Question

Semiconductor is opaque for light of wavelength less than 800 nm and it is not opaque for light of wavelength greater than 800 nm. Energy gap of semiconductor in electron volt is [Take $hc=1240eV-nm$](Answer up to two decimal places)

Answer 1

Energy gap:
$E_g=\frac{hc}{\lambda }=\frac{1240eV-nm}{800nm}$

$E_g=1.55eV$