Question

The unit of magnetic dipole moment is

• A. A$.$m
• B. A m$^2$
• C. A/m$^2$
• D. m$^2$/A

Hint:

Remember \(\mu = I A\) (current \(\times\) area). Current is in amperes, area in m$^2$ \(⇒\) unit A\,m$^2$.

Answer 1

The Correct Option is B

For a current loop, the magnetic dipole moment is \[ \vec{\mu}= I\,\vec{A}, \] where \(I\) (ampere) is the current and \(\vec{A}\) (m$^2$) is the area vector. Hence the SI unit is A\,m$^2$.
Option (A) A$.$m corresponds to an obsolete pole–length model; (C) and (D) are dimensionally inconsistent with \(\mu=IA\).