# Photoelectric Effect and Electromagnetism Voltage Problem

Whenever a book talks about the photoelectric effect, it talks about how we can use a battery to attain a $V_{stop}$. Basically, you are making the metal plate on which you don't shine light have a negative charge. This prevents the electrons from going from one plate to another.

Now, I do not understand why there is no current at $V_{stop}$. After all, the metal plate on which you shine light is positive. The electrons, being excited, would preferentially go to the positive side than to the negative side. So, should the direction of the current not be reversed rather than inexistent?

• In other words, how come the electrons don't travel in the opposite way? Why do they always have to come out of the surface? – yolo123 Nov 5 '14 at 4:09
• If when excited they do not have enough energy to go to the negative plate, falling back will balance the charge of the plate to where it was, thus no current. If they have enough energy to cross the charge on the unshined plate changes and current has to flow to reach the capacitor's equilibrium. – anna v Nov 5 '14 at 5:31