# SIGNALS

## Ω: The Story of Ohm's Law

Ohm's law describes the essential, bedrock principle upon which rests all things electrical. Consider the world around you. Everything that has electricity running through it owes its existence to this principle. And Georg Ohm was the guy who mathematically described it. Ohm's law. Pure genius. His contemporaries despised him.

In the first hour of the first class of the first course of any electrical engineering curriculum, the teacher writes this on the blackboard: V = IR. Students, at least the ones who bother to glance up from their phones, dutifully write this down in their notebooks. From this origin, in a few years, these students, at least the ones who looked up from their phones, will be engineers designing and building computers and space ships and all sorts of wondrous things. They can do this because they learned that V = IR.

Voltage equals current times resistance. That expression is called Ohm's law because it was Georg Ohm who first proposed it in 1827. The expression is entirely correct, and entirely obvious to us today, but in Ohm's day, his proposal was met with considerable hostility. His theory ran contrary to settled science in Germany at that time. Ohm's contemporaries thought it was a crackpot idea and in fact Ohm was professionally ostracized and became the target of considerable derision. The remarkable story is described in this excellent YouTube video.

Part of the opposition to Ohm's law stemmed from the fact that it was probably misunderstood because his expression of it was highly mathematical and at best, arcane. This made it doubly hard for contemporaries to accept a novel idea that already ran contrary to their expectations. In addition, some contemporaries dismissed his empirical proof because they believed in an ordered universe that was best understood with pure reasoning. Along these lines, one critic called his work, “an incurable delusion whose sole effort is to detract from the dignity of nature.”

Of course, eventually, reality alone prevails. As scientists and inventors expanded their understanding of electricity and its applications, they began to appreciate how Ohm's expression exactly described their laboratory results, and how it perfectly predicted the working of their inventions. It took more than a decade after his paper was published, but Ohm's law was slowly embraced by the scientific and engineering communities and recognized as the correct expression for the interaction of voltage, current, and resistance. Later in the century, Ohm's law formed the basis of circuit theory which, of course, was the beginning of our modern world.

Georg Ohm did not live to see it, but to recognize his work, the unit of electrical resistance, the ohm, was named in his honor. It is notated with the Greek letter Ω.

Postscript: While many contemporaries condemned Ohm's work, his chief nemesis was a scientist named Georg Pohl. Among other aspersions, he said of Ohm, “A physicist who professes such heresies is unworthy to teach science.” Profoundly discouraged, Ohm resigned from his university teaching position. I do not know if Georg Pohl has any part in my own family tree, but if he does, I sincerely apologize because, in fact, V = IR.

Post Postscript: BBROYGBVGW