Self-inductance

Definition

Self-inductance is the property of a coil (or circuit) that allows it to oppose the change in current flowing through it by generating an electromotive force (EMF). This EMF is proportional to the rate of change of current.

5 Must Know Facts For Your Next Test

1. Self-inductance is measured in henries (H).
2. The inductance $L$ of a coil depends on its geometry and the permeability of the core material.
3. According to Faraday's Law, the induced EMF $\varepsilon = -L \frac{dI}{dt}$, where $L$ is self-inductance and $\frac{dI}{dt}$ is the rate of change of current.
4. A higher self-inductance means a greater opposition to changes in current.
5. In an AC circuit, self-inductance causes a phase difference between voltage and current.

Review Questions

• What physical quantity does self-inductance measure?
• How does changing the core material affect the inductance of a coil?
• Write down Faraday's Law as it applies to self-inductance and explain each term.

Related terms

Mutual Inductance:

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

Faraday's Law:

A fundamental law stating that an electromotive force is induced in a conductor when there is a change in magnetic flux.

Henry (H): The unit of inductance, defined as the amount of inductance required to induce one volt when the current changes at one ampere per second.