Which of the following is not transducer?

Options

A. Loudspeaker
B. Amplifier
C. Microphone
D. All of these

Explanation

To determine which of the following is not a transducer, we need to understand the definition of a transducer and analyze each option provided.

### Step-by-Step Solution:

1. **Understand the Definition of a Transducer**:
- A transducer is a device that converts one form of energy into another. For example, it can convert sound energy into electrical energy or vice versa.

2. **Analyze Each Option**:
- **Option A: Loudspeaker**:
- A loudspeaker converts electrical energy into sound energy. Therefore, it is a transducer.
- **Option B: Amplifier**:
- An amplifier increases the intensity of a signal but does not convert energy from one form to another. It simply boosts the existing signal. Therefore, it is not a transducer.
- **Option C: Microphone**:
- A microphone converts sound energy into electrical energy. Hence, it is a transducer.

3. **Conclusion**:
- From the analysis, the only device that does not convert energy from one form to another is the amplifier. Therefore, the correct answer is **Option B: Amplifier**.

### Final Answer:
**B: Amplifier**

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