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Magnetic dipole moment
Intermediate
Current loop acts as a tiny magnet.
m = NIAA current loop has magnetic moment m = NIA (direction by right-hand rule). In a field it feels torque m × B and has energy −m·B.
N = 10, I = 2 A, A = 0.01 m²: 0.2 A·m².
Atoms and electrons also have magnetic moments.
In more detail
A current loop has a magnetic dipole moment μ = IA, pointing along its normal. Permanent magnets and atoms also have dipole moments, which determine their interaction with fields.
Real-world uses
- Atomic magnetic moments explain paramagnetism and ferromagnetism.
- Electric motors align dipoles to produce torque.
- A current loop behaves like a tiny bar magnet, which explains why loops and atoms interact with magnetic fields.
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Frequently asked questions
What units are used?
Ampere square metres.
Does a dipole produce a field?
Yes, its far field resembles that of a bar magnet.
How is the dipole moment found?
Multiply the number of turns, the current and the area of the loop.
Related topics in Magnetism & Induction
Toroid · Ampere's law · Helmholtz coils · Magnetic materials · Ferromagnetism and domains · Hysteresis