Light of energy 5eV falls on a metal of work function 3eV and electrons are liberated. The stopping potential is
A
1.7V
B
2.0V
C
8.0V
D
15.0V
Verified Correct Answer: B.
Physical Principles & Numerical Solution
For a photoemitted electron,
eV = K.E.max, where V = stopping potential and K.E. = maximum kinetic energy of the photo emitted electron given by K.E. = Energy of incident rad - Work function
= 5ev - 3ev = 2ev
∴ eV = 2eV
V = 2eV/e = 2V
∴ Stopping Potential = 2.0V
Source: Myschool Past Questions Archive (Record #1503)