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Question: The current gain for a common emitter amplifier is 69 if the emitter current is 7 mA, the base curre...

The current gain for a common emitter amplifier is 69 if the emitter current is 7 mA, the base current is

A

0.1mA0.1mA

B

1 mA

C

0.2mA0.2mA

D

2 mA

Answer

0.1mA0.1mA

Explanation

Solution

: current gain, β=ICIB\beta = \frac{I_{C}}{I_{B}}

For common emitter configuration

IE=ICI_{E} = I_{C}

IC=7mA\therefore I_{C} = 7mA

IB=ICβ=7×103A69=0.1mA\therefore I_{B} = \frac{I_{C}}{\beta} = \frac{7 \times 10^{- 3}A}{69} = 0.1mA