Question

lf a source of power $4kW$ produces ${10}^{20}$ photons/second, the radiation belong to a part of the spectrum called :

• A. $X$-rays
• B. Ultraviolet rays
• C. Microwaves
• D. $\gamma -$rays

Answer 1

The correct option is A $X$-rays

Power $=n\times$ Energy of Single Photon.

$4\times {10}^3={10}^{20}\times =h\upsilon$

$\upsilon =\frac{4\times {10}^3}{{10}^{20}\times 6.023\times {10}^{-4}}$

$\upsilon =6.03\times {10}^{16}$ Hz

The obtained frequency lies in the band of X-rays.