Question

The stopping potential for the photoelectrons emitted from a metal surface of work function $1.7eV$ is $10.4V$. Find the wavelength of the radiation used. Also identify the energy levels in hydorgen atom which will emit this wavelength.

Answer 1

Given,

Work function energy $W=1.7ev$

Stopping Potential $K=10.4V$

We know that

$K_{max}=\frac{hc}{\lambda }-W$

Substitute all value in above equation

$10.4=\frac{hc}{\lambda }-1.7\lambda =\frac{hc}{10.4+1.7}=\frac{hc}{12.1}\frac{hc}{△E}=\frac{hc}{12.1}△E=12.1ev$

$\lambda =\frac{12375}{12.1}=1022.7A^0$

Energy level will be $n=3$ to $n=1$