Question

The power gain for common base amplifier is 800 and the voltage amplification factor is 840. The collector current when base current is $1.2mA$ is

• A. 24 mA
• B. 12 Ma
• C. 6 m A
• D. 3 mA

Answer 1

Answer: (A)

24 mA

Answer 2

: current gain,

$\alpha = \frac{Powergain}{Voltagegain} = \frac{800}{840} = \frac{20}{21}$

Now, $\beta = \frac{\alpha}{1 - \alpha} = \frac{(20/21)}{1 - (20/21)} = 20$

As, $\beta = \frac{I_{C}}{I_{B}}$

$\therefore I_{C} = \beta I_{B} = 20 \times 1.2 = 24mA$ (Given $I_{B} = 12mA$)