An LED is constructed from a p-n junction based on a certain Ga-As-P semiconducting material whose energy is 1.9 eV. What is the wavelength of the emitted light?

Options

A. 150 nm
B. 350 nm
C. 500 nm
D. 650 nm

Answer

D

Explanation

If `lambda ` is the wavelegth of emitted light, then
`E_g = (hc)/lambda rArr lambda =(hc)/(E_g)`
`=((6.63 xx 10^(-34))xx(3xx10^8))/((1.9)xx(1.60xx 10^(-19))) = 6.5 xx 10^(-7) m = 650 nm`