Question

If number of turn, area and current through it is given by n, A and i respectively then its magnetic moment will be : - 

• A. niA
• B. n² iA
• C. niA²
• D. \(\frac{ni}{\sqrt A}\)

Answer 1

The Correct Option is A

To solve this problem, we need to understand the concept of the magnetic moment of a coil. The magnetic moment (\(M\)) of a coil carrying current is given by the formula:

M = n \cdot i \cdot A

where:

• n is the number of turns in the coil,
• i is the current flowing through the coil,
• A is the area of the coil.

Given the options:

1. niA
2. n^2 iA
3. niA^2
4. \(\frac{ni}{\sqrt A}\)

The correct formula for magnetic moment is the product of the number of turns, the current, and the area, which matches the first option: niA.

Let's rule out the other options:

• n^2 iA: This option incorrectly squares the number of turns, which is not part of the standard formula.
• niA^2: This option incorrectly squares the area, which does not match the standard formula.
• \(\frac{ni}{\sqrt A}\): This option introduces a division by the square root of the area, which is not part of the standard calculation.

Thus, the correct answer is indeed niA, as it directly correlates with the formula for the magnetic moment of a coil.