Q. The ratio of electron and hole current in a semiconductor is 7/4 and the ratio of drift velocities of electrons and holes is 5/4, then ratio of concentrations of electrons and holes will be
A) 5/7
B) 7/5
C) 25/49
D) 49/75
Explanation
(b) $I = nAev_{d}\ \ or\ \ \ I \propto nv_{d}$
$\therefore\ \frac{I_{e}}{I_{h}} = \frac{n_{e}v_{e}}{n_{h}v_{h}}$
or $\frac{n_{e}}{n_{h}} = \frac{I_{e}}{I_{h}} \times \frac{v_{h}}{v_{e}} = \frac{7}{4} \times \frac{4}{5} = \frac{7}{5}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.