HOW IT WORKS
SPACE STATIONS
Find out how these habitable platforms are assembled in orbit.
THE RIVER NILE
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ISSUE #44
A journey down one of Africa’s most important and beautiful waterways.
ELECTRICITY
GRAVITY ON JUPITER SLOT CANYONS
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ELECTRICITY STATIC • GENERATORS • SWITCHES • CURRENT • VOLTAGE
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FEATURES
ISSUE #44
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ELECTRICITY
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Illustration by Charles Miller
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Learn about the complex junction between the upper and lower body.
How legacy motorcycles are being brought back up to date and up to speed.
A journey down one of Africa’s most important beautiful waterways.
Take a tour around the majestic hub of the British Empire government.
PELVIS
MOTORBIKES
THE RIVER NILE
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50
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What technology can you find in a pair of typical flattening irons?
Find out how these habitable platforms are assembled in low Earth orbit.
Discover how nature creates these breathtaking natural structures.
HAIR STRAIGHTENERS
APRIL 2013
SPACE STATIONS
HOUSE OF PARLIAMENT
SLOT CANYONS
HOW IT WORKS
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CONTENTS
Meet the Team Find out more about the team of HOW IT WORKS…
ISSUE #44
SCIENCE 7 Electricity
Get the lowdown on everything you need to know about the fascinating world of electricity
TRANSPORT 42 Classic
Editor
If you think the Nile only flows through Egypt, think again. Follow its 4,130-mile course now from page 60.
46 Ejection Seats
22 Good Bacteria
48 London’s First
Cable Car
What makes the pelvis such a flexible part of the skeleton and why is this essential for childbirth?
48 Heroes of
Transport... The Wright Brothers
Why are Wilbur and Orville Wright history’s most famous aviators?
TECHNOLOGY
SPACE
26 Mega Pipes
How was the Nord Stream natural gas pipeline laid below the sea between Russia and Germany?
HELEN
Senior Art Editor
The majestic images of Antelope Canyon have inspired me to go check it out for myself.
54 Impact Craters
34 Image
57 Gravity on Jupiter
Stabilization
36 Atomic Force
Microscopes
BEN
39 Smart Glass
Pipies aren’t very interesting... unless they are really big: the challenges in creating the Nord Stream pipeline were insane.
40 Pearl River Tower
HOW IT WORKS
Discover how a 400-ton floating science laboratory can be built on the very boundary of space.
32 Gaming Joysticks
Straighteners
4
50 Space Stations
31 Binoculars
34 Hair
Features Editor
How legacy motorcycles are being brought back up to date and up to speed.
20 Tonsils
24 Pelvis
ROBERT
Motorcycles
Is this really the most self-sufficient, eco-friendly building on Earth? We study it to find out...
57 Stellar 58 The Asteroid Belt
Where did this rocky ring of cosmic debris hanging between Mars and Jupiter come from?
COVER
IIllustration for How it Works by Charles Miller
Thomas Edison Edison patented a system for electricity distribution in 1880, which was essential to capitalize on the invention of the electric lamp. On December 17, 1880, Edison founded the Edison Illuminating Company.
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HOW IT WORKS
SCIENCE COVER STORY
ELEC TRI CITY Discover what electricity really is and how centuries of science have managed to tame its powers.
CATEGORIES EXPLAINED ENERGY CHEMISTRY PHYSICS
APRIL 2013
HOW IT WORKS
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SCIENCE
ELEC TRI CITY Discover what electricity really is and how years of science have managed to tame its powers.
