Question

Work function of a photo-sensitive metal is $3eV$. The wavelength of incident radiations which can just eject photo-electrons from the metal is

• A. $600nm$
• B. $510nm$
• C. $414nm$
• D. $378nm$

Answer 1

Answer: (C)

$414nm$

Work function of the metal $\varphi =3eV$

Wavelength of incident photon just eject photo electrons $\lambda =\frac{hc}{\varphi }$

where $hc=1242eV$ and $\lambda$ is in $nm$.

$\therefore$ $\lambda =\frac{1242}{3}nm=414nm$