In a common emitter amplifier , the phase difference between the input signal voltage and output voltage is

Options

A. `(pi)/(4)`
B. 0
C. `pi`
D. `(pi)/(4)`

Answer

To determine the phase difference between the input signal voltage and output voltage in a common emitter amplifier, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Common Emitter Configuration**:
- In a common emitter amplifier, the input signal is applied to the base terminal of the transistor, and the output is taken from the collector terminal.

2. **Analyzing the Input and Output Signals**:
- The input signal voltage (Vin) is applied to the base, and the output voltage (Vout) is measured at the collector.

3. **Phase Relationship**:
- In a common emitter amplifier, when the input signal voltage increases, the output voltage decreases. This is due to the transistor operation, where an increase in base current leads to a decrease in collector current, resulting in a drop in the collector voltage.

4. **Determining the Phase Difference**:
- Since the input and output signals move in opposite directions (when one is positive, the other is negative), there is a phase difference of π radians (or 180 degrees) between them.

5. **Conclusion**:
- Therefore, the phase difference between the input signal voltage and the output voltage in a common emitter amplifier is π radians.

### Final Answer:
The phase difference between the input signal voltage and output voltage in a common emitter amplifier is **π radians** (or 180 degrees).