Inductance

In this article, we will discuss inductance, factors that affect inductance, Faraday’s law of electromagnetic induction, different types of inductance, self-inductance and mutual induction, and self-inductance of a solenoid, mutual induction, and the difference between mutual inductance and self inductance..

What is inductance?

Inductance refers to a magnetic field that is analogous to the change rate of the magnetic field. This way of defining inductance holds in the case of a conductor. Inductance is represented by the letter L and its SI unit is Henry. Inductance is also known as induction.

1 Henry refers to the rate of inductance needed to induce an emf of 1 volt in a conductor when there is a change in current of the conductor at 1 Ampere per second.

What is Faraday’s law of electromagnetic induction?

Electromotive force e = – L (ΔI/Δt)

Unit of Inductance = Henry 

Factors that affect inductance

Multiple factors have effects on Inductance:

1. The shape of the core
2. The material of which the core is made of
3. The sum of wire turns in the inductor

Faraday introduced the law of electromagnetic induction that cites that by differing the magnetic flux, a type of electromotive force is generated in the circuit. From this law of electromagnetic induction, the law of induction is taken. Inductance refers to the electromotive force induced to oppose the variance in current at a specific period.

What are the different kinds of inductance?

There are two kinds of inductance: self inductance and mutual induction. 

What is mutual induction?

Let’s suppose we take two coils placed close to each other. The first coil is the primary(P) coil and the other one is the secondary(S) coil. To the P-coil, a key and a battery is interconnected wherein the S-coil a galvanometer is fastened across it. When there is a variation in the magnetic or current flux connected with two coils an opposing electromotive force is induced across each coil, and this phenomenon is known as mutual induction. The relation is taken as:

Φ = I

Φ = M I

Where M refers to the coefficient of the mutual inductance of the two coils or the mutual inductance of the two coils.

The rate of variation of magnetic flux in the coil is taken as,

e = – dϕ/dt = – d(MI)/dt

e = – M  dI/dt

Mutual inductance formula 

M= µ0µrN1N2A/l

Where,

• l refers to the length of the coil in m
• A refers to the cross-sectional area in m2
• N refers to the number of turns in the coil
• μr refers to the relative permeability of the soft iron core
• μ0 refers to the permeability of free space

What is self induction?

When there is a variation in the magnetic or current flux of the coil, an opposed generated electromotive force is induced. This phenomenon is coined as self induction. When the current flows through the coil at a point in time, it is seen that the magnetic flux is directly analogous to the current of the circuit. The relation is taken as:

Φ = L I

Where L is the coefficient of self inductance or self inductance of the coil. The self inductance depends on the number of turns in the coil, the permeability of the material, or the cross-sectional area.

The rate of change of magnetic flux in the coil is taken as,

e = – dϕ/dT = -d (LI)/dT

or e = – L  dI/dT

Self inductance formula

L = N ϕ/I

Where,

• I refer to the current in amperes
• Φ refers to the magnetic flux
• N refers to the number of turns
• L refers to the self-inductance in Henries

Difference between mutual inductance and self inductance

1. Self inductance refers to the traits of the coil itself, whereas mutual inductance refers to the traits of a pair of coils.
2. The produced current developed in the neighbouring coil opposes the growth of current in the coil when the main current in the coil rises, whereas, the produced current opposes the growth of current in the coil when the main current in the coil rises.
3. The produced current developed in the neighbouring coil opposes the decay of the current in the coil when the primary current in the coil declines, whereas, the produced current opposes the decay of current in the coil when the primary current in the coil declines.

Conclusion 

Inductance refers to a magnetic field that is analogous to the change rate of the magnetic field. This way of defining inductance holds in the case of a conductor. Inductance is represented by the letter L and its SI unit is Henry. Inductance is of two kinds that are self-inductance and mutual induction: Mutual and self inductance.