# Kinetic energy of the emmited electrons

1. Nov 27, 2004

### WAHEEDA

(1) The work function of a particular metal is 2.00 eV.
(a) If the metal is illuminated with monochromatic light of wavelength 550 nm, what will be the maximum kinetic energy of the emmited electrons and,
(b) their maximum speed?
(c) What is the required stopping potential?
(d) What are the threshold frequency and corresponding wavelength for
the metal?

(2) A potential difference of 40kV is applied across an X-rays radiated?

please I need help..and need the answer by this coming monday,29th november 2004!!!!

Last edited by a moderator: Oct 18, 2016
2. Nov 27, 2004

### chroot

Staff Emeritus
The work function is the amount of energy required to remove an electron from a metal. The amount of energy contained in a photon of light of frequency v is E = hv. Some of that energy is used to liberate the electron from the metal; the rest ends up as kinetic energy of the electron. You should be able to calculate the speed from the kinetic energy.

- Warren