Q. If the wavelength of incident light changes from 400 nm to 300 nm, the stopping potential for photoelectrons emitted from a surface becomes approximately
A) 1.0 V greater
B) 1.0 V smaller
C) 0.5 V greater
D) 0.5 V smaller
Explanation
(a) $\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ E = \frac{hc}{\lambda} \Rightarrow E \propto \frac{1}{\lambda}$
$\Rightarrow \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ $ $\ \frac{E^{'}}{E} = \frac{400}{300} = 1.33$
But $E = eV_{s},\ V_{s}$ being stopping potential. Thus, stopping potential for photoelectrons from a surface becomes approximately 1.0 V greater.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.