Question

Calculate the energy of $100$ photons if the wavelength of the is $2000A$.

Answer 1

Given $\lambda =2000\stackrel{o}{A}$

$E=h\gamma$

$=\frac{hC}{\lambda }$ $h=6.626\times {10}^{-34}Js,C=3\times {10}^{8}m/s$

Energy of $100$ photons,

$=\frac{100\times 6.626\times {10}^{-34}\times 3\times {10}^8}{2000\times {10}^{-10}}$

$\Rightarrow 0.99\times {10}^{-16}J=9.9\times {10}^{-17}J$