aha moments

I have been pleased to get a few aha moments out of my undergrads this semester in the small, advanced NYU E&M II class I am teaching. The best was when we looked at the Poynting vector in a highly symmetrical ribbon-like circuit with a perfectly cylindrical resistor and we could see the power flowing from the battery to the resistor in the pure field geometry. That's nice! The point of the class is radiation, primarily, so we are about to start really doing that to death.