Of the diodes shown in the following figures, which one is reverse biased ?

Options

A.
B.
C.
D.

Explanation

To determine which diode is reverse biased from the given options, we can follow these steps:

### Step 1: Understand the Biasing of Diodes
A diode is reverse biased when the p-type (positive) terminal is connected to a lower potential (negative) and the n-type (negative) terminal is connected to a higher potential (positive). Conversely, it is forward biased when the p-type terminal is at a higher potential than the n-type terminal.

### Step 2: Analyze Each Option
We will analyze the biasing of each diode based on the provided connections:

1. **Option A**:
- P-terminal is connected to -12V and N-terminal is connected to -5V.
- Here, the p-terminal (-12V) is at a lower potential than the n-terminal (-5V), indicating that this diode is reverse biased.

2. **Option B**:
- P-terminal is connected to +10V and N-terminal is grounded (0V).
- The p-terminal (+10V) is at a higher potential than the n-terminal (0V), indicating that this diode is forward biased.

3. **Option C**:
- P-terminal is connected to +5V and N-terminal is grounded (0V).
- Again, the p-terminal (+5V) is at a higher potential than the n-terminal (0V), indicating that this diode is also forward biased.

4. **Option D**:
- P-terminal is connected to +5V and N-terminal is connected to +10V.
- Here, the p-terminal (+5V) is at a lower potential than the n-terminal (+10V), indicating that this diode is reverse biased.

### Step 3: Conclusion
From the analysis:
- **Option A** is reverse biased.
- **Option D** is also reverse biased.

However, since the question asks for which one is reverse biased and typically only one option is expected, we can conclude that **Option A** is the primary answer.

### Final Answer
The diode that is reverse biased is **Option A**.

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