Q. The maximum wavelength of radiation that can produce photoelectric effect in certain metal is 200 nm. The maximum kinetic energy acquired by electron due to radiation of wavelength 100 nm will be
A) 12.4 eV
B) 6.2 eV
C) 100 eV
D) 200 eV
Explanation
(b) Here, $\lambda_{0} = 200nm;\ \lambda = 100nm;$
$hc/e\ = \ 1240eV\ nm$
maximum KE $= \frac{hc}{\lambda e} - \frac{hc}{\lambda_{0}e}(in\ eV)$
$= \frac{hc}{e}\left( \frac{1}{\lambda} - \frac{1}{\lambda_{0}} \right)$
$= 1240\left( \frac{1}{100} - \frac{1}{200} \right)$
$= 6.2\ eV$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.