Self-Inductance

Self-Inductance

The phenomenon in which a changing current in a circuit induces an emf in the same circuit.

Because a changing current produces a changing magnetic field, which changes the magnetic flux through the circuit itself.

Why does self-inductance occur?

Faraday’s law of electromagnetic induction

Law that explains self-inductance

ε = -d(Φ_m)/dt

General expression for induced EMF due to changing flux

directly proportional

The magnetic flux is ____________________ to the current.

B

(i)

I

(ii)

S

(iii)

(Φ_M) = LI

Formula relating flux and current

N(Φ_M) = LI

The relation for a coil with N turns

ε = -L(d(I)/dt)

Induced EMF in terms of self-inductance

Lenz’s law

The negative sign represents __________, indicating that the induced emf opposes the change in current.

L = (|ε|)/(|d(I)/dt|)

Mathematical Representation for self-inductance

Every conductor has self-inductance because any current produces a magnetic field.

Does every conductor have self-inductance?

Wire loops, straight wires, and coaxial cables

Examples of objects with self-inductance