Question

There are two source of light, each emitting with a power of 100 W. One emits X-rays of wavelength 1 nm and the other visible light of 500 nm . The ratio of number of photons of visible light of the given wavelength is:

• A. 1:500
• B. 1:400
• C. 1:300
• D. 1:200

Answer 1

Answer: (A)

1:500

Answer 2

: Here p =100 W, $\lambda_{1} = 1nm,\lambda_{2} = 500nm$

Let $n_{1}$and $n_{2}$be the number of photon of X-rays and visible light emitted from the two sources

$\therefore n_{1}\frac{hc}{\lambda_{1}} = n_{2}\frac{hc}{\lambda_{2}}$

Or $\frac{n_{1}}{\lambda_{1}} = \frac{n_{2}}{\lambda_{2}}or\frac{n_{1}}{n_{2}} = \frac{\lambda_{1}}{\lambda_{2}} = \frac{1}{500}$