In transistor amplifier, base emitter junction is forward biased and collector base junction is reversed biased. The current gain is

Step-by-step solution

In a standard transistor amplifier (common-emitter configuration), the input signal is applied to the base terminal and the output is taken from the collector terminal. The AC current gain ( ) is defined as the ratio of the change in output current (collector current, I_C ) to the change in input current (base current, I_B ) at a constant collector-emitter voltage. = I_C I_B