Question

When radiation is incident on a photoelectron emitter, the stopping potential is found to be 9 volts. If e/m for the electron is $1.8\times {10}^{11}Ck{g}^{-1}$ the maximum velocity of the ejected electrons is

• A. $6\times {10}^{5}m{s}^{-1}$
• B. $8\times {10}^{5}m{s}^{-1}$
• C. $1.8\times {10}^{6}m{s}^{-1}$
• D. $1.8\times {10}^{5}m{s}^{-1}$

Answer 1

The correct option is C

$1.8\times {10}^{6}m{s}^{-1}$

$\frac{1}{2}m{v}_{max}^2=e{V}_0\Rightarrow v_{max}=\sqrt{2\left(\frac{e}{m}\right)V_0}=\sqrt{2\times 1.8\times {10}^{11}\times 9}=1.8\times {10}^{6}m/s$