One day, Georg Simon Ohm did an experiment. He built a voltaic pile – what we would now call a battery. To judge the voltage, he attached a wire to each end, held one in his hand and touched the other to his tongue. Ouch! He did notice one interesting thing. If he stuck with copper wires and he went to a larger wire, his tongue hurt more! I am not making this up! You can Google it. 

That told him there must be some relationship between the size of the wire and the voltage running down that wire. He soon realized that this could be described in a formula, the formula we now call Ohm’s Law. He told this to his scientific friends and they were aghast! The idea that there was a relationship between voltage and current and the size of the wire (resistance) was so controversial, that they begged him not to reveal it. And so these results were not published until his death. It is pretty much the same story as Copernicus and the sun-centered planets. And we’re still using Ohm’s Law today. Read more »