equally-spaced points and the commutator divided into many segments.

This meant that part of the coil passed continuously over the magnets. The ends of the coils were connected two by two to one of the metal segments of the central magnetic cylinder, on which diametrically opposed “brushes” made contact, collecting the electrical energy produced by the movement of the ring around the magnet. By alternating the polarities induced in the 16 windings in rapid sequence at each turn, a fairly stable direct current flow was obtained.

Pacinotti’s system also had another important property: it was reversible. Instead of manually spinning the ring and collecting electricity from the brushes, Pacinotti tried connecting a Volta battery to it in 1869. The effect was that his ‘ring’ rotated without the need for the mechanical action of a crank. This was the basis for the later development of the DC electric motor. Unfortunately, Pacinotti was not quick enough to patent his device and his ingenious idea was later exploited by others.

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Another important innovation in dynamos that increased their power and finally brought them into industrial use was to equip them with self-powered electro-magnets.

The idea came independently of each other to the Englishman Henry Wilde in 1866 and to Ernst Werner von Siemens (Lenthe, 13 December 1816 - Berlin, 6 December 1892), the enlightened German industrialist who combined experimentation with exceptional industrial skills. In September 1866, Werner Siemens had a double-T assembly of a generator connected in series with an electromagnet in his workshop so that he could explore the effects of self-induction. When the double-T armature was manually operated, the Earth’s slight magnetism was sufficient to generate a weak selfinduction electricity which grew stronger and stronger after a few more rotations. Compared with dynamos using permanent magnets, Siemens dynamos could do without so much material, reducing the weight of the drive unit by 85%. Once the unnecessary weight was removed, the drive power required to make them move also fell dramatically, to 35%. The price of the new dynamo without the permanent magnets could be reduced by as much as 75% for the same power. This was a major step forward, especially in economic terms, which allowed electricity to be generated in Europe cheaply and used at much higher capacities.

We also owe another revolutionary innovation to Werner von Siemens: the first electrification of public transport.

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and built by Siemens in Germany, in what is now Berlin’s ‘Lichterfelde’ district, went into service on 16 May 1881, two years before an American version made by Van Depoele, a Belgian, was installed at the Chicago Exhibition (1883).

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The Siemens electric tramway in Berlin was 2.5 km long and could reach a speed of 20 km per hour. It was powered by a new generation ‘Siemens dynamo’ with self-powered magnets, and was driven by a steam engine housed in a small building near the departure station. The electric current line, in this first Siemens line – the first ever to be built in the world – ran on rails laid on the ground, but for greater safety, in later models Siemens and his collaborators opted for a connection via overhead cable.

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Letters on a copper wire

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Samuel Morse

THE ELECTRIC TELEGRAPH AND MORSE’S INTUITION

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he use of continuous electrical power enabled a great leap forward in communications. Indeed, throughout the first half of the 19th century, communication in Europe and America was still very slow.

There were no fast e-mail boxes, which nowadays are capable of making the rounds of servers all over the world in a very short time.

For example, if I want to send an ‘email’, I type in the text to be sent on my computer or smartphone screen and know that the message will take less than 3 seconds to arrive at its destination, for example, on a server located in America.

In the pre-digital era, people relied instead on the ‘letter’, handwritten on a sheet of paper. Between one town and another, the ‘missives’ were delivered to the sender, always by hand, by a postal service entrusted to couriers, sometimes equipped with horses to ensure fast delivery.

Most famous is the Pony Express service, which spread to America after the discovery of gold, or, to take a closer example, the mail service organised by the Thurn und Taxis family in the service of the Habsburgs, who had their horse changing stations spread over a vast territory between the present-day nations of Austria, Slovenia and Italy.

Horse-drawn carriages, trains and ships transported the letters to the various towns and from there to the surrounding suburbs.

Delivery of a communication, even an urgent one, took days, if not weeks, or even months if the address was overseas. The same problem of travel time weighed heavily on all information.

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Newspapers received the news to be published in the same way, with the same problems of delay in relation to the unfolding of the events to be brought to the attention of their readers. In order to overcome this major handicap, an efficient but still risky system was set up for urgent cases: carrier pigeons.

Birds with a formidable instinct to find their place of birth were able to deliver messages “by air”, over very long distances, even several hundred kilometres, fairly quickly.

Towards the end of the eighteenth century, people tried to send messages with optical ‘beacons’ that could be seen with a telescope.

In France, the inventor Claude Chappe (Brûlon, 25 December 1763 - Paris, 23 January 1805) developed an ingenious system of watchtowers equipped with flag ‘traffic lights’, which – weather permitting – could send encrypted messages via a secret code to escape prying eyes.

However, the great innovation came in the 19th century, when this technical art, which was called “telegraphy” (from the Greek “tele” = far and “graphein” = to write) because of its connection to handwritten letters, was perfected by means of electricity.

At the heart of the electric telegraph was a simple discovery: the electromagnet, which enabled iron objects to be attracted by electricity.

The first electromagnet was built in 1824 by British engineer William Sturgeon (Whittington, 22 May 1783 - Prestwich, 4 December 1850).

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the magnet attracted the nib soaked in ink, which left a trace on a paper ribbon.

But how could they write letters with such a system that could not reproduce alphabetical characters, but only issued simple continuous or broken lines?

To solve the problem of linking a sequence of these traces into a readable message, Samuel Morse (Charlestown, 27 April 1791 - New York, 2 April 1872), an American painter and son of a Protestant pastor, invented a code of lines and dots, the so-called ‘Morse Code’, which was still in use in telecommunications until a few years ago.

The first message in the history of telecommunications was sent from Baltimore to Washington on 24 May 1844 at 8.45 a.m., 4 words and an exclamation mark for a total of 18 characters: What /Hath /God /Wrought !

(What wonders God has created!) .--.... . - - / ..... - - ..../ --. --- -.. / .-- .-. --- ..- --. .... It was a biblical quotation from The Wisdom of Solomon which Morse, a fervent believer, had evidently chosen, thinking with gratitude of human creativity mirroring The Electric Way

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divine creativity which at that instant opened a new era.

Within a few years, the system invented by Morse spread like wildfire across America and Europe, forming a rich international network, obviously not comparable to today’s internet, but absolutely innovative because it was the first to see the light of day.

Soon, however, the Morse telegraph was faced with a major problem due to the use of direct current. The longer the wire on which the current flowed, the more resistance it encountered, and the strength of the electromagnet

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diminished proportionally, as it could not attract the nib with the force needed to write. The Morse signal was attenuated over long distances until it disappeared altogether.

