If the ratio of the concentration of electron to that of holes in a semiconductor is `(7)/(5)` and the ratio of current is `(7)/(4)` then what is the ratio of their drift velocities ?

Options

A. `(4)/(7)`
B. `(5)/(8)`
C. `(4)/(5)`
D. `(5)/(4)`

Answer

D

Explanation

Given, `(n_(e))/(n_(h))=(7)/(5),(I_(e))/(I_(h))=(7)/(4)`
Drift velocity, `v_(d)= (I)/(nAe),v_(d) prop (I)/(n)`
`therefore" "((v_(d))_(e))/((v_(d))_(h))=(I_(e))/(I_(h))xx(n_(h))/(n_(e))=(7)/(4)xx(5)/(7)=(5)/(4)`