which of the following substances have a positive permeability and a negative magnetic susceptibility

Options

A. ferromagnetic
B. paramagnetic
C. diamagnetic
D. non of these

Answer

To determine which substances have a positive permeability and a negative magnetic susceptibility, we need to understand the definitions and properties of the different types of magnetic materials: ferromagnetic, paramagnetic, and diamagnetic.

### Step-by-Step Solution:

1. **Understanding Magnetic Susceptibility**:
- Magnetic susceptibility (χ) is a measure of how much a material will become magnetized in an applied magnetic field.
- It can be positive or negative:
- **Positive susceptibility**: Indicates that the material is attracted to the magnetic field (ferromagnetic and paramagnetic materials).
- **Negative susceptibility**: Indicates that the material is repelled by the magnetic field (diamagnetic materials).

2. **Understanding Permeability**:
- Permeability (μ) is the measure of how easily a magnetic field can penetrate a material.
- It is always positive for all materials, but its value can vary significantly depending on the type of material.

3. **Analyzing the Given Options**:
- **Ferromagnetic Materials**:
- Have positive permeability and positive magnetic susceptibility. They are strongly attracted to magnetic fields.
- **Paramagnetic Materials**:
- Have positive permeability and positive magnetic susceptibility. They are weakly attracted to magnetic fields.
- **Diamagnetic Materials**:
- Have positive permeability but negative magnetic susceptibility. They are weakly repelled by magnetic fields.
- **None of These**:
- This option is irrelevant since we are looking for a specific type of material.

4. **Conclusion**:
- The only type of material that has a positive permeability and a negative magnetic susceptibility is **Diamagnetic Materials**.

Thus, the answer to the question is **Diamagnetic**.