Question

For a transistor $\frac{I_C}{I_E}=0.96$, then current gain for common emitter is

• A. 12
• B. 6
• C. 48
• D. 24

Answer 1

Answer: (D)

The current gain of a common emitter transistor $(\beta )$ is defined as the ratio of collector current $\left(I_C\right)$ to the base current $\left(I_B\right)$.
Also, $I_E=I_B+I_C;I_C/I_E=0.96$ (given)
$\therefore \beta =\frac{I_C}{I_B}=\frac{I_C}{I_E-I_C}$
Now, $\frac{I_E}{I_C}=\frac{1}{0.96}.$
$\therefore \frac{I_E-I_C}{I_C}=\frac{1}{0.96}-1=\frac{0.04}{0.96}$
$\therefore \beta =\frac{I_C}{I_E-I_C}=\frac{0.96}{0.04}=24\text{. }$