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.