In a common emitter amplifier circuit using an n-p-n transistor, the phase difference between the input and the output voltages will be:-

Options

A. Option1 180
B. Option2 45 degree
C. Option3 90 degree
D. Option4 135 degree

Answer

To determine the phase difference between the input and output voltages in a common emitter amplifier circuit using an NPN transistor, 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 between the base and the emitter, while the output is taken from the collector with respect to the emitter.

2. **Signal Inversion**:
- The common emitter configuration is known for its ability to invert the input signal. This means that when the input voltage increases, the output voltage decreases, and vice versa.

3. **Phase Relationship**:
- Since the output voltage is inverted relative to the input voltage, there is a phase shift of 180 degrees. This can be visualized as follows:
- If the input waveform is a sine wave, the output waveform will be a sine wave that is flipped upside down.

4. **Conclusion**:
- Therefore, the phase difference between the input and output voltages in a common emitter amplifier circuit using an NPN transistor is 180 degrees.

### Final Answer:
The phase difference between the input and the output voltages will be **180 degrees**.

---