This was overcome by fragmenting the network and then optimising signal reception with perforated tapes.

In 1908 the Morse Code signal ‘three dots, three dashes, three full stops or S.O.S. (Save Our Souls), became a standard in maritime radiotelegraphic distress code, and has entered common use today for all emergency situations.

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Thomas Alva Edison

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EDISON’S LIGHT BULB AND THE FRIULIAN INNOVATOR MALIGNANI

Electric light, in place of gas

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n the second half of the 19th century and in the first decade of the 20th century, gas lamps were still the most widespread means of lighting public streets in the world’s major cities. In Trieste, for example, although gas lighting was introduced in 1846, the Broletto Gasometer was built in 1901 to cope with the expansion of the city.

In Ljubljana gas powered public lighting was introduced in 1861. Gas lighting was much cheaper – about 75% less expensive – than wax candles or oil lamps, so it became common for villas and some domestic spaces to be equipped with this type of lighting, especially for the wealthier classes. From a statistical report of 1869, for example, we see that in Italy the cities that made the most use of gas lighting were Milan, Turin, Trieste and Naples and in all of them, except Naples, the use was mainly domestic, more than that of public lighting.

With the discovery of the very bright electric arc lamp in 1813, the lighting power far exceeded that of gas lamps.

But like all innovations, it also had its weaknesses: while its power solved the problem of large spaces – such as railway stations or public streets – it was ill-suited to small spaces, such as homes, which needed less light.

Another solution had to be found: electric light had to be “gentler”, less aggressive.

The right balance had to be struck between the power and the ‘colour’ of the light – a technical issue of no small importance, and one that would recur 150 years later with modern, energy-efficient lighting. Artificial light for indoor use should be neither too weak nor too strong, but also neither too warm nor too cold, as our visual system is naturally tuned to the spectrum of sunlight.

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The first solution to this problem came in 1878 with the incandescent bulb.

The operating principle is very simple: a filament made of a conducting or semiconducting material heats up to incandescence when a current flows through it, radiating light and heat. The reason for this behaviour of the filament is the “resistance” it causes in the current flow, which we can imagine as “friction” between electrons and molecules of the material of which the filament is made. However, while the heat serves to light the filament, it also creates other problems. Firstly, it represents an energy loss in the system. In incandescent lamps, most of the electrical energy is lost in the form of heat.

The heat, being caused by infrared rays, which are not visible to the human eye, is absolutely useless for lighting purposes. Secondly, overheating the filament at very high temperatures causes it to deteriorate very quickly because the material of which it is made burns or even “vaporises”, immediately interrupting the passage of electrical current.

Another problem for electric light, as mentioned above, is the “colour” of the light. Since artificial light is whiter the hotter the current going through the filament is, the main problem is to find a suitable filament that can heat up to a very high temperature to the point of emitting a “pleasantly white” light, without burning or melting. This is a very difficult balance to strike, given the complicated web of variables involved.

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both metallic and organic, enclosing the very thin wires in transparent glass bulbs, mainly to protect them from external damage, but also to prevent bursts and fires.

In 1878, the Englishman Joseph Wilson Swan (31 October 1828 - 27 May 1914) used carbon filaments made from burning paper, but the extreme fragility of the filament and the progressive blackening of the glass bulb within a few hours made his light bulb completely unusable.

In 1879, the American Thomas Alva Edison (Ohio, 11 February 1847 – Essex, 18 October 1931), with his pool of employees in the Menlo Park technology research laboratory in New Jersey, succeeded in improving the incandescent light bulb by using bamboo filaments protected by a vacuum glass bulb electrified with lowvoltage direct current (approx. 12 volts).

But despite advances in manufacturing, the life span of the very first Edison incandescent bulbs was still too short, estimated at no more than about 40 hours at best.

The rapid deterioration of the filaments led Edison to find a way of quickly replacing his light bulbs with a patented screw connection, the so-called ‘Edison connection’, recognisable by its elegant conical thread and wave profile, which has now become an international standard with the initials E (today in Italy we commonly use light bulbs with an E27 connection or the ‘mignon’ E14, while in the United States E26, E17 and E12 versions are used).

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production of Edison’s light bulbs.

Arturo Malignani (Udine, 4 March 1865 - Udine, 15 February 1939), devised an ingenious ‘chemicalphysical’ system to create a high vacuum in the bulbs of incandescent lights and also found a way to mass-produce glass bulbs in a way that was healthier for workers.

The Malignani system, still in use in modern lighting companies where a high vacuum is required, used arsenic, iodine and sulphuric acid vapours to combine with carbon filament vapours at the molecular level. The reaction of

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these components was far more effective than what could have been achieved with a simple air pump.

Edison Italiana acquired the Malignani patent and introduced it into the manufacture of all incandescent light bulbs on the international market.

Malignani’s work in the field of renewable energy sources is worth mentioning here for the influence it had in Italy, which is traditionally poor in coal and oil.

As early as the end of the 19th century, he planned to equip his city with hydroelectric power stations fed by the city’s irrigation ditches, which were, however, insufficient for the needs of mass consumption.

He therefore designed and built a more powerful hydroelectric power station that used the water from the Torre stream, harnessing it in a dam at Vedronza di Lusevera.

Thanks to Malignani’s initiative, Udine was one of the first cities in Europe to have a public and private lighting and a modern tram system powered by electricity from 1908 onwards, just as Siemens had done in Berlin a few years earlier (see chapter 16).

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Georges Claude

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NEON ADVERTISING SIGNS AND INDUCTION LAMPS

Other lighting ideas

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ith the widespread diffusion of the incandescent light bulb, for the first time in history, man freed himself from centuries of precarious lighting that had forced him to follow the natural day-night cycle in his daily activities, initiating the Second Industrial Revolution of the modern era.

The Achilles’ heel of Edison’s incandescent lamps was their very low efficiency, which led to the search for more economical solutions in terms of electricity consumption in the very early years of their introduction.

Among the most effective alternatives was the neon light, which used an electrical discharge fed by electrodes into a gas tube.

It was presented in Paris in 1909 by the French chemical engineer Georges Claude (Paris, 24 September 1870 23 May 1960), who was also responsible for other major innovations in the field of industrial gas processing. In 1897 Claude was the first to discover that acetylene gas could be transported safely by dissolving it in acetone, and independently of the German chemist Carl von Linde, he developed an industrial process to produce liquefied air (1902). During this research, Georges Claude discovered that the passage of electric current through glass tubes in which inert gases (such as neon) were present, produced light. And this light could be amplified considerably by fluorescent substances smeared on the inner surface of the tubes. The ions released by the passage of current in the gas in fact excite the molecules of the fluorescent substances, making them glow white or even a different colour depending on the mixture used in the coatings.

