Question

The contribution in the total current flowing through a semiconductor due to electrons and holes are <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> $\frac{3}{4}$ and <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> $\frac{1}{4}$ respectively. If the drift velocity of electrons is <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> $\frac{5}{2}$ times that of holes at this temperature, then the ratio of concentration of electrons and holes is

• A. $6:5$
• B. $5:6$
• C. $3:2$
• D. $2:3$

Answer 1

The correct option is A $6:5$

The current density is given by,
$J=nq{v}_d$
$\Rightarrow \frac{J_e}{J_h}=\frac{n_e}{n_h}\times \frac{(v_d{)}_e}{(v_d{)}_p}$

$\frac{\left(\frac{3}{4}\right)}{\left(\frac{1}{4}\right)}=\frac{n_e}{n_h}\times \frac{5}{2}$

$\therefore \frac{n_e}{n_h}=\frac{6}{5}$

Hence, $\left(A\right)$ is the correct answer.