I know that an electron gun releases electrons by thermionic emission and accelerate the electron through charged plates, and that the electrons are not gaining any energy after they leave the gap between the plates. I'm confused about charges/potentials around the charged plates.
If you have two charged plates, one negative and one positive using an EHT, and earth the cathode. If you place an electron just next to the anode, not between the plates, what would happen to the electron? Well I'm told that it wouldn't move, but why?
I was also told that the field lines cancel outside the plates (given the plates are infinitely long and one of the plates are earthed) but why? If we say the surroundings are neutral, and earth the cathode, surely the field lines from the anode won't be cancelled, because the cathode is neutral?