Question

20. The value of retarding potential needed to stop the
photoelectrons ejected from a metal surface of work
function 1.2 eV with light of energy 2 eV is

(a) 3.8 V
(b) 1.8 V (c) 2.8 V (d) 0.8 V​

Answer 1

Answer:

Here It should be noted that work done by retarding potential is equal to max kinetic energy of of photoelectrons

this eV =

$\frac{1}{2} {mv}^{2} = hv - workfunction$