CBSE Class 12-science Answered
When a current is established in a conductor, a magnetic field is produced in its vicinity. We can visualize this field in terms of magnetic flux. If steady current flows the number of lines of force at a given place would remain the same. But if the current changes with time, the flux associated with the loop changes and hence an e.m.f is induced in the loop. This phenomenon is called as self induction.
Self-induction is the property of a coil, which enables the induction of an EMF in it when the current in the coil changes.
Consider a coil carrying a current I having N turns and lets the magnetic flux f be linked with the coil. If the current in the coil is changed, the flux link also changes. Thus, according to Faraday's law of electromagnetic induction, induces an EMF on to itself. This EMF is called self-induced EMF and this phenomenon is called self-induction.
It is found that the flux linkage is proportional to the current through it.
i.e., f a I or f = LI
Here, L is constant and is called self-inductance of the coil or coefficient of self-induction.
S.I., the unit of self-inductance, is Henry