Q. The wavelength of a 1 keV photon is $1.24 \times 10^{- 9}$m. What is the frequency of 1 MeV photon?
A) $2.4 \times 10^{15}$Hz
B) $2.4 \times 10^{20}$Hz
C) $1.24 \times 10^{15}$Hz
D) $1.24 \times 10^{20}$Hz
Explanation
(b) $hc/\lambda\ = 10^{3}\ eV$ …(i)
$hv = 10^{6}eV$ …(ii)
Dividing Eq.(ii) by Eq. (i) we get, $v = 10^{3}c/\lambda$
$= 10^{3} \times 3 \times 10^{8}/1.24 \times 10^{- 9} = 2.4 \times 10^{20}$Hz
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.