OHM’s Law in the Wireless World

IT’S THE LAW

OHM’S LAW IN THE WIRELESS WORLD

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The old refrain, ‘when will I ever need algebra’ suddenly becomes a regretful choice of statement! Yet without Ohm’s Law, our industry likely wouldn’t exist as it does today.

When Alessandro Volta proposed that electricity wasn’t some ‘Star Wars’ type force in living beings, and went about proving it by inventing the battery, he set in motion the work of Georg Ohm.

Ohm understood that a mathematical application could be applied to determine the current flowing in an electrical circuit. In his ground-breaking paper, Die Galvanische Kette, Mathematisch Bearbeitet, Ohm proved mathematically that a directly proportional relationship existed between voltage and resistance and their impact on current flow.

This fundamental of electrotechnology theory provides a basis for many of the calculations used by electricians, technicians and engineers. For an electrician, Ohm’s Law is what einstein’s Law of Relativity is to a physicist. The simple equation allows us to calculate an unknown value, if the two other variables are known.

Whether voltage, current or resistance, any given two can be used to calculate the unknown quantity. For many apprentices, their first experience in electrical theory is based on calculating and then measuring volts, amps and ohms. As they finish their apprenticeship, the Capstone Assessment draws on those fundamental relationships, from the design, to testing and fault finding.

Yet we live in a time where there is ‘an App for everything’.

True as that is, being able to quickly and accurately use Ohm’s Law to determine the characteristics of an electrical circuit, without reaching for your phone, is a basic but essential skill all electricians need. In fact, the first ten essential performance capabilities required for electrical licensing in Australia all relate to Ohm’s Law.

Volt drop, current carrying capacity, insulation resistance – all require a working knowledge of Ohm’s Law. Certainly, modern calculators have made the math side easier, but when you find yourself up in a ceiling space, or in a switch room, a plant room or working on a bore pump in a paddock, using Ohm’s Law to determine a fault or to commission the system is still a must.

What about in a wireless world?

Where Bluetooth, Wi-Fi, nFC and other touchless technologies are booming, how does a law based on actual hardwired circuits still have relevance? We are still a long way off from ‘wireless’ power. Motors, transformers, apparatus and appliances still need an electrical supply. As we move from lower efficiency devices to higher efficiency ones, being able to resize cables, redesign control circuits and deploy new and emerging technologies, knowing how it was originally designed will remain an essential.

We stand on the cusp of a major shift in electrical use.

From World War II, power usage in Australia rose year on year. But in the last ten years, we have seen a focus on reducing our energy consumption. electricity prices no doubt play a part in this changed behaviour, but social and corporate responsibility have become increasingly powerful drivers in developing new ways to shrink our carbon footprints. LeD downlights, smart motor control, VFD/ VSDs, battery and inverter technology and hydrogen cells will all lead to a future of lower energy consumption.

Yet the underpinning theory for all this technology remains a simple three-part equation.

I=V/R.

Ohm’s Law – it is still relevant in a wireless world.

Steve Hall

General Manager, College of Electrical Training www.cet.asn.au

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