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Since there was no delicate incandescent filament inside them, Claude’s thin neon tubes could be hot moulded to create sinuous figures or even letters with a varied palette of light colours. This feature was immediately exploited by the advertising industry to create the spectacular low-energy neon signs that, until the advent of LEDs, illuminated cities all over the world, becoming the most visible symbol of the new industrialised and consumer society.

One of the projects that did not see the light of day due to obtuse marketing reasons arising from the so-called ‘war of the currents’ between Edison and Westinghouse was an completely new project that could have changed the development of lighting right from the start.

The idea embodied in a Nikola Tesla patent (‘System of electric lighting’ patent US454622, June 1891), was the magnetic induction light bulb, which was far more efficient in terms of both energy and lighting power.

Tesla exploited the physical principle that a rarefied gas emits light when excited by a magnetic field and developed an innovative lighting device.

Not requiring an electrical discharge as in arc lamps, not using consumable parts such as the carbon or tungsten filaments of incandescent bulbs, nor the electrodes of neon bulbs – Nikola Tesla’s magnetic induction bulb could operate with a constant output over extremely long periods of time and very low power consumption, anticipating modern induced light- emitting diodes (LEDs) by more than a century.

Magnetic induction lamps have been rediscovered by the modern-day electrical industry. Since 1990 they have Other lighting ideas

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started to be marketed for large industrial plants that need to illuminate large areas with low maintenance and consumption costs. Modern magnetic induction lamps can achieve an exceptionally long life of 100,000 operating hours – roughly 25 years of use – twice as long as LED lamps and even a hundred times longer than incandescent lamps.

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Nikola Tesla

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The ‘alternative’ of a genius TESLA’S ELECTRICITY THAT CHANGED THE WORLD

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s we saw in the previous chapter, Nikola Tesla patented a magnetic induction light bulb in 1891, which was much more modern than the solutions adopted up to then, but which only began to be produced industrially a hundred years later.

Other technological insights of Tesla’s were immediately successful and have become the common heritage of mankind. Two of these, in particular, had the merit of making a decisive impact on the stalemate of the late 19th century, bringing electricity into universal use in industry and homes. They are the ‘alternating current’ and the ‘three-phase electric motor’. In this chapter we look at the history of alternating current and why it was so important.

Tesla’s idea was to use a type of current that was substantially different from the normal current generated by chemical batteries or fixed-magnet dynamos.

The current flowing out of a Volta battery or a homopolar generator such as a Faraday disk is ‘direct current’ (DC) because the flow of electrons follows a single direction.

Like a stream of water that flows from one basin of greater height into another of lesser height, the DC current moves from the pole of greater potential (positive) towards the pole of lesser potential (negative). The flow of electrons moving from one pole to the other, just like water, can be used as energy to perform work. In a water mill, for example, the blades are moved by the flow of water, whereas in an electrical circuit, the work – switching on a household appliance, a light bulb, etc. – is done by the flow of electrical charges.

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The current invented by Tesla, on the other hand, behaves differently.

Using the dynamos he had invented, the Serbian scientist had found a way of making the polarity of the electrical

flow change very quickly at frequencies of tens of cycles per second, creating an ‘alternating current’ (AC).

Nikola Tesla, in his studies and experiments in the field of electromagnetism, induction and resonance, realised that this stratagem could have great advantages.

First of all, with alternating current the resistance of the conductor is lower than with direct current.

The basis of this phenomenon is Ohm’s law, which states that “The intensity of an electric current is directly proportional to the electromotive force and inversely proportional to the resistance of the conductor ( E = RI )”.

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The electrons within a circuit, changing direction many times in a very short space of time, do not travel along its full length, but only in a very short section within the molecular lattice of the conductor, finding much less resistance than if they were to cross it along the full length of the electric wire.

This is not easy to understand, but we can help by using our “hydraulic” comparison. In alternating current, it is as if a flow of water were continuously diverted from right to left and from left to right inside a pipe into which filters have been introduced to slow down the flow. If we were to intercept the flow of water (for example by introducing a motor) at an intermediate point in the pipe, the power of the jet would be greater than at the end of the pipe because in the latter case the “resistance” to the passage of the flow would be the result of the sum of all the impediments encountered along the way and not just some of them.

As alternating current found less resistance in the circuit, it could carry greater amounts of energy over considerable distances. All that was needed was to increase the voltage.

To understand this logical step, it is necessary to list the basic characteristics of an electric current: 1. VOLTAGE (measured in volts): this is the electromotive force, i.e. the thrust that the electrons receive from the current generator.

2. INTENSITY (measured in amperes): is the speed and quantity of electrons flowing in a circuit.

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3. RESISTANCE (measured in Ohm): is the opposition to the passage of electrons in a conductor.

4. POWER (measured in Watts) and is the product of Voltage and Intensity.

If a transmission line has to carry a power P, increasing the voltage (V) will lower the resistance (I). On the other hand, the power dissipated in the transmission line, according to Joule’s law, is given by R (resistance of the line) multiplied by the square of I. So, a higher voltage V necessarily corresponds to lower losses.

The alternating current system solved the distribution problem once and for all. It freed us from the need to have a large number of power stations at short distances from each other and from places of consumption (industry, private homes, public lighting). Alternating current power stations could be built in places far removed from population centres and the current could easily travel for many kilometres at voltages of thousands of volts and then be converted to reduced voltages of 110 volts or 220 volts for domestic use.

It must be said, however, that this system devised by Tesla initially met with stiff opposition from Thomas Edison, who had chosen to use direct current for years and in converting to “alternating” current would have to rebuild his industrial fortunes from the bottom up.

After years of disputes, some of them fierce, and some rather dirty tricks from Edison, in what was known in America at the beginning of the 20th century as the ‘War The ‘alternative’ of a genius

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of the Currents’, in the end the system that succeeded in imposing itself and convincing investors to risk their capital was Tesla’s, through the enlightened support of the American industrialist George Westinghouse (New York, 6 October 1846 - 12 March 1914).

As we know today, all our homes are supplied with alternating current. In modern systems connected to the alternating current grid, the frequency of the ‘vibration’ between the negative and positive poles can vary from country to country. In Italy and Slovenia, as in the rest of Europe, where alternating current generators run at 3000 rpm, the frequency is 50 hertz. In America, where this type of current was first used, the frequency is still the original 60 hertz of Tesla’s dynamos.

