Which of the following exhibit perfect diamagnetism?

Options

A. (a)Conductor
B. (b)Semiconductor
C. (c)Insulator
D. (d)Superconductor

Answer

To determine which of the following materials exhibit perfect diamagnetism, we need to analyze the properties of each option provided: conductor, semiconductor, insulator, and superconductor.

### Step-by-Step Solution:

1. **Understanding Diamagnetism**:
- Diamagnetism is a property of materials that causes them to create an opposing magnetic field when exposed to an external magnetic field. This results in the repulsion of the magnetic field lines.

2. **Analyzing Each Option**:
- **Conductor**: Conductors have free electrons that can move under the influence of an external magnetic field, leading to induced currents. This results in a magnetic field that can enhance the external field rather than repel it. Therefore, conductors do not exhibit perfect diamagnetism.

- **Semiconductor**: Semiconductors have a limited number of charge carriers. While they can exhibit some magnetic properties, they do not show perfect diamagnetism because they do not completely repel magnetic field lines.

- **Insulator**: Insulators do not have free charge carriers. They can exhibit weak diamagnetism, but they do not show perfect diamagnetism as they do not completely repel magnetic field lines.

- **Superconductor**: Superconductors are materials that exhibit perfect diamagnetism when cooled below a certain critical temperature. They expel all magnetic field lines from their interior, a phenomenon known as the Meissner effect. This means they perfectly repel magnetic fields.

3. **Conclusion**:
- Among the options provided, only superconductors exhibit perfect diamagnetism.

### Final Answer:
The material that exhibits perfect diamagnetism is **Superconductor**.

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