"We're going to talk about again some new concepts. And that's the concept of electrostatic potential electrostatic potential energy. For which we will use the symbol U and independently electric potential.

Which is very different, for which we will use the symbol V. Imagine that I have a charge Q one here and that's plus, plus charge, and here I have a charge plus Q two and they have a distant, they're a distance R apart. And that is point P. It's very clear that in order to bring these charges at this distance from each other I had to do work to bring them there because they repel each other.

It's like pushing in a spring. If you release the spring you get the energy back..."