Which of the following circuits provides full wave rectification of an ac input?

Options

A.
B.
C.
D.

Answer

To determine which circuit provides full wave rectification of an AC input, we need to analyze the behavior of diodes in the given circuits during both the positive and negative cycles of the AC waveform.

### Step-by-Step Solution:

1. **Understanding AC Input**:
- AC (Alternating Current) input alternates between positive and negative cycles. In a positive cycle, the voltage is positive, and in a negative cycle, the voltage is negative.

2. **Analyzing Each Option**:
- **Option A**:
- In this circuit, when the input is positive, one diode is forward-biased, allowing current to flow. However, during the negative cycle, both diodes become reverse-biased, and no current flows. Thus, this circuit does not provide full wave rectification.
- **Option B**:
- Similar to Option A, during the positive cycle, current flows through one diode. During the negative cycle, the other diode is reverse-biased, leading to no current flow. Therefore, this option also does not provide full wave rectification.
- **Option C**:
- In this circuit, during the positive cycle, one diode conducts, and during the negative cycle, the other diode conducts. However, both diodes cannot conduct simultaneously, and the output does not provide a full wave rectification.
- **Option D**:
- In this circuit, during the positive half cycle, one diode conducts, allowing current to flow. In the negative half cycle, the other diode conducts, allowing current to flow in the opposite direction. This results in a continuous output waveform that is always positive, thus providing full wave rectification.

3. **Conclusion**:
- After analyzing all options, **Option D** is the correct answer as it provides full wave rectification of the AC input.

### Final Answer:
**Option D** provides full wave rectification of an AC input.