MCQ
In common base circuit of a transistor, current amplification factor is 0.95 . Calculate the emitter current if base current is $0.2 mA$.
- A$2 mA$
- ✓$4 mA$
- C$6 mA$
- D$8 mA$
✓
Answer
Correct option: B.
$4 mA$
(b) : Here, $\alpha=0.95$,
As $\alpha=\frac{I_C}{I_E}=0.95$
$I_B=0.2 mA$
$\therefore \quad I_C=0.95 I_E$
$
\begin{aligned}
& \text { As } I_E=I_B+I_C \\
& \therefore \quad I_E=I_B+0.95 I_E \Rightarrow 0.05 I_E=I_B \\
& I_E=\frac{I_B}{0.05}=\frac{0.2 mA }{0.05}=4 mA
\end{aligned}
$
As $\alpha=\frac{I_C}{I_E}=0.95$
$I_B=0.2 mA$
$\therefore \quad I_C=0.95 I_E$
$
\begin{aligned}
& \text { As } I_E=I_B+I_C \\
& \therefore \quad I_E=I_B+0.95 I_E \Rightarrow 0.05 I_E=I_B \\
& I_E=\frac{I_B}{0.05}=\frac{0.2 mA }{0.05}=4 mA
\end{aligned}
$
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