Question

There are two sources of electromagnetic waves, each emitting with a power of 100 W. one emits X – rays of wavelength 1 nm & the other visible light at 500 nm. The ratio of the number of photons of X – rays to the photons of visible light is

• A. 1 : 500
• B. 1 : 1000
• C. 500 : 1
• D. 1000 : 1

Answer 1

The correct option is A

1 : 500

$n_1{E}_1=n_2{E}_2$

$\Rightarrow n_1\frac{h_c}{{\lambda }_1}=n_2\frac{h_c}{{\lambda }_2}$

$\therefore \frac{n_1}{n_2}=\frac{{\lambda }_1}{{\lambda }_2}=\frac{1}{500}$