Please explain the process of self induction?

Self induction

When a current is established in a closed conducting loop, it produces a magnetic field. This magnetic field has its flux through an area bounded by the loop. If the current changes with time, the flux through the loop changes and hence an emf is induced in the loop. This process is called self induction as the emf is induced in the loop by changing the current in the same loop.


Self induced emf = -Ldi/dt

Where L is called self-inductance of the loop and is a constant depending on the geometrical construction of the loop.

Self inductance of a long solenoid

Self inductance of a long solenoid is

L = µ0n² πr² l

Where L = Self inductance

n = number of turns per unit length of the solenoid

r = radius of the solenoid

l = length of the solenoid

So the self-inductance depends only on geometrical factors.

A coil or a solenoid made from a thick wire has negligible resistance but a considerable self-inductance. Such an element is called an ideal inductor and is indicated by a coil symbol.

The self induced emf in a coil opposes the change in the current that has induced it in accordance with the Lenz’s law. If the current in the coil is increasing, induced current will be opposite to the original current. If the current in the coil is decreasing, the induced current will be along the original current trying to stop its decrease.

do not get confused with the minus sign...its just to signify the direction... which can anyways be found by lenz law...just try to find the magnitude and get the direction seperately by using lenz law..