Q. If source of power 4 kW produces $10^{20}$ photon/ second, the radiation belong to a part of the spectrum called
A) X-rays
B) Ultraviolet rays
C) Microwaves
D) $\gamma$-rays
Explanation
(a) $4 \times 10^{3} = 10^{20} \times hf$
$f = \frac{4 \times 10^{3}}{10^{20} \times 6.023 \times 10^{- 34}}$
$\ f$ = 6.64$\times 10^{16}$ Hz
The obtained frequency lies in the band of X-rays.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.