In a p- n junction diode not connected to any circuit,

Options

A. the potential is the same everwhere
B. the p- type side is at a bigher potential that the n - type side
C. then is an electric at the junction directed from
D. there is an electric fied at the junction directed from the p- type side to the n - type side

Explanation

### Step-by-Step Solution:

1. **Understanding the Structure of a p-n Junction Diode**:
- A p-n junction diode consists of two semiconductor materials: p-type (which has an abundance of holes) and n-type (which has an abundance of electrons).

2. **Formation of the Depletion Layer**:
- When the p-n junction is formed, electrons from the n-side and holes from the p-side recombine at the junction. This recombination leads to the formation of a depletion layer, which is a region devoid of free charge carriers (holes and electrons).

3. **Creation of Electric Field**:
- The movement of holes towards the n-side and electrons towards the p-side creates an electric field across the depletion layer. The electric field direction is from the n-side (where the positive charge is due to the presence of holes) to the p-side (where the negative charge is due to the presence of electrons).

4. **Potential Difference**:
- Due to the electric field, there is a potential difference created across the junction. The p-side is at a higher potential compared to the n-side. This means that the potential is not uniform across the diode; it varies from high on the p-side to low on the n-side.

5. **Direction of Charge Carrier Movement**:
- The holes will move towards the n-side in the direction of the electric field, while the electrons will move towards the p-side against the direction of the electric field.

6. **Conclusion**:
- In a p-n junction diode that is not connected to any circuit, a depletion layer forms, an electric field is established, and there is a potential difference between the p-side and n-side, with the p-side being at a higher potential.

### Final Answer:
In a p-n junction diode not connected to any circuit, a depletion layer is formed, an electric field is created directed from the n-side to the p-side, and there is a potential difference with the p-side at a higher potential than the n-side.

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