# Electric and magnetic SI units

Analogies can be found between the electrical circuit and the magnetic circuit. According to the ohmic resistance, a magnetic resistance is therefore defined in a magnetic circuit. In an electrical circuit the voltage is the reason for the electric current. The magnetic field of an electromagnet is induced by the magnetomotive force of an operating coil. Thus, the magnetomotive force corresponds to the magnetic voltage.

Symbol Name of Quantity Derived Units Unit Equation
U Voltage Volt V
Q Magnetomotive force Ampere A Q = I * N
I Electric current Ampere A
F Magnetic flux Weber Wb (Vs)
J Electric current density Ampere/Square meter A/m2
B Magnetic field density Tesla T B = F / A
s Electrical conductivity Siemens / Meter S/m
µ Permeability Henry/Meter H/m µ = µ0 * µr
R Electrical resistance Ohm 1Ú2
Rm Electrical resistance Ampere/Weber A/Wb Rm = l/(µ*A)
G electrical conductance Siemens S G = 1 / R
L Magnetic permeance Weber/Ampere Wb/A L = 1 / Rm
Ohm’s Law U = I * R Q = F * Rm
L Inductance Henry H