Question

An AIR station is broadcasting the waves of wavelength 300 metres. If the radiating power of the transmitter is 10 kW, then the number of photons radiated per second is

• A. $1.5\times {10}^{29}$
• B. $1.5\times {10}^{31}$
• C. $1.5\times {10}^{33}$
• D. $1.5\times {10}^{35}$

Answer 1

The correct option is B

$1.5\times {10}^{31}$

$p=\frac{W}{t}=\frac{nhc}{\lambda t}\Rightarrow \left(\frac{n}{t}\right)=\frac{p\lambda }{hc}=\frac{10\times {10}^3\times 300}{6.6\times {10}^{-34}\times 3\times {10}^8}$
$=1.5\times {10}^{31}$