Magnetomotive force

The magnetic voltage or magnetic source voltage (symbol: V m or order ) is a term used in electrical term. The magnetic voltage measures the exciting force of the magnetic field strength. It is the path integral over the magnetic field strength. In the case of a closed path ( orbit ) is called the magnetic potential Θ. It is equal to that enclosed by this round, including current displacement current.

The magnetic potential is physically not the same as the electrical voltage. The choice of terminology refers to the formal analogy with respect to the magnetic vector potential of the field theory.


The unit of magnetic tension in the SI is the ampere. Previously, the amps when specifying by floods was as ampere ( unit symbol: Aw, AW ), since the same current circulation several times " by wind " can.

In the CGS system of units, the unit Gilbert ( unit symbol: Gi) is the flux used.

Ampere's law

The Ampere's law describes the relationship between the magnetic flux and the enclosed current.

Hopkinsonsches law

With the magnetic flux Φ and the magnetic resistance Rm is the magnetic voltage Vm depends on the law hopkinsonsche

Together. This law is the magnetic equivalent to Ohm's law for electrical circuits. In contrast to the electrical circuit ( in the absence of variable magnetic fields) is the sum of all voltages in a loop circulation but not zero, but the magnetic flux.

Magnetic voltage by a line manager

To a straight line electrical conductors, one imagines level subjects. You can specify the magnetic voltage depends on the angle between two surfaces in this case:

For the magnetic field strength H is the valid

Where ds is a segment of the field length L of the magnetic field strength and with r the radius of the circle around the current I to which the field is measured. In this formula, Vm is equivalent to θ.

Magnetic flux of a coil

In the case of a long and thin cylinder with a coil number of turns N, to be traversed by a current I, to a good approximation the following applies: