Question

A radio transmitter radiates $1 \,kW$ power at a wavelength $198.6\, m$. How many photons does it emit per second?

• A. $ \text{1}{{0}^{\text{1}0}} $
• B. $ \text{1}{{0}^{\text{2}0}} $
• C. $ \text{1}{{0}^{\text{3}0}} $
• D. $ \text{1}{{0}^{\text{4}0}} $

Answer 1

Answer: (C)

$ n=\frac{P}{E}=\frac{P}{hv}=\frac{P\lambda }{hc} $
$ =\frac{1000\times 198.6}{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}\approx {{10}^{30}} $