In a `PN` -junction diode

Options

A. High potential at N side and low potential at P side
B. High potential at P side and low potential at N side
C. P and N both are at same potential
D. Undetermined

Explanation

To solve the question regarding the potential difference in a PN-junction diode, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the PN-Junction Diode**:
- A PN-junction diode consists of two regions: the P-type (positive) and the N-type (negative). The P-type region has an abundance of holes (positive charge carriers), while the N-type region has an abundance of electrons (negative charge carriers).

2. **Analyzing the Potential**:
- In a PN-junction diode, the P-side is typically at a higher potential compared to the N-side. This is due to the difference in charge carriers and the built-in electric field that forms at the junction when the diode is formed.

3. **Identifying the Potential Levels**:
- At the P-side, the potential is higher because it has more positive charge carriers (holes).
- At the N-side, the potential is lower due to the presence of more negative charge carriers (electrons).

4. **Evaluating the Options**:
- Given the options:
1. High potential at N side and low potential at P side
2. High potential at P side and low potential at N side
3. P and N both are at the same potential
4. Undetermined
- From our analysis, we can conclude that the correct option is:
- **High potential at P side and low potential at N side (Option 2)**.

### Final Answer:
The correct option is: **High potential at P side and low potential at N side**.