Q. If the ratio of the concentration of electron to that of holes in a semiconductor is $\frac{7}{5}$ and the ratio of current is $\frac{7}{4}$, then what is the ratio of their drift velocities
A) $\frac{4}{5}$
B) $\frac{5}{4}$
C) $\frac{4}{7}$
D) $\frac{5}{8}$
Explanation
(b) $i = neAv_{d} \Rightarrow \frac{\left( v_{d} \right)_{e}}{\left( v_{d} \right)_{h}} = \frac{i_{e}}{i_{h}} \times \frac{n_{h}}{n_{e}} = \frac{7}{4} \times \frac{5}{7} = \frac{5}{4}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.