The susceptibility of a diamagnetic substance is

Options

A. `oo`
B. Zero
C. 1
D. `-1`

Answer

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

### Step-by-Step Solution:

1. **Understand the Definition of Susceptibility**:
- Susceptibility (χ) is a measure of how much a material will become magnetized in an applied magnetic field. It is defined as the ratio of the magnetization (M) of the material to the applied magnetic field strength (H).

2. **Know the Relationship with Relative Permeability**:
- The susceptibility is related to the relative permeability (μ_r) of the material by the formula:
\[ \chi = \mu_r - 1 \]

3. **Identify the Nature of Diamagnetic Substances**:
- Diamagnetic substances are characterized by having a relative permeability (μ_r) that is less than 1. This means that they are repelled by magnetic fields.

4. **Substitute the Value of μ_r for Diamagnetic Substances**:
- Since for diamagnetic materials, μ_r < 1, we can denote it as:
\[ \mu_r = 1 - k \quad \text{(where } k > 0\text{)} \]
- Thus, substituting this into the susceptibility formula gives:
\[ \chi = (1 - k) - 1 = -k \]

5. **Conclude the Value of Susceptibility**:
- Since k is a positive number, χ will be negative. Therefore, the susceptibility of a diamagnetic substance is negative.

6. **Select the Correct Option**:
- Given the options: 0, 1, -1, or infinity, the only negative value is -1. Thus, the correct answer is:
\[ \chi < 0 \quad \text{(specifically, it can be -1 or any negative value)} \]

### Final Answer:
The susceptibility of a diamagnetic substance is **negative**.

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