A few questions about electric field here: Why do charges have to be on the outer surface of the conductor? Why no charge on the inner surface of a hollow conductor? If charges c …

I've got a magnet of a determinate radius and a coil. Which radius should i give to the coil (in function of magnet radius) in order to obtain the maximum intensity? I think that …

The formula for calculating the strength of the electric field bewteen 2 flat bar conductors parallel to each other is E = -dV/dx. What does dx stand for? Is it the separation dist …

I was puzzling the Levitron today, and was trying to figure out what the magnets involved strength was, on the off chance that I may build a larger one for kicks. However, after s …