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21 “May the force be with..

Th(r)ee” Galileo Ferraris

THE ROTATING MAGNETIC FIELD AND THE BIRTH OF THE THREE-PHASE MOTOR

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he electric motor has undoubtedly been and still is at the forefront as the main device that has freed man from the drudgery of manual labour.

Its efficiency, in terms of consumption and return, is superior to any other type of engine invented over the centuries.

In the Middle Ages we had engines without fuel, for example the hydraulic mill, which used the kinetic energy of watercourses, or the windmill, which used the force resulting from the movement of air masses in the atmosphere.

As science progressed and discoveries were made in physics and chemistry, the foundations were laid for an engine technology that would free its operation from the vagaries of the seasons and the weather.

This gave rise to various solutions for fuel engines, some more or less efficient, some more or less complicated, using coal (steam engine), petrol (internal combustion engine) and diesel (diesel engine).

But the absolute prince of energy efficiency is still the electric induction motor, the most widely used in industrial applications.

At the heart of its operation is the physical principle discovered and theorised by Michael Faraday in 1831: electromagnetic induction, according to which movement can be produced by making an electric current interact with a magnetic field.

The next step was the discovery of the rotating magnetic field, i.e. the virtuous interaction of magnetic fields in order to produce a rotating movement of an object (rotor) when alternating current flows through it. The idea came The Electric Way

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from two brilliant researchers who, without knowing it, were working on the same theoretical problem: Nikola Tesla (Smiljan, 10 July 1856 - New York, 7 January 1943) in America and Galileo Ferraris (Livorno, 30 October 1847 - Turin, 7 February 1897) in Italy.

The latter discovered the rotating magnetic field in 1885, when he presented his electric motor running on two fixed orthogonal coils with alternating current at the Accademia delle Scienze in Turin in March 1888.

Nikola Tesla, on the other hand, came up with the idea of a rotating magnetic field with three components offset by 120°. This was the so-called three-phase electric induction motor, which produced a higher force by completely eliminating the dead points of motion in the rotor. As part of what has been called the ‘War of the Currents’ between Westinghouse and Edison, in order to impress the American public and promote alternating current over direct current, Tesla devised a device that, more than any mathematical demonstration, showed everyone the magic of the rotating magnetic field.

He created a technological version of the ‘egg of Columbus’, which was presented at the World’s Colombian Exposition in Chicago on the 400th anniversary of the discovery of America. Tesla’s “egg”, unlike the one with which Christopher Columbus won his voyage to the Americas, by denting the base to keep it upright “May the force be with.. Th(r)ee”

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in the dish, was an egg made entirely of copper and had no dents. It stood upright, spinning quickly like a top by virtue of the rotating three-phase magnetic field Tesla had created in a cavity beneath the dish.Between 1887 and 1888, Nikola Tesla filed various designs for increasingly sophisticated and high-performance induction motors with the US Patent Office. These patents led to the industrial production of electric motors for industry and traction, which are used today in modern electric cars.

85 years of discoveries and innovations for the threephase electric motor: 1800 – Alessandro Volta publishes his pamphlet on the battery he designed, capable of generating direct current.

1820 – Hans Christian Oersted observed the needle of a compass diverging from its position when approached by an electric wire and discovered that it is electric current that can produce magnetic fields.

1825 – William Strugeon invents the electromagnet (a coil with an iron core, when a current flows through it, acts like a magnet attracting iron objects).

1831 – Michael Faraday discovers the key factor from which the idea of an electric motor will develop: electromagnetic induction.

1856 – Werner Siemens invents a DC generator with a double armature. He is the first to adopt a coil winding in the slots, an idea that will mark a turning point in the design of electrical machines.

1885 – Galileo Ferraris builds the first induction motor 1887 – Nikola Tesla patents the first three-phase AC induction motor, which will be manufactured by George Westinghouse.

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Antonio Meucci Alexander Graham Bell

22

THE INVENTION OF THE TELEPHONE

The voice on the electrical wire

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he possibility of transforming electrical energy into sound waves was behind the invention of the telephone, the device for talking at a distance through an electric wire.

The forerunner of this exceptional application of electricity in the field of communications can be said to be the French engineer Charles Bourseul (Brussels, 28 April 1829 - Saint Céré, 23 November 1912) who in 1854, while employed in the French telegraph administration, built a first device that was not perfected, however, as it was met with general disbelief .

Another German engineer, employed in education, Johann Philipp Reis (Gelnhausen, 7 January 1834 - Friedrichsdorf, 14 January 1874) developed his own innovative invention in 1860, which he called the ‘Reis Telephone’. It consisted of a box with a circular hole on which a membrane could vibrate with a metal tip connected to a Volta battery. If the membrane was set in oscillation by the voice through a funnel, the vibrations were intercepted by the metal tip which transferred these mechanical impulses to an identical device placed at a certain distance to which an electromagnet was connected and which set in vibration a metal tip resting on the membrane. In this way, the sound vibration was transformed into an electrical signal and the electrical signal was transformed back into a sound signal at a distance. Reis’s device worked, but it was extremely weak and more of a laboratory curiosity than a telephone suitable for long-distance communication.

It took the inventiveness of an Italian experimenter, Antonio Meucci (Florence, 13 April 1808 - New York, 18 October 1889), employed as a technician in theatre The Electric Way

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productions, to develop a real telephone. While in Havana on business, working in the field of galvanoplasty and also mesmerism, he accidentally found the working principle of what he called the “talking telegraph”. In 1864, during an experimental session to help one of his friends with a severe headache, he placed a funnel in his mouth fitted with an electric foil which accidentally, when the electrical discharge occurred, transmitted the sound of the unfortunate man’s scream of pain to the other side of the wire where Meucci, with a similar funnel, had accidentally placed his ear. Applying himself to the discovery, Meucci devised a ‘telephone’, but was late in filing the drawings for the new invention, which caused him to lose the chance to patent it.

The first person to obtain a regular patent for the electric telephone in March 1876 was the naturalised BritishAmerican scientist Alexander Graham Bell (Edinburgh, 3 March 1847 - Beinn Bhreagh, 2 August 1922). At the time of his discovery of the possibility of transmitting voice by means of a device, he was the director of an institute for deaf and dumb people, and immediately used his invention to try to alleviate his patients’ hearing problems.

115 The voice on the electrical wire

The father of the telephone is still a controversial issue. It was contested by Meucci, who was granted recognition by the US Supreme Court in 1888.

Bell’s revolutionary device, like Morse’s telegraph, worked very well over short distances and somewhat less so over long distances where the problem of signal dissipation remained.

