Question

calulate the energy of 100photons if the wave length of the light is 2000A

Answer 1

Hello!

♦ Frequency = $\dfrac{\sf c}{\sf \lambda}$

= $\dfrac{\sf 3\: x\: 10^{8} \:ms^{-1}}{\sf 2000\:x\: 10^{-10}\: m}$

= $\sf 1.5 \:x\: 10^{15}\: s^{-1}$

♦ Energy = $\sf hV$

= $\sf 6.626\:x\:10^{-34} \:Js^{-1} \:x\: 1.5\: x\: 10^{15} \: s^{-1}$

Then,

$\textbf{Energy\: of \:100 \:photon}$ = $\boxed{\sf 9.94 \:x\: 10^{-17}}$

Cheers!