Question

The current gain ( $\beta$ ) of a transistor in common base mode is 40. To change the collector current by 160mA, the necessary change in the base current is (at constant V${}_{CE}$)

• A. 0.25$\mu$
• B. 4 $\mu$ A
• C. 4mA
• D. 40mA

Answer 1

The correct option is C 4mA

Given: Current gain, $\beta =40$

Change in collector current, $\Delta I_c=160mA$

Current gain, $\beta =\frac{\Delta I_c}{\Delta I_b}$

$40=\frac{160mA}{\Delta I_b}⟹\Delta I_b=4mA$

Thus, the change in the base current is equal to $4mA$.