Q. The contribution in the total current flowing through a semiconductor due to electrons and holes are $\frac{3}{4}$ and $\frac{1}{4}$ respectively. If the drift velocity of electrons is $\frac{5}{2}$ times that of holes at this temperature, then the radio of concentration of electrons and holes is
A) 6 : 5
B) 5 : 6
C) 3 : 2
D) 2 : 3
Explanation
(a) As we know, current density $J = nqv$
$\Rightarrow$ $j_{e} = n_{e}{\ qv}_{e}$
and $J_{h} = n_{h\ }{qv}_{h}$
$\frac{j_{e}}{J_{h}} = \frac{n_{e}}{n_{h}} \times \frac{v_{e}}{v_{n}}$
$\Rightarrow \frac{\frac{3}{4}}{\frac{1}{4}} = \frac{n_{e}}{n_{h}} \times \frac{5}{2}$
$\Rightarrow \frac{n_{e}}{n_{h}} = \frac{6}{5}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.