# Self-Inductance

## Self-Inductance

Inductance can be defined as the electromotive force generated to oppose the change in current in particular time duration. According to Faraday’s law, unit of Inductance:

$$Inductance=\frac{Volt\operatorname{Sec}ond}{Ampere}=Henry$$.

There are two types of Inductance are there:

• Self-Inductance
• Mutual Inductance.

What is a Self-Inductance?

Self – Inductance is defined as the property of the coil due to which it opposes the change of current flowing through it. Inductance is attained by a coil due to the self – induced emf produced in the coil itself by changing the current flowing through it.

When there is a change in current or magnetic flux of the coil, an opposed induced electromotive force is produced, this phenomenon is termed as self – Inductance. When the current start flowing through the coil at any instant, it is found that the magnetic flux becomes directly proportional to the current passing through the circuit (φ α I).

Magnetic Flux (φ) α Current (I).

φ = I

φ = L x I

Where,

L = Self – Inductance of the coil/ Coefficient of Self – Inductance.

The self-inductance depends on the cross sectional area and the number of turns in the coil.

The rate of change of magnetic flux in the coil is given as:

$$e=-\frac{d\phi }{dt}=-\frac{d(LI)}{dt}=-L\frac{dI}{dt}$$,

$$e=-L\frac{dI}{dt}$$,

∴ $$Self\,Inductance(L)=-\frac{e}{\left( \frac{dI}{dt} \right)}$$.

According to Lenz’s Law, the induced emf opposes the direction of the rate of change of current. So, their value is same but sign differs.