A magnetic circuit is composed of a magnetic core excited by a source of magnetic energy.
- turns of wire carrying a current are wrapped around one leg of the core.
- A magnetic field will be developed by the coil (solenoid) that acts as a source of magnetic energy.
- This is source of magnetic energy establishes a magnetic flux in the core, which flows around the magnetic circuit – this is called Magnetomotive Force (MMF).
- This is analogous to the way that Electromotive Force (EMF) excites electrons and makes them move around a closed path in an electric circuit.
The core is typically made of a ferromagnetic material (retain magnetic properties even after the external field is removed), so all lines of magnetic force will theoretically be confined within the magnetic core. This is because the the reluctance and resistance exhibited by the material in magnetic/electric circuits against the flow of magnetic flux/electric current is much smaller than those of the air; thus the magnetic flux/electric current will always choose the easier path to flow through.