Consider the following statements and identify the correct answer. a) In forward bias of p-n diode, the effective barrier potential is `(V_B -V). (V_B` is barrier potential and V is the applied external voltage) b) In reverse bias of p-n diode, the effective barrier potential is` (V_B +V) `c) In forward bias, an ideal p-n diode offers zero resistance d) In reverse bias, an ideal p-n diode offers infinite resistance

Options

A. a, b only are true
B. a, b, c only are true
C. a, b, c, d are true
D. all are false

Answer

To solve the question, we will analyze each statement regarding the behavior of a p-n diode under forward and reverse bias conditions.

### Step-by-Step Solution:

1. **Understanding Forward Bias**:
- In forward bias, the p-side (anode) of the diode is connected to the positive terminal of the battery, and the n-side (cathode) is connected to the negative terminal.
- The applied external voltage (V) opposes the built-in potential (V_B) of the diode. Therefore, the effective barrier potential becomes:
\[ \text{Effective Barrier Potential} = V_B - V \]
- **Conclusion**: Statement (a) is correct.

2. **Understanding Reverse Bias**:
- In reverse bias, the p-side is connected to the negative terminal and the n-side is connected to the positive terminal.
- The applied external voltage (V) adds to the built-in potential (V_B), increasing the effective barrier potential:
\[ \text{Effective Barrier Potential} = V_B + V \]
- **Conclusion**: Statement (b) is correct.

3. **Resistance in Forward Bias**:
- In forward bias, the depletion region narrows, allowing current to flow easily. For an ideal p-n diode, this means it can be treated as having zero resistance.
- **Conclusion**: Statement (c) is correct.

4. **Resistance in Reverse Bias**:
- In reverse bias, the depletion region widens significantly, preventing current flow. An ideal p-n diode in reverse bias can be considered to have infinite resistance.
- **Conclusion**: Statement (d) is correct.

### Final Conclusion:
All statements (a), (b), (c), and (d) are correct. Therefore, the correct answer is that all statements are true.