Question

In a common-base amplifier circuit, calculate the change in base current if that in the emitter current is 2mA and $\alpha$= 0.98

• A. 0.04 mA
• B. 1.96 mA
• C. 0.98 mA
• D. 2 mA

Answer 1

The correct option is C 0.98 mA

In common base amplifier,
$\alpha =\frac{\Delta I_C}{\Delta I_E}$
So, $\Delta I_C=\alpha \times \Delta I_E$
$=0.98\times 2\times {10}^{-3}$
$=1.96$ mA

Now, $\Delta I_E=\Delta I_B+\Delta I_C$

$\Delta I_B=\Delta I_C-\Delta I_E$
$\Delta I_B=(2-1.96)$ mA
$=0.04$ mA