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

Options

A. resistivity
B. conductivity
C. resistance
D. conductance

Answer

To solve the question of which substances have a positive permeability and a negative magnetic susceptibility, we need to understand the definitions and properties of magnetic susceptibility and permeability for different materials.

### Step-by-Step Solution:

1. **Understand Magnetic Susceptibility (χ)**:
- Magnetic susceptibility 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 (paramagnetic materials).
- **Negative susceptibility** indicates that the material is repelled by the magnetic field (diamagnetic materials).

2. **Understand Permeability (μ)**:
- Permeability is a measure of how easily a magnetic field can penetrate a material.
- It is defined as:
\[ \mu = \mu_0 \cdot \mu_r \]
where:
- \(\mu_0\) is the permeability of free space (a positive constant).
- \(\mu_r\) is the relative permeability of the material.
- For most materials, permeability is positive.

3. **Analyze the Given Options**:
- **Option 1: Paramagnetic Material**:
- Paramagnetic materials have positive susceptibility (χ > 0) and positive permeability (μ > 0).
- This option is incorrect.

- **Option 2: Diamagnetic Material**:
- Diamagnetic materials have negative susceptibility (χ < 0) and positive permeability (μ > 0).
- This option is correct.

- **Option 3: Paramagnetic Material (again)**:
- Same as option 1, this is incorrect for the same reasons.

- **Option 4: Superconductor**:
- Superconductors exhibit perfect diamagnetism (χ = -1) and have positive permeability. However, not all superconductors behave the same way, and some may not fit the criteria.
- This option is also not a definitive answer.

4. **Conclusion**:
- The only substance from the options provided that has a positive permeability and a negative magnetic susceptibility is **Option 2: Diamagnetic Material**.

### Final Answer:
**Diamagnetic Material** has positive permeability and negative magnetic susceptibility.