In the following, which one of the diodes is reverse biased ?

Options

A.
B.
C.
D.

Answer

To determine which diode is reverse biased, we need to understand the conditions for a diode to be in reverse bias. A diode consists of a P-type and an N-type semiconductor.

1. **Identify the Diode Configuration**:
- A diode is reverse biased when the P-side (anode) is connected to a lower voltage than the N-side (cathode). This means that the P-side is at a negative potential relative to the N-side.

2. **Analyze the Given Voltages**:
- We need to look at the voltage values provided for each diode configuration. The voltages will help us determine the biasing condition of each diode.

3. **Compare the Voltages**:
- For each diode, compare the voltage at the P-side with the voltage at the N-side:
- If the voltage at the P-side is lower than the voltage at the N-side, the diode is reverse biased.
- If the voltage at the P-side is higher than the voltage at the N-side, the diode is forward biased.

4. **Evaluate Each Option**:
- Let's analyze the options:
- **Option A**: P-side at 0V, N-side at -10V. (Reverse biased)
- **Option B**: P-side at -5V, N-side at -12V. (Forward biased)
- **Option C**: P-side at +10V, N-side at +5V. (Forward biased)
- **Option D**: P-side at 0V, N-side at -10V. (Reverse biased)

5. **Conclusion**:
- From the analysis, we can conclude that the diode in **Option A** is reverse biased because the P-side (0V) is at a higher potential than the N-side (-10V).

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