Question

A potassium metal has a work function F = 4.41 x 10-19 J. Calculate the velocity of electrons emitted by exposing the metal to radiation of wavelength 300 nm.

Answer 1

calculate the incoming radiation energy=Planck'sConstant*speelight/wavelength

then subtract the work function.
Then convert the remaining energy to 1/2 m v^2, and find v.