Question

If $\lambda$ is the wavelength of incident radiation of intensity $I$, calculate no. of photons incident per second on an area $A$.

• A. $\frac{IA\lambda }{hc}$
• B. $\frac{IA}{hc}$
• C. $\frac{hc}{IA\lambda }$
• D. $\frac{I\lambda }{hAc}$

Answer 1

The correct option is A $\frac{IA\lambda }{hc}$

Energy is given by, $E=I\cdot A$

$\therefore IA=\frac{hc}{\lambda }\times n$
$\Rightarrow n=\frac{IA\lambda }{hc}$

Hence, $\left(A\right)$ is the correct answer.