Q129 / 180 · COMEDK 2023 (Memory Based) · Physics
A transistor is connected in $\mathrm{CE}$ configuration. The collector supply is $10 \mathrm{~V}$ and the voltage drop across a resistor of $1000 \Omega$ in the collector circuit is $0.5 \mathrm{~V}$. If the current gain factor is 0.96 , then the base current is
- A$25 \mu \mathrm{A}$
- Correct answerB$20.8 \mu \mathrm{A}$
- C$22.5 \mu \mathrm{A}$
- D$15 \mu \mathrm{A}$
Solution
Current gain factor, $\alpha=0.96$
$R=1000 \Omega$, Voltage drop across collector resistor $=0.5 \mathrm{~V}$
$\therefore \quad \beta=\frac{\alpha}{1-\alpha}=\frac{0.96}{1-0.96}=24$
$\therefore$ Collector current,
$\begin{aligned}
i_c & =\frac{\text { Voltage drop across collector resistor }}{R} \\
& =\frac{0.5}{1000}=0.5 \times 10^{-3} \mathrm{~A}
\end{aligned}$
The base current, $i_b=\frac{i_c}{\beta}=\frac{0.5 \times 10^{-3}}{24}=20.8 \mu \mathrm{A}$
Hence, the correct answer is option: 'B'.