If the ratio of the concentration of electrons to that of holes in a semiconductor is $\frac{7}{5}$ and the ratio of currents is $\frac{7}{4}$, then what is the ratio of their drift velocities?
Answer & explanation
Correct answer: option 3
$\frac{I_e}{I_h}=\frac{n_eeAv_e}{n_heAv_h}⇒\frac{7}{4}=\frac{7}{5}×\frac{v_e}{v_h}=\frac{5}{4}$