If a p-n junction diode is reverse biased, then the resistance measured by an ohm-meter will be

Options

A. zero
B. low
C. high
D. infinite

Answer

To solve the question about the resistance measured by an ohm-meter when a p-n junction diode is reverse biased, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the p-n Junction Diode**:
- A p-n junction diode consists of two regions: the p-type (positive) and the n-type (negative). The p-type region contains holes (positive charge carriers), while the n-type region contains electrons (negative charge carriers).

2. **Reverse Bias Condition**:
- In reverse bias, the p-type side is connected to the negative terminal of the power supply, and the n-type side is connected to the positive terminal. This arrangement increases the potential barrier at the junction.

3. **Effect on Charge Carriers**:
- When reverse biased, the holes in the p-region are pulled away from the junction, and the electrons in the n-region are also pulled away. This movement increases the width of the depletion region (the area around the junction where there are no charge carriers).

4. **Increase in Potential Barrier**:
- As the depletion region widens, the potential barrier increases, making it difficult for charge carriers to cross the junction. This results in a significant increase in resistance.

5. **Current Flow**:
- Ideally, in reverse bias, the current that flows through the diode is nearly zero because the potential barrier is too high for charge carriers to overcome. In practical scenarios, there may be a very small leakage current, but it is still negligible compared to the forward bias condition.

6. **Resistance Measurement**:
- Given that the current is very low (close to zero), the resistance measured by an ohm-meter will be very high. In ideal conditions, we can consider this resistance to be infinite because no current flows.

### Conclusion:
- If a p-n junction diode is reverse biased, the resistance measured by an ohm-meter will be very high (practically infinite).