For a diamagnetic substance, susceptibility is

Options

A. small and positive
B. small and negative
C. large and positive
D. large and negative

Answer

To determine the susceptibility of a diamagnetic substance, we can follow these steps:

### 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 indicates the degree of magnetization of a substance in response to an external magnetic field.

2. **Characteristics of Diamagnetic Substances**:
- Diamagnetic substances are materials that create an opposing magnetic field when subjected to an external magnetic field. This results in a very weak repulsion from the magnetic field.

3. **Expression for Permeability**:
- The permeability (μ) of a material can be expressed in terms of the permeability of free space (μ₀) and the relative permeability (μᵣ):
\[ \mu = \mu_0 (1 + \chi) \]
- Here, μ₀ is the permeability of free space, and χ is the susceptibility.

4. **Behavior of Diamagnetic Materials**:
- For diamagnetic materials, the susceptibility (χ) is negative. This means that when we substitute χ into the equation, we will have:
\[ \chi < 0 \]

5. **Conclusion on Susceptibility**:
- Since the susceptibility of diamagnetic substances is negative, we can conclude that:
\[ \chi \leq 0 \]
- This indicates that the susceptibility of diamagnetic substances is small and negative.

### Final Answer:
The susceptibility of a diamagnetic substance is less than or equal to zero (χ ≤ 0).

---