PhysicsChapter 6: Alternating Current
Self-Inductance
Self-inductance
Definition
Self-inductance is the property of a circuit by which a changing current in that circuit produces an induced emf that opposes the change in current.
Unit
A current in a coil produces magnetic flux. If the current changes, magnetic flux linked with the coil also changes. According to Faraday's and Lenz's laws, an emf is induced. For an ideal linear inductor: ε = −L(di/dt) where: `L` = self-inductance. The negative sign represents Lenz's law. SI unit: **henry (H)**. One henry corresponds to an induced emf of one volt when current changes at one ampere per second.
Flux-Linkage Form
For `N` turns: **NΦ = LI** under linear conditions.
Formula / Key Relation
**ε=−L(di/dt) L=NΦ/I**
Exam preparation
Exam Focus
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Review the key facts, formulas and checks before you move on.Self-Inductance
Sticky Notes · Quick Revision
Self-induction:
- changing I
- → changing Φ
- → induced emf
- `ε=-L di/dt`
- Unit: H
60-second revision
- A changing current induces an opposing emf in the same circuit.
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