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.