Answer to Question #180559 in Electric Circuits for Dion Gray

Question

A metal is connected as the emitter in a photoelectric effect experiment. Light with wavelength 831nm strikes the metal. Is there a minimum potential difference that can be applied to ensure that there is no current in the circuit due to the movement of photoelectrons to the collector?

Answer 1

When the power supply is set to a low voltage it traps the least energetic electrons, reducing the current through the microammeter. Increasing the voltage drives increasingly more energetic electrons back until finally none of them are able to leave the metal surface and the microammeter reads zero. The potential at which this occurs is called the stopping potential. It is a measure of the maximum kinetic energy of the electrons emitted as a result of the photoelectric effect.