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

Answer

C

Explanation

`I=n_(e)Av_(d)`
`(I_(e))/(I_(n))=(n_(e)xx(v_(d))_(e))/(n_(h)xx(v_(d))_(h)) ` Here, `(n_(e))/(n_(h))=(7)/(5), (I_(e))/(I_(h))=(7)/(4)`
`therefore (7)/(4)=(7)/(5)xx((v_(d))_(e))/((v_(d))_(h)) rArr ((v_(d))_(e))/((v_(d))_(h))=(5)/(7)xx(7)/(4)=(5)/(4)`