Let us discuss self-inductance
Let us take a coil of conductor. Now we will apply alternating voltage across the coil
After applying alternating voltage, alternating current starts flowing through the conductors of the coil
The alternating current produces alternating magnetic flux surround the coil. This alternatingly changing flux will link with the coil itself
As the changing flux links with the conductors of coil, there would be an induced EMF across
the coil. This is because of Faraday's laws of electromagnetic induction. The polarity of the induced EMF would be in such that it will reduce the current through
the coil. This means the induced EMF opposes the applied voltage. Polarity of induced EMF is opposite of that of source voltage
If the coil has n number of turns, rate of change of flux linkage with respect to time
is d phi dt. Then the induced EMF across the coil will be capital E equals minus n d phi dt
The flux due to a current is proportional to that current. This means phi is proportional to I or phi equals to k into I, where k is the constant
of proportionality. Now differentiating both sides with respect to time, we get d phi dt equals to k d I dt
Now we can write the EMF equation as E equals to minus n k d I dt or minus E equals to n
k d I dt. Where both n and k are constant. So the product of n and k is also constant
Let us write n into k as capital L. This L is called self-inductance of coil or solenoid
This self-inductance determines how much will be the induced EMF across the coil for a certain
rate of change of current through it. The self-inductance is a basic important property of a coil or solenoid
The unit of inductance is Henry. If a solenoid has one Henry inductance, that means the solenoid can induced EMF of one
volt when current through the solenoid is being changed by one ampere in one second
Hope you got an idea. Thank you