Magnetic current, i m , is an alternate name for the time rate of change of flux, Φ Φ ˙ ˙ (SI unit : Wb /sec or volts), which is analogous to electrical current in an electric circuit. In the physical circuit, Φ Φ ˙ ˙ , is magnetic displacement current. The magnetic current flowing through an element of cross section, S , is the area integral of the magnetic flux density B .