One of the most effective improvements to the electric telephone to make the voice less disturbed was the refinement of the microphone, which instead of metal foil used carbon plates that varied the electrical resistance as the pressure on the membrane changed. The idea came from Emile Berliner (Hannover, 20 May 1851 - Washington, 3 August 1929), the brilliant inventor of the gramophone and phonograph record, who in 1877 patented the first carbon microphone, which was then sold to the Bell Telephone Company for the staggering sum of $50,000.

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23 Waves for eliminating distances

Guglielmo Marconi

THE INVENTION OF RADIO

R

adio, the ability to communicate by transmitting and receiving communications instantaneously, without physical connections, is another epoch-making achievement for mankind.

The marvel gradually took place from 1864 onwards, when the Scottish mathematician James Clerk Maxwell (Edinburgh, 13 June 1831 - Cambridge, 5 November 1879) published his treatise on electricity and magnetism ‘A Dynamical Theory of the Electromagnetic Field’, in which he first proposed that the wave-like nature of light was the cause of electrical and magnetic phenomena and in which the existence of electromagnetic waves was confirmed.

Heinrich Rudolf Hertz (Hamburg, 22 February 1857 - Bonn, 1 January 1894) was the first to experimentally demonstrate the existence of the electromagnetic waves envisaged by Maxwell using an oscillator of his own design, the Hertzian dipole (1887), which was also capable of transmitting and receiving radio waves at a distance.

In his honour, frequency in the international system is measured in hertz (1 Herz corresponds to 1 oscillation per second).

An Italian, now practically unknown, Temistocle Calecchi Onesti (Lapedona, 14 December 1853 - Monterubbiano, 22 November 1922) invented the coherer, a device capable of detecting the presence of electromagnetic waves radiated at a distance in what was then known as the ‘ether’, the space separating one object from another.

Another Italian, Bolognese university professor Augusto Righi (27 August 1850 - 8 June 1920) had the idea of connecting Hertz’s oscillator to a Ruhmkorff coil,

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increasing its power. He experimentally demonstrated that electromagnetic waves exhibit the same phenomena (reflection, refraction and polarisation) as light waves, confirming that the two types of radiation are identical in nature. He was Guglielmo Marconi’s teacher.

In 1895, the Italian physicist Guglielmo Marconi (Bologna, 25 April 1874 - Rome, 20 July 1937) began his experiments on electromagnetic waves with the aim of finding a way to transmit and receive signals at a distance.

He had the idea to combine Temistocle Calecchi Onesti’s coherer with Hertz’s amplified oscillator by adding a transmitting and a receiving antenna.

On 8 December 1895, after several attempts, Marconi’s apparatus succeeded in communicating and receiving a wireless Morse signal for the first time in Italy (other experimenters had previously obtained similar results, such as Nikola Tesla, who had transmitted 50 km away at the beginning of the same year in a link at West Point, and the Russian Aleksandr Popov had built a receiver in May of the same year).

119 Waves for eliminating distances

Marconi perfected his radio, which initially operated on medium waves over a few tens of metres, with another key invention, the tuning device capable of selecting the receiving wave and distinguishing it from waves coming from other sources.

So, it was that on 12 December 1901, a century after the invention of Volta’s battery, Marconi succeeded in transmitting and receiving a radio wave across the Atlantic Ocean. On that day, the era of telecommunications was officially born.

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Oleg Vladimirovich Losev

24

THE DISCOVERY OF ELECTROLUMINESCENCE IN DIODES

A forgotten case

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n 1907 in the Marconi Laboratories in London of the Wireless Telegraph & Signal Company, the company founded by Guglielmo Marconi in 1897, a young assistant Henry Round (Kingswinford, 2 June 1881 - Bognor Regis, 17 August 1966) noticed something extraordinary.

While working on the improvement of galena radios, the so-called “cat whisker’s relevator”, he noticed that some aluminium silicate crystals (carborundum) used as diodes produced a weak light when an electric current passed through them. In Electrical World magazine N. 49 of 1907, Round described his discovery as follows: “I noticed a strange phenomenon.”, “When applying a potential of 10 volts between two points on a carborundum crystal, the crystal emitted a yellowish light.”, “Other crystals instead of yellowish light emitted a green, or orange, or blue light.”, “In all cases observed, the brightness was only seen in the negative pole, while in the positive pole there was a blue-green spark.”

He had discovered the phenomenon of electroluminescence whereby certain materials can emit light when an electron beam passes through them, but he could not explain it.

The one who understood the behaviour and potential of this pale light was, some 20 years later, a Russian researcher employed in Soviet radio manufacturing plants.

His name was Oleg Vladimirovich Losev (Tver, 10 May 1903 - St Petersburg, 22 January 1942). While observing the behaviour of diodes in an attempt to amplify the reception of radio signals, Losev noticed a The Electric Way

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strange luminescence coming from the negative pole of crystalline carborundum. Realising that this was a new type of light, he put a drop of benzene on the luminescent part of the diode and calculated the evaporation time. The drop evaporated in the same amount of time as the nonluminescent one. This was proof that the light was cold, i.e. that it did not produce any heat.

In addition, when a current flowed, the light from the carborundum crystal would be instantly activated and would be extinguished just as instantly when the current ceased. Losev immediately saw the great potential of this exceptional feature if it were applied to telecommunications: in 1927, he patented a ‘Light Relay’, an apparatus that could be used to transmit signals by opening and closing instantaneously.

Losev wrote about this: “My invention exploits the luminescence of a carborundum detector as a relay for fast telegraph, telephone, image transmission and other applications where a luminescent light contact point is used as a light source directly connected to a modulated current circuit.”

Losev’s intuition was fifty years ahead of the fibre-optic technology that is now widely used to speed up data exchange.

In numerous articles (unfortunately written only in Cyrillic, which certainly did not help the dissemination of his discoveries) the young Russian researcher tried A forgotten case

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to explain the effect of luminescence by defining it as “the inverse of the photoelectric effect”, but not having the mathematical basis of a quantum physicist, he never managed to demonstrate it. He didn’t even have the time.

Unfortunately, Losev died prematurely in 1945, aged just 38, during the siege of Leningrad, without being able to put his important discoveries to use. It was American researchers who, many years later, became involved in LED technology who noticed him.

