Question

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

• A. ${10}^{10}$
• B. ${10}^{20}$
• C. ${10}^{30}$
• D. ${10}^{40}$

Answer 1

Answer: (C)

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