The permeability of a specimen decreases drastically above certain temperature . The specimen could be

Options

A. a. Ferromagnetic
B. b. Diamagnetic
C. c. Paramagnetic
D. Non-magnetic

Answer

To solve the question regarding the permeability of a specimen that decreases drastically above a certain temperature, we will analyze the properties of different types of magnetic materials: ferromagnetic, paramagnetic, diamagnetic, and non-magnetic.

### Step-by-Step Solution:

1. **Understanding Magnetic Materials**:
- There are three main types of magnetic materials: ferromagnetic, paramagnetic, and diamagnetic. Each type has distinct behaviors in response to temperature changes.

2. **Graph of Susceptibility vs. Temperature**:
- The susceptibility (χ) of a material is related to its relative permeability (μr) by the equation:
\[ \chi = \mu_r - 1 \]
- This relationship implies that as susceptibility changes with temperature, so does permeability.

3. **Behavior of Ferromagnetic Materials**:
- Ferromagnetic materials exhibit a significant change in susceptibility at a specific temperature known as the Curie temperature (T_c). Below T_c, they are ferromagnetic, and their susceptibility is high. Above T_c, they transition to a paramagnetic state, where susceptibility decreases significantly.

4. **Graph Analysis**:
- The graph of susceptibility versus temperature for ferromagnetic materials shows a steep decline in susceptibility as the temperature exceeds T_c. This indicates a drastic decrease in permeability.

5. **Comparison with Other Materials**:
- **Diamagnetic Materials**: Their susceptibility is negative and does not depend significantly on temperature. Thus, they do not show a drastic change in permeability with temperature.
- **Paramagnetic Materials**: While they do have a positive susceptibility, their decrease in permeability with temperature is gradual, not drastic.
- **Non-Magnetic Materials**: These materials do not exhibit magnetic properties and thus do not show any relationship with temperature.

6. **Conclusion**:
- Given that the question specifies a drastic decrease in permeability above a certain temperature, the only suitable option is **ferromagnetic** materials, as they undergo a significant change in magnetic properties at the Curie temperature.

### Final Answer:
The specimen could be **ferromagnetic**.