The permanent magnetic moment of the atoms of a material is zero. The material

Options

A. must be paramagnetic
B. must be diamagnetic
C. must be ferromagnetic
D. may be paramagnetic

Answer

To determine the type of material whose permanent magnetic moment is zero, we can analyze the properties of different types of magnetic materials. Here’s a step-by-step solution:

### Step 1: Understand Magnetic Moments
Magnetic moment is a vector quantity that represents the magnetic strength and orientation of a magnet or current-carrying loop. It can be permanent (inherent) or induced by an external magnetic field.

**Hint:** Remember that materials can be classified based on their magnetic properties: diamagnetic, paramagnetic, and ferromagnetic.

### Step 2: Classify Magnetic Materials
1. **Diamagnetic Materials**: These materials have no permanent magnetic moment. When an external magnetic field is applied, they develop a very weak magnetic moment in the opposite direction, which disappears when the external field is removed.

2. **Paramagnetic Materials**: These materials have a small, positive magnetic moment due to unpaired electrons. They align with an external magnetic field, but this alignment is lost when the field is removed.

3. **Ferromagnetic Materials**: These materials have a strong permanent magnetic moment due to aligned magnetic domains. They retain their magnetic properties even when the external field is removed.

**Hint:** Focus on the characteristics of diamagnetic materials, as they are the only type that has no permanent magnetic moment.

### Step 3: Analyze the Given Condition
The question specifies that the permanent magnetic moment of the atoms of a material is zero. This means that when the external magnetic field is switched off, the material should not exhibit any net magnetic moment.

**Hint:** Consider how each type of material behaves when the external magnetic field is removed.

### Step 4: Conclusion
Based on the analysis:
- **Diamagnetic materials** have a permanent magnetic moment of zero.
- **Paramagnetic materials** have a non-zero magnetic moment that does not retain after the field is removed.
- **Ferromagnetic materials** have a strong permanent magnetic moment that persists even without an external field.

Thus, the material in question is **diamagnetic**.

**Final Answer:** The material is **diamagnetic**.