A `p-n` junction diode is reverse biased. Then

Options

A. no current flows
B. the depletion region is increased
C. the depletion region is reduced
D. the height of the potential barrier is reduced

Explanation

To solve the question regarding the behavior of a reverse-biased p-n junction diode, we can break it down into a series of logical steps:

### Step-by-Step Solution:

1. **Understanding Reverse Bias**: When a p-n junction diode is reverse biased, the positive terminal of the battery is connected to the n-type material, and the negative terminal is connected to the p-type material. This arrangement creates a potential barrier that opposes the flow of charge carriers.

2. **Effect on Charge Carriers**: In reverse bias, the holes in the p-type region are attracted towards the negative terminal of the battery, while the electrons in the n-type region are attracted towards the positive terminal. This movement of charge carriers increases the width of the depletion region.

3. **Depletion Region**: The depletion region is the area around the p-n junction where there are no free charge carriers (holes or electrons). As the holes and electrons are pulled away from the junction, the depletion region widens.

4. **Current Flow**: Due to the widening of the depletion region, the diode effectively behaves like an open circuit. This means that under normal reverse bias conditions, there is no significant current flow through the diode, except for a very small leakage current that may occur due to minority charge carriers.

5. **Conclusion**: The correct conclusion is that when a p-n junction diode is reverse biased, the depletion layer increases, and it acts like an open circuit, blocking any significant current flow.

### Final Answer:
The correct option is **B**: The depletion layer increases, and the diode behaves like an open circuit, blocking any current flow.

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