Question

If a source of power $4$ kW produces ${10}^{26}$ photons/second, the radiation belongs to a part of the spectrum called:

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

Answer 1

The correct option is C Microwaves

$4000J$ of energy is produced from ${10}^{26}$ photons in one second.

Energy of each photon $E=\frac{4000}{{10}^{26}}=4\times {10}^{-23}J$

Frequency of each photon $\nu =\frac{E}{h}=\frac{4\times {10}^{-23}}{6.63\times {10}^{-34}}=6\times {10}^{10}Hz$

So the radiation belongs to micro waves.

Correct answer is option C.