Question

Define the term magnetic moment.

Answer 1

Magnetic moment is the property of a magnet that interacts with an applied field to give a mechanical moment. Recall the terms torque and the magnetic field. Magnetic moment is a vector quantity. It can be defined as in the relation, $\tau \, = \,m \times \,B$, Here, $\tau$ is torque, $m$ is magnetic moment and $B$ is external magnetic field.

Complete answer:
The magnetic moment of an object is a vector quantity, which describes the magnetic field created by that object. Magnetic moment is magnetic strength and orientation of a magnet or that object that produces a magnetic field.Magnetic moment can be produced by movement in charges (flow of current) or the spin angular momentum.

Magnetic moments can be measured by the instruments called magnetometers. A current carrying coil has two faces with two different poles. Magnetic moments can be shown by permanent magnets, electromagnets, current carrying loops, atoms and molecules and subatomic particles (due to spin magnetic moments). SI units of magnetic moments are $A{m^2}$ (having dimensional formula: $[{\text{I}}{{\text{L}}^2}]$ )

The relation between torque, magnetic moment and the magnetic field is
$\tau \, = \,m \times \,B$
The dipole moment of a magnet placed in a magnetic field is similar as dipole formation occurs in electrostatics. But in electrostatics monopoles can exist whereas in magnetostatics monopoles can’t exist.

Note: Magnitude of the magnetic moment is defined as the maximum torque experienced by the magnet when placed in a unit external magnetic field. When a magnet is placed in the external magnetic field then it tries to align it with the external magnetic field due to some torque experienced by the magnet, this is because of the magnetic dipole. This torque can be calculated by the formula $\tau \, = \,m \times \,B$ , where m is the magnetic moment.