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It
is the phenomenon in which a change of current in one coil causes an induced
emf in another coil placed near to the first coil. The coil in which current
is changed is called primary coil and the coil in which emf is induced is
called secondary coil.
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| EXPLANATION |
| Consider
two coils placed near each other as shown in figure. When current is passed
through the primary coil, magnetic flux is produced. This magnetic flux
is also linked with the secondary coil. If the current is changed by varying
the resistance in the primary circuit, the magnetic flux also change. As
this changing flux is linked with the secondary coil, it induces an emf
in it. This phenomenon of inducing emf in a coil by changing current in
another coil is known as mutual inductance. |
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MATHEMATICAL
REPRESENTATION
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| Emf
induced by mutual induction phenomenon is directly proportional to the change
of electric current in the primary coil. |
(emf)s a –DIp/Dt
(emf)s = -M DIp/Dt
where M = mutual inductance of two coils.
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| MUTUAL
INDUCTANCE |
| Mutual
inductance is defined as the ratio of emf induced in the secondary coil
to the rate of change of electric current in the primary coil. |
M = (emf)s/DIp/Dt
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Value of ‘M’ depends upon the number of turns of secondary coil, their
cross-sectional area and their closeness to each other.
Unit of mutual inductance is Henry. |
| HENRY |
The mutual inductance of two coils is one Henry if a current at the rate
of one ampere per second in the primary causes an induced emf of one volt
in the secondary. |