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25

An innovation worth the Nobel prize

Akira Yoshino

RECHARGEABLE LITHIUM BATTERIES

A

kira Yoshino (Suita, 30 January 1948), a chemical engineer at the Japanese company Ashahi Kasei, began experimenting in the 1970s with alternative solutions for a chemical battery that were completely different from all previous ones. Based on the studies of Michael Stanley Whittingham (Nottingham, 22 December 1941) and John Bannister Goodenough (Jena, 25 July 1922), he found that lithium ions might be the best candidate for solving the main problem of rechargeable batteries: to be reversible, the discharging and charging process must not produce chemical changes to the battery components.

The normal battery technology used up to that time was based on a chemical process of oxidation-reduction between the electrodes which – precisely because of this chemical transformation – transferred electrons from the cathode to the anode in an irreversible manner so that the battery became weaker and weaker with each charging cycle. In the case of the lithium ion rechargeable batteries invented by Yoshino, there is no ‘chemical’ reaction between the elements making up the anode and cathode, but rather a ‘physical’ process of moving the lithium ions from one side to the other, so that the battery can be charged and discharged without there being any molecular change in the electrodes.

Using a simple image, we can imagine the two electrodes of a rechargeable battery as communicating vessels: two tubs of water connected to a tube at the bottom, which, depending on the relative height between them, empty and fill up due to the force of gravity attracting water from one vessel to the other. The flow of water (i.e. the current of electrons in the stack) passes from the highest to the

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lowest container draining the highest container and filling the lowest one, but fills again if the lowest container is moved higher up. In the case of communicating vessels, the stored energy that was used to overcome the force of gravity and move the lower container to a higher level is kinetic energy, whereas in the case of a rechargeable battery it is electrical energy that pushes the electrons back to their starting point.

When the charging voltage is applied, the lithium atoms in the positive electrode each lose an electron and are transformed into lithium ions, which migrate to the negative electrode where they regain their electrons.

At this point the battery is charged. When the battery is discharged, the reverse process occurs: the battery releases all the electrons from the negative pole and these, migrating towards the positive pole, generate the current, going to occupy the positive pole again.

When he began working on the problem of an efficient rechargeable battery, the Japanese physicist Yokino knew that the electrical charge inside the device would have to flow in a completely new way so as not to deteriorate the electrodes. He began using the lithium cobalt oxide ((Li1-xCoO2) identified a few years earlier by the naturalised German - American physicist John Bannister Goodenough (Jena, 25 July 1922), and tried to work out the best way to make it work as a positive electrode. When excited, this oxide actually delivered positive charges from lithium ions. But Yoshino did not yet have a negative electrode capable of absorbing and storing the lithium ions produced from lithium cobalt oxide. So he tried using a type of carbon with a modified crystal structure that An innovation worth the Nobel prize

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proved to be very suitable for the purpose. One last key ingredient was still missing: the right electrolyte to bridge the electrodes and transport the ions from one to the other.

All previous rechargeable batteries had essentially used water as the basis for electrolyte solutions, but this one had the big problem that it couldn’t carry more than 1.5 volts. So Yoshino had to reinvent an electrolyte that was much better than acidulated water, one that could carry more than 1.5 volts, which is unusable for the portable devices we use today. Yoshino decided to replace the water with an organic solvent (polyacetylene) and was able to almost triple the power, achieving 4 volts instead of the previous low voltage.

Another innovation introduced by Yoshino was to facilitate the exchange of electrons between the anode and cathode by increasing the surface area of the electrodes using aluminium foil coated with a lithium oxide/electrolyte mixture and then wrapped around itself, like a jam roll, to make cylindrical batteries.

However, the main problem to be solved before the new rechargeable batteries went into production was the natural instability of lithium. Being a very reactive metal, it overheated with each charge and discharge cycle and could in some cases catch fire or even explode. Yokino succeeded in solving this crucial problem by inserting a very thin film of a special plastic material with micro porosity to keep the various elements apart. If the battery overheated during the charging and discharging process, the film would melt after reaching a temperature limit, blocking its porosity to create an insulating barrier. With the interruption of the flow of lithium ions between the The Electric Way

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electrodes, the battery ceased to generate heat, immediately making the rechargeable battery safe.

The lithium-ion rechargeable battery was now ready to be produced and placed on the world market.

The Japanese company Sony was the first to do so in 1980.

In 2019, Akiro Yoshino was awarded the Nobel Prize in Chemistry along with the other two researchers who had made it possible to achieve this amazing result - Michael Stanley Whittingham and John Bannister Goodenough.

Thanks to the rechargeable lithium battery, it is now possible to carry a real-time connection with the whole world in your pocket, opening up unlimited possibilities for communication and information: an unprecedented resource for the contemporary world and a challenge for generations to come.

LITHIUM BATTERY: 180 YEARS OF DISCOVERIES AND INNOVATIONS 1800 – Alessandro Volta invents the first current generator with an aqueous electrolyte: the battery 1812 – Giuseppe Zamboni builds the first manganese dioxide dry cell 1816 – William Hyde Wollaston creates the cup stack 1836 – The Daniell cell is developed 1838 – The Grove Stack is built 1841 – The Bunsen burner is built 1859 – Gaston Planté builds the first accumulator (lead-acid battery) 1866 – Georges Leclanché invents and patents the progenitor of the dry cell An innovation worth the Nobel prize

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1886 – Carl Gassner patents a dry cell with a non-water-based electrolyte 1893 – The Weston battery is invented 1912 – Gilbert N. Lewis manufactures the first non-rechargeable lithium battery 1914 – Charles Féry invents the zinc-air battery 1936 – Emil Baur and H. Preis invent a methane fuel cell.

1942 – Samuel Ruben creates the mercury battery 1947 – O.K. Davtyan develops a fuel cell with a solid electrolyte 1950 – Samuel Ruben invents a silver oxide battery 1950 – Lewis Urry patented the alkaline battery 1954 – Francis Thomas Bacon developed a hydrogenoxygen fuel cell 1957 – Commercialisation of mercury batteries (RubenMallory) begins 1970 – The first non-rechargeable lithium batteries are produced by American and Japanese companies 1977 – Michael Stanley Whittingham, patented an experimental development of a lithium-ion rechargeable battery, not suitable for commercial use 1979 – John Bannister Goodenough finds process to increase energy density of lithium batteries 1979 – Akiro Yoshino finds a solution to optimise production and stabilise lithium batteries 1980 – First lithium batteries put into production by Sony 2019 – The Nobel Prize in Chemistry is awarded to the three inventors of the rechargeable lithium battery: Michael Stanley Whittingham, John Bannister Goodenough and Akiro Yoshino The Electric Way

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26 Crystals doped to create light

Nick Holonyak Jr.

