Correct Answer - C
Suppose an electron enters the depletion layer with Speed `v_1` and p-region with speed `v_2`, as shown in figure.
Its potential energy increased by eV joule. By energy conservation,
`1/2mv_2^2+eV=1/2mv_1^2 " " or " " 1/2mv_2^2=1/2mv_1^2-eV`
`=1/2xx9.1xx10^(-31)(5.0xx10^5)^2-1.6xx10^(-19)xx0.50`
`=(1.13-0.8)xx10^(-19)=0.33xx10^(-19) J`
`therefore v_2^2=(2xx0.33xx10^(-19))/m=(0.66xx10^(-19))/(9.1xx10^(-31))=7.25xx10^10`
or `v_2=2.7xx10^5 m s^(-1)`.