Which of the following arrangements shows the schematic alignment of magnetic moments of anti - ferromagnetic substance?

Options

A.
B.
C.
D.

Answer

To determine the schematic alignment of magnetic moments in an anti-ferromagnetic substance, we need to understand the key characteristics of anti-ferromagnetism. Here’s a step-by-step breakdown of the solution:

### Step 1: Understanding Anti-Ferromagnetism
Anti-ferromagnetic substances have magnetic moments that are aligned in opposite directions. This means that for every magnetic moment pointing in one direction, there is another magnetic moment pointing in the opposite direction.

**Hint:** Remember that in anti-ferromagnetic materials, the opposing magnetic moments cancel each other out.

### Step 2: Analyzing the Options
We will evaluate each of the given options to see which one accurately represents the anti-ferromagnetic alignment.

- **Option 1:** All domains are parallel to each other.
- This arrangement does not represent anti-ferromagnetism, as the moments would not cancel out.

**Hint:** Look for arrangements where moments oppose each other.

- **Option 2:** All domains are oriented downward.
- Similar to Option 1, this does not show any opposing moments, thus not representing anti-ferromagnetism.

**Hint:** Check for opposing orientations in the arrangement.

- **Option 3:** Two parallel moments, then anti-parallel, then parallel, then anti-parallel.
- This arrangement has unequal amounts of parallel and anti-parallel moments. The presence of parallel moments means they cannot cancel out completely.

**Hint:** Ensure that the arrangement shows equal opposing moments.

- **Option 4:** The first and second domains are oppositely oriented, and this pattern continues.
- In this arrangement, each pair of moments cancels each other out, leading to a net magnetic moment of zero.

**Hint:** Look for a consistent pattern of opposing moments that leads to cancellation.

### Step 3: Conclusion
After evaluating all the options, we find that **Option 4** is the correct arrangement that shows the schematic alignment of magnetic moments in an anti-ferromagnetic substance. In this option, the magnetic moments are aligned in such a way that they cancel each other out, resulting in a net magnetic moment of zero.

**Final Answer:** Option 4 is correct.