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

Drift velocity `v_(d) = (I )/(nAe )`
`((vd)_("electron"))/((vd)_("hole"))=((I_(e))/(I_(h)))((n_(h))/(n_(e)))=(7)/(4) xx (5)/(7)=(5)/(4)`
Hence, the ratio of their drift velocities is `(5)/(4)`