Definition of Mutually Induced EMF
Definition: The electromotive force (EMF) induced in a coil due to the change in magnetic flux produced by a neighboring coil linked to it is termed mutually induced EMF. To understand this phenomenon, consider the following example:
Take coil AB where coil B, having N2 turns, is placed in close proximity to coil A with N1 turns, as illustrated in the figure below:
Mutually Induced EMF Explanation
When switch (S) in the circuit is closed, current I1 flows through coil A, generating magnetic flux ϕ1. Most of this flux, denoted ϕ12, couples with adjacent coil B.Adjusting variable resistor R changes the current in coil A, altering the flux linked to coil B and inducing an EMF. This induced EMF is termed mutually induced EMF.The induced EMF direction follows Lenz’s Law, opposing the current change in coil A that caused it. A galvanometer (G) connected to coil B measures this EMF.The rate of flux change in coil B depends on the rate of current change in coil A, highlighting the mutual inductance relationship between the coils.
The magnitude of the mutually induced emf is directly proportional to the rate of change of current in coil A.The proportionality constant M is termed mutual inductance (or the coefficient of mutual inductance), which quantifies the magnetic coupling strength between the coils.
