Question

Photoelectric Effect Question:

Part 1: From the equations compute the potential you need to apply to stop electrons when the light is at 400nm. Repeat the same for 250 nm.

Part 2: Hypothetically, why are these potentials different from the stopping potentials?

Answer 1

Point to be noted that these potentials are all negative potentials. To stop an electron, we need negative potential.

Part 2:

Hypothetically these potentials are different from stopping potentials because there are another factor which is called 'Work Function' and due to this work function there are some energy lose of input light.