Question

A monochromatic light source of frequency $6\times {10}^{14}Hz$ is emitting energy at the rate $2\times {10}^{-3}J/s$. Calculate the number of photons emitted per second by the source.

Answer 1

Let the rate of photons emitted by source be $n$.

Energy of single photon=$h\nu$

Hence the power of emitted photons=$P=nh\nu$

$⟹n=\frac{P}{h\nu }$

$=\frac{2\times {10}^{-3}}{6.626\times {10}^{-34}\times 6\times {10}^{14}}photons/s$

$=5.03\times {10}^{15}photons/s$