Final answer:
In an RC coupled amplifier, the collector-base junction of each transistor is reverse biased. This ensures the transistor operates in the active region for amplification. The current gain of a transistor is the ratio of collector to base current.
Step-by-step explanation:
In an RC coupled amplifier circuit, the collector-base junction of each transistor becomes reverse biased. This configuration is crucial for the operation of the amplifier, ensuring that the transistor operates in the active region, where it can effectively amplify the input signal.
In the active region, the emitter-base junction is forward biased, which allows the base current to control the much larger collector current. As a result, even small changes in the base current can lead to significant changes in the collector current - a property that is essential for amplification purposes.
The current gain of a transistor is the ratio of the collector current to the base current, typically denoted by β or hFE. For example, if a transistor has a base current of 4.2 mA and a collector current of 3.4 A, the current gain would be 3.4 A / 4.2 mA, which equals 809.52.