Question

The work function of Li is 2.42 eV. Find the maximum

wavelength of electromagnetic radiation that can cause

photoemission from it.​

Answer 1

Explanation:

maximum wave length corresponds to minimum energy

from the concept of photo electric effect we know that the minimum energy

required to eject an electron from the metal surface is it work function

. ......so by using planks energy quantisation fromula

E=hc/lambda

where E is the work function

lambda is wave length of the incident light

lambda=(1240eV-nm)/E(in eV)

so lambda (maximum)=496nm