Terms in Currency

You don’t have to be a football expert to sit in the stands on a nice fall day and watch the locals bash the visitors. But to get the most from the festivities, it helps to know the difference between a two-point conversion and an on-side kick. Being able to converse with your seatmates about the nickel defense and the single-wing offense surging back and forth before your eyes makes it even better. The jargon isn’t just for the players and sportscasters.

Electricity is a bit like that. Most of us are users, and most of us know some of the jargon despite the fact we don’t work at a power plant. We know that we have 12-volt batteries in our cars and that the porch light takes a 60-watt light bulb. And for many folks, that’s enough.

I believe, however, that those of us who work with things electric on a larger scale can benefit from knowing a little more. And I find that many people gain a better understanding of even the most technical concepts when they are given some background information on the bits and pieces – the jargon that makes it all happen.

NAME GAMES

Four of the biggest bits and pieces in electricity are volt, ampere, ohm and watt. Take a moment and just look at those four words: If they weren’t familiar to us on some level, they might appear to be made up. Play words. In fact, each is derived from the name of a person – and it’s quite a group:

[ ] Count Alessandro Guiseppe Antonio Anastasio Volta (1745-1827). An Italian physicist, he’s famous for his work with static electricity and various means of storing electric charges. Along the way, he invented the battery.

[ ] Andre Marie Ampere (1775-1836). A French physicist and mathematician, he was known primarily for his contributions to electrodynamics and his research into the relationship between electricity and magnetism. He formulated the basic law of electromagnetism, commonly called Ampere’s Law.

[ ] Georg Simon Ohm (1787-1854). A German physicist, his studies of electric current led to the formulation of Ohm’s Law, which defines the mathematical relationships between the various elements of current flow.

[ ] James Watt (1736-1819). A Scottish inventor, he had absolutely nothing to do with electricity. He was, however, a mechanical genius responsible for improving the steam engines of his time and had a significant role in the industrialization of the world.

Over the years, various scientific and government committees have honored these men by assigning their names to units of measurement. In the United States, we use two major systems of measurement, side by side: the U.S. Customary System, which is based upon the British Imperial System; and the International System of Units, referred to as “SI,” from the French term, Systeme International.

The Customary System includes such familiar terms as acres, ounces and pounds, feet and miles, quarts and gallons, pecks and bushels. We’re comfortable with these old friends, and they serve us well in our everyday lives. For their part, SI units include all of the technical terms used worldwide – kilogram, meter, ampere, second, volt, ohm, watt, joule, coulomb, lumen, degrees Celsius and several others.

This is the modernized system that most people are referring to when they say “the metric system.” In its current form, it is the most accurate and versatile system of measurements ever devised.

MEASURING UP

Before we use the tools the SI system provides us to define, describe, measure and compare all things electric, we need to back up and take a look at electricity itself.

Electricity is a lot like gravity: We know it’s there, we can see and feel its effects, we can describe and label its various aspects – but we’re really not sure what it is. Only in this century, in fact, have scientists recognized that there are four fundamental natural forces: gravity, electromagnetism, the strong nuclear force and the weak nuclear force. By calling them “fundamental forces,” we can stop worrying so much about what causes them to exist and direct our efforts toward making them work for us.

Along those same lines, a closer look at electricity forces us to look at atoms, and inside the atoms to electrons.

Atoms are the smallest unit of any element, consisting mainly of empty space with a positively charged nucleus at the center and one or more negatively charged electrons orbiting some distance away.

All of the electrons are basically the same. In fact, the primary difference between one element and another is not that the electrons are different from each other; rather, it is a matter of the number of electrons it has that makes each element unique. An atom of the element hydrogen has one electron, for instance, while a chlorine atom has 17 electrons and an atom of lead has 82.

The smallest particles known to have an electrical charge, electrons are about as small as things get. If you could line up about 125,000,000 atoms – any atoms, it doesn’t matter which ones – and pack them tightly, side by side, the group would measure about an inch long. Now, zoom in on a single one of those atoms until it appears to be the size of a football field: The nucleus would be the size of a small grape sitting on the 50-yard line and, as small as that grid might be, the grape/nucleus is about 2,000 times larger than the electrons orbiting around the stadium.

In other words, electrons are small, and they are very plentiful.

The SI unit “coulomb” provides us with a convenient way to get rid of some of the very large numbers involved. A coulomb is the basic unit of electric charge, containing 6.24 billion billion electrons. (It’s much more impressive written out as 6,240,000,000,000,000,000.)

If you like the water flow/electric-current flow analogy, think of electrons as the equivalent to molecules of water and the coulomb as the equivalent of a gallon and then inject time into the equation: Gallons per minute is well understood for water flow; the analogous unit on the electrical side would be coulombs per second. Conveniently, that already has a name of its own: ampere. (Thank you, Andy.)

So when we talk about current flowing in a circuit, we’re talking about the flow of electrons, and we measure the quantity of that flow in amperes, just as we use gallons per minute to describe water flow.

Why does the current flow? We’ll tackle that in the next issue, and also learn more about Count Al, Georg and wee Jimmy Watt.

Jim McNicol was a technical consultant to the swimming pool, jetted bath and spa industries. He worked on development of equipment standards for pools and spas throughout his career and was honored for his service by the National Spa & Pool Institute.