Hi I have a quick question about photoelectric effect. How do I measure the ratio of velocities of electrons ejected from surface of Aluminum and Caesium , after having those surfaces illuminated with a 250 nm monochromatic light. Which formula to derive it from?

Question

Hi I have a quick question about photoelectric effect. How do I measure the ratio of velocities of electrons ejected from surface of  Aluminum and Caesium , after having those surfaces illuminated with a 250 nm monochromatic light.  Which formula to derive it from?

jamesj · Answer

You know the energy level of the incident photons.

You also know for the Al and Caesium atoms the ionization energy and hence the energy of each ejected photon is

E = (Energy of incident photon) - (Ionization energy)

From that E, which must be all kinetic energy, you can calculate the velocity.