Question

Define the magnetic moment of a current-carrying coil. Write its SI unit.

Hint:

The magnetic moment is a vector quantity, pointing normal to the plane of the coil, and it depends on both the current and the area of the coil.

Answer 1

The magnetic moment \( \vec{m} \) of a current-carrying coil is defined as the product of the current \( I \) flowing through the coil and the area \( A \) of the coil. Mathematically, it is given by: \[ \vec{m} = I \cdot A \cdot \hat{n} \] where: - \( I \) is the current in amperes (A),
- \( A \) is the area of the coil in square meters (\( \text{m}^2 \)),
- \( \hat{n} \) is the unit vector normal to the plane of the coil, indicating the direction of the magnetic moment.
The SI unit of magnetic moment is \( \text{A} \cdot \text{m}^2 \) (ampere-square meter).