Question

A metal ball is illuminated by ultraviolet radiation of wavelength 200 nm. The work function of the metal is $2eV.$ The electric potential acquired as a result of photoelectric effect is:

• A. $4.2V$
• B. $3.2V$
• C. $1.2V$
• D. data insufficient

Answer 1

The correct option is A $4.2V$

$\lambda$, wavelength $=200$nm

Work function $\varphi =2eV$

Energy of ultraviolet radiation $E=\frac{hc}{\lambda }$

$=\frac{6.626\times {10}^{-34}\times 3\times {10}^8}{200\times {10}^{-9}\times 1.6\times {10}^{-19}}$

$=6.211$ eV

Stopping potential $=6.2-2=4.2$V

Option A is correct.