CATEGORIES EXPLAINED >>
ENERGY
CHEMSITRY
PHYSICS
F
ROM LIGHTNING bolts to electric circuits, electricity has many faces, but all are linked to the existence and movement of electrical charge. When it comes to powering the gadgets in our homes, the star of the show is the electron- a minuscule but significant particle found in every atom. An atom consists of negatively charged electrons that orbit a nucleus made up of positively charged protons and electrically neutral neutrons. Opposite charges attract and so electrons are held captive by the nucleus’s positive charge. Normally, there are equal numbers of electrons and protons, canceling out each other’s charges and leaving the atom with a neutral charge overall... until electricity comes along to shake things up, that is. Inside a metal, atoms rub elbows in a tight lattice, sharing one or two of their outermost electrons which meander in all directions. Under the right conditions, these free electrons can be persuaded to travel en masse in one direction. The resulting charge is what we call an electric current. Electric currents can also be carried by ions charged particles which occur, for example,when an atom loses or gains an electron. For instance, when salt dissolves in water, positively charged sodium ions and negatively charged chlorine ions are freed from the shackles of solid salt and roam freely. Materials that contain high densities of wandering electrons or ions are called conduc-
tors. Metallic conduc tors like copper are ubiquitous in electrical appliances, but ionic conductors get their share of the limelight inside batteries and even living creatures. Other materials, such as rubber or glass, are configured in such a way that their electrons cling tightly to atoms, making it difficult for a flow of electrons to occur; these are insulators. All electric currents are not created equal, with several different factors affecting the flow of electrons. When a battery is connected to a light bulb, the current that flows depends on the voltage or potential difference applied by the battery and the resistance of the light bulb. Imagine a pump forcing water through a pipe: the battery is the pump and the voltage is the ‘pressure difference’ across the pipe. Increase the voltage and the current increases too. The bulb’s resistance, expressed in ohms, is a measure of how difficult it is for the current to pass. Akin to forcing water through a partly blocked pipe, the greater the resistance, the smaller the end current: i.e. current (amps) is the voltage (volts) divided by the resistance (ohms).
High voltage
Static electricity commonly causes your body to build up voltages of 10,000-plus volts. Fortunately the current discharged is too weak to do any serious damage.
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WHAT IS ELECTRICITY?
The nature where itit comes comes from, nature of of electricity, electricity, where and how how ititmoves movesand andwhy whyit itis is powerful. soso powerful
NUCLEUS
Positively charged protons and neutrons (with no electrical charge) make up the atom’s core.
CHARGE
SHELL
One or more negatively charged electrons balance the nucleus’s positive charge, orbiting around the nucleus in layers
FREE ELECTRON
One or more negatively charged electrons balance the nucleus’s positive charge, orbiting around the nucleus in layers called shells.
ELECTRO MAGNATISM
DIRECTION
The direction of the magnetic field is determined by the direction of the current.
COIL
By wrapping a conductive wire into a tight coil (often around a metal core), the magnetic field is concentrated.
POWER SOURCE
A basic electromagnet consists of a conductive coil of wire connected to an energy source (a battery pack, for example).
CURRENT METAL ATOMS In side a metal, tightly packed atoms form a lattice but share their outer electrons.
ORGANIZED MOVEMENT
When a voltage is applied, the free electrons all rush in the same direction, creating a current.
APRIL 2013
FREE ELECTRONS
Thermal energy causes these free electrons to drift randomly in all directions.
HOW IT WORKS
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SCIENCE
HOW ELECTRICITY GETS TO YOUR HOME Power Station to Power Socket POWER STATION GENERATOR
The electricity generated inside the power station is alternating current with a voltage of around 25,000 breaking to prevent electric shocks.
STEP-UP TRANSFORMER
A transformer boosts the currents voltage up to about 400,000V for it to be transported.
PYLON
Lines are attached to pylons arms with insulting glass or ceramic to prevent charge seeping out into the environment.
SUBSTATION
A second series of transformers reduces the current’s voltage to the levels required for industrial applications around 35000V.
STEP DOWN TRANSFORMER
A final transformer reduces the voltage to 2,300V for use around the home.
