When n-p-n junction transistor is used as an amplifier in common emitter mode,
When n-p-n junction transistor is used as an amplifier in common emitter mode,
the input impedance is high and the output impedance is low.
the base emitter junction is reverse biased.
input signal is applied between the base and emitter and output is obtained between collector and emitter.
the input voltage and output voltage are in phase.
Solution
Common Emitter Configuration:
In this configuration, the emitter terminal is common to both the input and output sides of the circuit.
The input signal is applied across the base-emitter junction.
The output is taken across the collector-emitter junction.
Biasing:
For proper operation, the base-emitter junction should be forward-biased, not reverse-biased as mentioned in Option B. Therefore, Option B is incorrect.
Phase Relationship:
The output voltage is inverted with respect to the input voltage, meaning they are 180 degrees out of phase. Hence, Option D is incorrect.
Impedance Characteristics:
The input impedance is generally low to moderate, not high, and the output impedance is generally moderate to high. Thus, Option A is incorrect.
In summary, the common emitter configuration is widely used due to its ability to amplify the input signal with phase inversion, making Option C the accurate description.