LIGHT-EMITTING DIODES AND THE BLUE LED

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he term ‘LED’ is an acronym for Light Emitting Diode. In order to understand how it works, we must look at the concept of the diode, and then go on to see, in broad terms, how this electronic component, which is so useful in the field of telecommunications, could be used in a field so different from the one in which it was originally conceived.

A diode is a device which conducts the electric current in a single direction, like a non- return valve in a hydraulic pipe. A typical use of a diode is to ‘rectify’ alternating to direct current, for example in the power supply of smartphones, which transform the electricity supplied by the mains (220 volts alternating) to the appropriate voltage for the battery (5 volts direct).

A diode therefore has very low resistance – ideally tending towards zero – in one direction and very high resistance, ideally infinite, in the opposite direction.

With light emitting diodes, the passage of current in one direction between anode and cathode, the positive and negative electrodes, does not amplify a radio signal or rectify a current wave, but causes the emission of visible light.

Instead of the electrical energy being trapped in the circuit in the form of a flow of electrons, it is induced to dissipate externally in the form of photons (as predicted

by Einstein’s theory of the photoelectric effect, which in this case acts in a mirror-like manner).

The first LED was developed in 1962 in the laboratories The Electric Way

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of the General Electric Company by US researcher Nick Holonyak Jr. (Zeigler, 3 N ovem b er 1 9 2 8 ) . It produced a weak red light, suitable for indicator lamps.

It was a light-emitting diode made from a gallium arsenide crystal, artificially modified with a molecular technique called ‘doping’ to induce electrons to release photons.

In artificially ‘doped’ crystals there are two contiguous zones with an abundance of electrons at one end and a shortage of them at the other. The two zones are separated by a kind of electromagnetic barrier that acts like a membrane separating two solutions of a liquid of different concentration. When an electric current flows through the zone with an abundance of circulating electrons, the surplus electrons are pushed over the electromagnetic barrier as if by pressure, and go to rebalance the ‘poor’ zone. In the process, energy is consumed through the emission of photons, the LED light.

In general, the electromagnetic barrier can be overcome with a voltage of more than 0.7 volts - 0.9 volts, depending on the chemical element of which the LED is made.

The ‘doping’ of the semiconductor crystal is therefore of fundamental importance in order to achieve the wavelength differences and varying intensities of emitted light, and is the key process for achieving ever brighter LEDs. Crystals doped to create light

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After the General Electric Company’s pioneering work in 1962, more and more high- performance solutions were developed, switching from yellow to green light and testing new methods and semiconductor materials doped with increasingly sophisticated molecular ‘cocktails’.

A key step was the discovery in the 1990s of the cocktail ingredients for a blue light LED, which finally allowed the full triplet of the RGB (red green blue) palette to be available.

With these three colours, LED light can be produced in any shade of the visible spectrum, including, crucially for lighting purposes, white light. With the blue LED, it was possible to start the industrial production of LEDs for low- energy lighting and also the production of increasingly high-performance colour screens, from the smallest and lightest on smartphones to the largest in football stadiums.

The credit for the discovery of the blue LED goes to Japanese researchers Isamu Akasaki, Hiroshi Amano and Shuji Nakamura, who were awarded the Nobel Prize in Physics in 2014.

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Russel Shoemaker Ohl

27

SELENIUM CELLS AND SILICON SANDWICHES

All electricity in the light of the sun

T

he photovoltaic panel is obviously a static device, with no moving parts that dissipate energy in friction and has no need for a turbine driven by a combustion engine. This green technology has taken a long time to catch on, partly because from the discovery of the physical principle on which it is based to its large-scale commercialisation the process has not been short; it has taken roughly 125 years. Let’s take a look at how this happened.

At the basis of the operation of a solar panel is the physical behaviour of certain materials which, when exposed to light, generate a weak current flow.

In early 1888, the Italian physicist Augusto Righi (27 August 1850 - 8 June 1920), whom we have already discussed in connection with the properties of electromagnetic waves (see Chapter 23), discovered in his laboratory at the University of Bologna that if a conductive metal plate is hit by ultraviolet radiation, it becomes positively charged. Righi called this property the ‘photoelectric effect’, without being able to explain it.

A few years later, in 1839, the young French researcher Alexandre-Edmond Becquerel (Paris, 24 March 1820 - 11 May 1891), who was experimenting with the effect of electrolysis on different metals, noticed during some laboratory tests that if the basin with the electrolytic solution in which the metal electrodes were immersed was exposed to sunlight, a very weak electric current was generated, Since the effect was accentuated with some metals and diminished with others, he came to the essentially correct conclusion that it was the exposure The Electric Way

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of the metal to sunlight that generated the current and not the electrolyte solution. He called this phenomenon “photogalvanic” or “photovoltaic”, in honour of the two great Italian physicists. However, the fact remained as incomprehensible to him as it had been to Righi a few years earlier: why did light generate an electric current in a metal exposed to light?

Answering this question in the time of Righi and A.E. Becquerel was completely impossible. The theoretical key to the inexplicable behaviour would arrive more than sixty years later, in 1905, with Albert Einstein’s (Ulm, 14 March 1879 - Princeton, 18 April 1955) revolutionary theory of the photoelectric effect, with which the great German genius, who won the Nobel Prize for Physics in 1921 for this theory, introduced the concept of the photon, the ‘particle of light’. Einstein, who had been fascinated by the fantastic properties of electromagnetic fields since he was a boy, perhaps because his father had taken him with him to his Milanese dynamo and electric motor company when he was young, developed a completely original view of physics. Light, matter and even space are all interconnected, different expressions of relationships between energy fields (it is well known that the force of gravity itself, for Einstein, in the theoretical apparatus proposed in the ‘Theory of Relativity’ is not to be considered a real force, but a consequence of the curvature of space due to atomic interaction). This revolutionary theoretical approach dovetailed with German Max Planck’s concept of quantum physics published in 1900.

In order to explain how it was possible to generate All electricity in the light of the sun

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electricity from light, Einstein hypothesised the existence of particles of light with no mass and no polarity, which he called ‘photons’. Using mathematical calculations he was able to show that photons collide with the surface of metals and release negatively charged electrons, which move towards the positive pole and generate a flow of electricity.

So this was the theoretical framework, but the technique for exploiting the photoelectric effect would have to move along other lines, exploiting through direct observation of nature which materials could be the most efficient for exploiting the photoelectric effect for practical purposes.

It was soon realised that semiconductor materials can take on photoelectric characteristics better than metals (in materials science and technology, semiconductors are materials belonging to the category of semi-metals, which

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can take on a resistivity higher than that of conductors and lower than that of insulators; resistivity depends directly on temperature).

