Question

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

• A. y-rays
• B. X-rays
• C. Ultraviolet rays
• D. Microwaves

Answer 1

The correct option is B X-rays

The correct option is B

given p=4000w

$E=\frac{hc}{\lambda }$

$\lambda =\frac{hc\times {10}^{20}}{4000}$

$=hc\times \frac{{10}^{17}}{4}$

$\lambda =3\times {10}^8\times 6.6\times \frac{{10}^{-34+17}}{4}$

$=19.8\times \frac{{10}^{-9}}{4}$

$=4.9\times {10}^{-9}$

$=49\times {10}^{-10}$

$=49\dot{A}$

Since,

$0.1\dot{A}<\lambda <100\dot{A}$

It is X-rays