related to the flux change? . The motional emf discussed in Section . can be argued independently from Faraday’s law using the Lorentz force on moving charges.
However, Quantity Symbol Units Dimensions Equations Magnetic Flux Φ B Wb (weber) [M L T – A – ] Φ B = B A i EMF V (volt) [M L T – A – ] ε = B d( )/d N Φ Mutual Inductance M H (henry) [M L T – A – ] ε ( /d M I = − Self Inductance L H (henry) [M L T – A – ] ( d /d L I ε = − . A changing current in a coil (coil ) can induce an emf in a nearby coil (coil ). This relation is given by, I M ε = − The quantity M is called mutual inductance of coil with respect to coil . One can similarly define M .
There exists a general equality, M = M . When a current in a coil changes, it induces a back emf in the same coil. The self-induced emf is given by, I L ε = − L is the self-inductance of the coil. It is a measure of the inertia of the coil against the change of current through it.
. The self-inductance of a long solenoid, the core of which consists of a magnetic material of permeability μ r , is given by L = μ r μ n Al where A is the area of cross-section of the solenoid, l its length and n the number of turns per unit length. . In an ac generator, mechanical energy is converted to electrical energy by virtue of electromagnetic induction.
If coil of N turn and area A is rotated at ν revolutions per second in a uniform magnetic field B, then the motional emf produced is ε = NBA ( πν ) sin ( πν t ) where we have assumed that at time t = s,