Feynman sobre eletricidade

"Consider a force like gravitation which varies predominantly inversely as the square of the distance, but which is about a billion billion billion billion times stronger. And with another difference. There aro two kinds of "matter", which we can call positive and negative. Like kinds repel and unlike kinds attract - unlike gravity where there is only attraction. What would happen?

A bunch of positives would repel with an enormous force and spread out in all directions. A bunch of negatives would do the same. But an evenly mixed bunch of positives and negatives would do something completely different. The opposite pieces would be pulled together by the enormous attractions. The net result would be that the terrific forces would balance themselves out almost perfectly, by forming tight, fine mixtures of the positive and negative, and between two separate bunches of such mixtures there would be practically no attraction or repulsion at all.

There is such a force: the electrical force. And all matter is a mixture of positive protons and negative electrons which are attracting and repelling with this great force. So perfect is the balance, however, that when you stand near someone else you don't  feel any force at all. If there were even a little bit of unbalance you would know it. If you were standing at arm's length from someone and each of you had one percent more electrons than protons, the repelling force would be incredible. How great? Enough to lift the Empire State Building? No! To lift Mount Everest? No! The repulsion would be enough to lift a "weight" equal to that of the entire earth!"

Ótima introdução sobre eletricidade no Feynman Lectures on Physics II. Sugiro fortemente a leitura para quem, como eu, gosta de ciência.