Magnetic field created by a current ( magnetomotive force.F=N*I)


An electromagnet is a type of magnet in which the magnetic field is produced by electric current. The magnetic field disappears when the current is turned off. Electromagnets usually consist of a large number of closely spaced turns of wire that create the magnetic field. The wire turns are often wound around a magnetic core made from a ferromagnetic or ferrimagnetic material such as iron; the magnetic core concentrates the magnetic flux and makes a more powerful magnet. The magnetic field created by an electromagnet is proportional to both the number of turns in the winding “N” and the current in the wire, “I”, hence this product, NI, in ampere-turns, is given the name magnetomotive force. For an electromagnet with a single magnetic circuit, of which length Lcore of the magnetic field path is in the core material and length Lgap is in air gaps, the product NI is depended on the magnetic field and the length of the magnetic field path in the core material and in air gaps.

Related formulas


NThe number of turns (dimensionless)
IThe current in the wire (A)
BMagnetic field (T)
LcoreThe length of the magnetic field path (m)
μThe magnetic permeability of the core material at the particular B field used (N/A2)
LgapThe length of the magnetic field path in air gaps (m)
μ0magnetic constant