Self-inductance

Definition

Self-inductance is the property of a conductor by which a change in current induces an electromotive force (EMF) in the same conductor. It is quantified by the inductance \$L\$ and measured in Henrys (H).

5 Must Know Facts For Your Next Test

1. The self-induced EMF, according to Faraday's law, is given by \$ \text{EMF} = -L \frac{dI}{dt} \$.
2. The SI unit of self-inductance is the Henry (H).
3. Self-inductance depends on the geometry and material properties of the inductor.
4. For a solenoid, self-inductance can be calculated using \$ L = \mu_0 n^2 A l \$ where \$\mu_0\$ is the permeability of free space, \$n\$ is the number of turns per unit length, \$A\$ is the cross-sectional area, and \$l\$ is the length.
5. An increasing current through an inductor generates a magnetic field that opposes this increase due to Lenz's Law.

Review Questions

• What physical quantity does self-inductance measure?
• How does changing current affect a conductor with self-inductance?
• Write down the formula for EMF induced by self-inductance.

Related terms

Mutual Inductance:

The property where a change in current in one coil induces an EMF in another nearby coil.

Inductor:

A passive electrical component that stores energy in its magnetic field due to its inductance.

Faraday's Law of Induction: \$ \text{EMF} = - \frac{d\Phi_B}{dt} \$, describing how a time-varying magnetic flux through a circuit induces an electromotive force.