Selenium, for example, is one of these: it is the most powerful natural photoelectric material known. Its exceptional photoelectric property was discovered by chance in 1873 by Willoughby Smith (6 April 1828, in Great Yarmouth - Eastbourne, 17 July 1891), an English electrical engineer who was working on laying telegraph cables under the English Channel. He used selenium bars to test the goodness of portions of the cable that had to be checked before the whole cable was laid. The resistivity of the selenium could simulate the transmission as if the whole submarine cable had already been laid so that the defect could be eliminated before the work was completed, making it almost impossible to find the exact spot on which to intervene. But, contrary to expectations, the test was thwarted because the selenium rods became electrically conductive instead of resisting.

Smith noticed that the conductivity increased during the day and decreased at night. He then tried to shield the rods from sunlight: when he did this, the measurements were always successful. Selenium therefore reacted to light and produced electricity when exposed to the sun! Smith described the strange phenomenon in his article “Effects of Light on Selenium during the passage of an Electric Current” in the journal Nature on 20 February 1873, giving other researchers the opportunity to investigate in the laboratory the strange phenomenon he had first observed, which had caused him so many problems with All electricity in the light of the sun

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the testing of submarine cables.

The results were published in 1877 by William Grylls Addams and Richard Evans in their paper “The action of Light on Selenium”, published in the Proceedings of the Royal Society of London, and with the scientific endorsement of selenium’s exceptional properties given by such a prestigious scientific journal, the time was ripe for the development of a photovoltaic cell, which was soon realised.

The idea came from the American inventor Charles Fritts (1850 - 1903). In 1879, he used selenium to create the first photovoltaic panel, consisting of a layer of selenium and a layer of gold. He mounted one – very expensively – on the roof of a New York skyscraper in 1884, successfully proving that his “electrical generator with no moving parts” actually worked. The efficiency of that photoelectric panel, the first in the world, was about 1% compared to 29% for today’s best panels. Its Achilles’ heel, of course, was the cost of materials, which was too high compared to the very low efficiency. Fritts’ ingenious but very expensive invention was therefore nipped in the bud and soon forgotten.

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some ninety years later – photography. Small selenium and gold leaf panels are now commonly used in the sensors of digital photo and video cameras.

For the solar panel to become commonly used as a power generator, other less expensive materials had to be found. The search took many years, and finally silicon was identified as a semiconductor material that could have a good photovoltaic yield with a molecular “doping” treatment (similar to that described in the previous chapter for the LED).

It was Russell Shoemaker Ohl (30 January 1898 - 20 March 1987), the brilliant engineer employed by the famous Bell Labs of the American electronics industry, who in 1941 succeeded in developing a siliconbased photovoltaic cell without the need for gold leaf.

The basis for this breakthrough was the discovery, made three years earlier, of the operation of the electromagnetic barrier, the so-called P-N junction, in semiconductors ‘doped’ with impurities to increase their effect, a technique used in all types of diodes produced in the electronics industry. In the silicon photovoltaic panel, when sunlight comes into contact with the doped silicon, it produces electrons, which are not allowed to flow back All electricity in the light of the sun

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into the circuit and stabilise in the initial band of origin, but are ‘forced’ to flow, almost by osmosis through the membrane of the junction, in one direction only, thus creating the solar panel’s direct current flow.

In 1955, based on the work of R.S. Ohl, Gearl Pearson, Daryl Chaplin and Calun Fuller, also of Bell Labs in the US, perfected a silicon cell capable of powering a transceiver for the military, and in 1958 a photovoltaic cell was installed on the Vanguard satellite that powered the device, which was placed in Earth orbit for six years.

After 1963, when the Japanese company Sharp started its mass production of silicon solar panels, the photovoltaic industry took off incredibly all over the world.

America, Europe and China are now competing to make this technology more widespread at lower and more competitive prices in view of the green conversion undertaken by many countries to solve the problem of global warming and climate change.

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SUMMARY An irreplaceable resource 1. Inexplicable attractions

The discovery of electrical and magnetic phenomena

1 5

2. Fluid as water

13

3. Sparking machines

17

4. A shocking jar

23

5. Water pipes and protected islands

29

6. Vitreous or resinous? That is the question

33

7. Lightning in Philadelphia

37

8. Electrocuted for science

43

Gilbert’s ‘effluvium electricus’ Rotating and archaic electro-generators The first electric capacitor “Conducting” materials and “insulating” materials The first scientific theory of electricity

Benjamin Franklin and the kite in the storm Ball lightning that changed the history of electricity

9. Zeus’ works how to

47

10. Searching for the energy of life

51

11. The greatest discovery of all time

57

12. Transferring material from one pole to the other

65

13. Tell-tale bubbles

69

14. And there was light

73

15. The ‘spanner’ that unlocked the future

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“Map” 5,000,000 lightning strikes per day The discovery of biological electricity The Volta pile, the first static generator

The magic of electroplating

The electrolytic decomposition of molecules Davy’s electric arc

The discovery of electromagnetic induction

16. Effective energy rotation

81

17. Letters on a copper wire

87

18. Electric light, in place of gas

93

19. Other lighting ideas

99

Dynamic and electric tramways The electric telegraph and Morse’s intuition Edison’s light bulb and the Friulian innovator Malignani

Neon advertising signs and induction lamps

20. The ‘alternative’ of a genius

103

21. “May the force be with.. Th(r)ee”

109

22. The voice on the electrical wire

113

23. Waves for eliminating distances

117

24. A forgotten case

121

25. An innovation worth the Nobel prize

125

26. Crystals doped to create light

131

27. All electricity in the light of the sun

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Tesla’s electricity that changed the world The rotating magnetic field and the birth of the three-phase motor The invention of the telephone The invention of radio

The discovery of electroluminescence in diodes Rechargeable lithium batteries

Light-emitting diodes and the blue LED Selenium cells and silicon sandwiches

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The slowing of climate change and the preservation of energy resources are two global challenges that require concrete measures aimed at saving energy and improving energy efficiency to be taken. Italy and Slovenia are working to achieve the EU targets set for reducing greenhouse gas emissions and improving energy efficiency. The LightingSolutions project will contribute by implementing activities that will improve the energy efficiency and lighting management of public facilities, while at the same time ensuring more conscientious energy management and the adoption of energy-efficient behaviour.

GORIŠKA LOKALNA ENERGETSKA AGENCIJA

COMUNE DI DOBERDÒ OBČINA DOBERDOB

COMUNE DI MEDEA