E
LECTRICITY DISTRIBUTION is taken care of by a ‘grid’, a tromagnet. The current produced by a power station is alternating national network of transmission lines connecting pow(AC), meaning the flow of electrons periodically changes direction er stations to local substations and finally to the homes of (as opposed to a battery which provides a constant flow of elecconsumers. In the US alone, there are over 30O,OOO kilometers trons in one particular direction- ie direct current, or DC). The elec(186,OOO miles) of wiring dedicated to electricity distribution. tromagnet therefore produces a varying magnetic field, enabling it The UK has just one network- the National Grid- while there are to induce a voltage in the second coil. ¶The size of this second voltthree different networks in operation in the States. ¶The grid canage is determined by how the wire coils are set up. If the incomnot store electricity, so the output from power stations must miring wire has ten loops and the outgoing wire just five, the voltage ror people’s varying needs, from the moment you put the kettle will be doubled. The opposite arrangement is used to reduce volton in the morning until you switch off your bedside lamp at night. ages. ¶With its voltage increased dramatically, electricity is ready As a result, at peak periods electricity is often imported from powto hit the road on the electrical equivalent of a high-speed motorer stations far away, making efficient transmission a must. ¶Before way: high-voltage transmission lines. High-voltage lines stretch heading to your home, the electricity generated by a power staover huge distances, held well out of reach by towering electricition has its voltage boosted. When a wire transmits a large electric ty pylons. Before entering towns and cities, substations bring the current, resistance causes it to lose energy as heat. The bigger the voltage back down to safer levels. Cables then usually transport current, the more resistance is created and so the greater electricity underground for safety. ¶Further transformers the waste. The solution is to ramp up the voltage, meaning With voltage supply end users with different voltages, with relatively the same amount of energy can be transported by a much increased, high voltages provided for industrial purposes and lower weaker current. ¶Inside substations, there are clusters of electricity voltages reserved for domestic use. ¶Anyone who’s ever transformers which progressively step up the voltage cre- is ready hit taken a hair dryer across the Atlantic will know that counated by the power station’s generator. Once again, induc- the road on tries use different voltages as well as different plug shapes. tion plays a vital role. A simple transformer consists of a the electrical Largely for historical reasons, most countries worldwide dual electromagnet: a doughnut or horseshoe shaped iron equivalent of use 220, 230 or 240 volts, whereas North and Central core with two distinct coils of wire wound around it. The a motorway. American countries have almost all opted for 120 volts. first coil is connected to the generator, creating an elec-
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Power House
LIGHT SWITCH
OUTLET SOCKET
Connected to lights in the walls or ceiling, a single plat can have op to four switches (or gangs). Cords might be used in bathrooms to avoid wet hands coming into direct contact with the switch.
After its voyage from the power station, how is electricity distributed around a home?
FUSEBOX
This familiar square or rectangular fitting can feature one or several outlets for plugging portable items like lamps to power cables in the walls
Your home’s circuit breaker or fusebox keeps you safe by cutting the electricity supply should there be a malfunction like a power cut.
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HOUSE CIRCUITRY KEY 1 2 3 4 5 6
Meter Fusebox Outside Socket Lightswitch Fused Connection Unit Outlet Socket
METER
An electricity meter keeps tabs on your household’s electricity consumption,.
Electricity in Numbers
FUSED CONNECTION UNIT (FCU)
This wall-mounted fitting enables a device like an extractor fan to be plumbed directly into the power circuit, rather than via a plug and socket. It works off a switch.
OUTSIDE SOCKET
Sockets located outdoors are generally waterproof and may also feature a high sensitivity residual current circuit breaking to prevent electric shocks.
20.3 21.3 $133 %
%
of worldwide electricity is supplied by renewable sources of power.
of the world’s electricity is generated by China.
per household is wasted every year by appliances left on standby.
54kWh
175kWh
54TWh
of electricity is the average amount a person in Ethiopia consumes per year.
APRIL 2013
of electricity is used by an energy-saving light bulb in a year.
of electricity is consumed around the word every 24 hours.
HOW IT WORKS
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