Question

Photoelectric effect experiment are performed using three different metal plates (x, y, z) having work function equal to 2.0 eV, 2.5 eV and 3.0 eV, respectively. A light beam, containing wave length of 550 nm, 450 nm and 350 nm, having equal intensity of illumination, is incident on each of the three plates. The correct I–V graph, of the three cases, is the graph numbered as graph. 

(1) A 

(2) B 

(3) C 

(4) D

Answer 1

Correct option :  (4)

Explanation : 

We have: Energy of a photon (in eV) 

Thus it is clear E₁ cannot emit photoelectrons from y and z plates E₂ cannot emit photoelectrons from z plate. 

Also work function of x is least and it can emit photoelectrons for all the three wavelengths. Hence magnitude of the stopping potential, and saturation current both, will be maximum, for metal plate x.