Basic laws of magnetic circuits

Faraday law
The voltage on the coil is equal to the algebraic sum of the voltage drops on the resistance of the winding wire and the self-induced EMF


Total current law
The circulation of the magnetic field H along any closed loop is equal to the sum of the electrical currents of the wires.


J-current density

Mdc along a closed loop, l is equal to the total current In penetrating the surface bounded by the given circuit:


Magnetic circuit - a system of series-connected ferromagnetic and other elements through which the magnetic flux closes.
The average length of the magnetic circuit:


Air gap coil layout


magnetic field strength


Ohm's law for a magnetic circuit


Reluctance


Magnetic induction
Equation for closed loop magnetic induction sources


In free space


For ferromagnets