Question

Two sources of light emit with a power of 200 W. The ratio of number of photons of visible light emitted by each source having wavelengths 300 nm and 500 nm respectively, will be:

(1) 1 : 5 

(2) 1 : 3 

(3) 5 : 3 

(4) 3 : 5

Answer 1

The correct option is (4) 3 : 5.

\(n_1 \times \frac{hc}{\lambda_1} = 200\)

\(n_2 \times \frac{hc}{\lambda_2} = 200\)

\(\frac{n_1}{n_2} = \frac{\lambda_1}{\lambda_2} = \frac{300}{500}\)

\(\frac{n_1}{n_2} = \frac{3}{5}\)