The work function of a certain metal is 1.90 eV. What is the longest wavelenght of light that can?

Question

cause photoelectron emission from this metal?

a) 653 nm
b) 14.0 nm
c) 344 nm
d) 231 nm

Answer 1

The lowest energy of light that can overcome the work function is 1.9 eV. The energy of a photon of wavelength L is given by 1240 (nm)* eV / L (nm)

L = 1240/1.9 = 653 nm