Question

If an LED has to emit $662$nm wavelength of light them what should be the band gap energy of its semiconductor? $h=6.62\times {10}^{-34}$Js.

Answer 1

Given:

$\lambda =662nm$

As

Energy gap$=E=\frac{hc}{\lambda }$

$E=\frac{6.62\times {10}^{-34}\times 3\times {10}^8}{662\times {10}^{-9}}$ (as $c=3\times {10}^8$)

$E=3\times {10}^{18}V$

Hence the correct answer $=3\times {10}^{18}V$