Question

The number of photons of light having wave number ${}^{\prime }{x}^{\prime }$ in $10J$ of energy source is:

• A. $10hcx$
• B. $\frac{hc}{10x}$
• C. $\frac{10}{hcx}$
• D. None of these

Answer 1

The correct option is C $\frac{10}{hcx}$

$E=\frac{nhc}{\lambda }=nhc\overline{v}(\because \overline{v}=\frac{1}{\lambda })$
$\therefore 10=nhc\overline{v}orn=\frac{10}{hc\overline{v}}=\frac{10}{hcx}$