The process in which a changing current in one coil induces emf in another coil, is called mutual induction.While the phenomenon in which a changing current in a coil induces an emf in itself is called self-induction.
What is Mutual induction?
“The process of inducing e.m.f in the secondary coil by changing the magnetic flux of the primary coil with the help of varying current through it is called mutual induction.”
If two coils placed together, then changing the current in one coil sets up a changing magnetic field in the other coil, so induced an e.m.f in the other coil.
Consider two coils located near each other. The coil with the battery circuit is called the primary coil and the coil joined with the galvanometer circuit is called the secondary coil. The secondary coil within the magnetic field of the current-carrying primary coil. The current in the primary coil can be changed by a rheostat.
If the current is changed in the primary coil , the magnetic flux through the secondary coil due to primary also changes. So, an emf will be induced in the secondary coil also.
Derivation of mutual induction:
“The process of inducing emf in the coil due to the change of current in the coil itself is called self-induction.”
The change in the magnetic flux in a coil may be due to the relative motion of the coil and the magnetic field or due to the change of current in the coil itself.
Let us consider a coil of n turns with a battery, a galvanometer and a rheostat in its circuit. If the current in the coil is changed with the help of rheostat, then change of magnetic flux also be felt in the coil itself, therefore inducing an e.m.f in coil is:
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