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Self-inductance
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.
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Self-inductance
What is it?
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.
In simple words
- A changing current induces an opposing emf in the same circuit.
Recommended for Class 12
Full school-level explanation
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**
Remember
- henry (H)
- NΦ = LI
- ε=−L(di/dt)
- L=NΦ/I
Deeper understanding
Go deeper on Self-inductance: connect the definition to reasons, relationships, exceptions, and exam wording.
Common mistakes
Exam focus
Self-induction
Exam focus
Quick revision
- henry (H)
- NΦ = LI
- ε=−L(di/dt)
- L=NΦ/I
- Unit: A current in a coil produces magnetic flux. If the current changes, magnetic flux linked with the c
- Flux-Linkage Form: For `N` turns: NΦ = LI under linear conditions.
For long answers on Self-inductance: define clearly → explain the main parts → give one example → state one exam caution.
Exam Focus
Exam Focus
Important points
- henry (H)
- NΦ = LI
- ε=−L(di/dt)
- L=NΦ/I
Important formulas
- henry (H)
- NΦ = LI
- ε=−L(di/dt)
Common exam traps
- Do not say an inductor always blocks current.
- Do not omit the meaning of the negative sign: it represents opposition to change.
Long question structure
Definition → key parts → example → exam caution
Common Mistakes
Common Mistakes
- Mistake
Do not say an inductor always blocks current.
- Mistake
Do not omit the meaning of the negative sign: it represents opposition to change.
- Mistake
Do not say an inductor always blocks current.
Revision Zone
60-Second Revision
Quick cues from this topic — use them for last-minute revision.
henry (H)
NΦ = LI
ε=−L(di/dt)
L=NΦ/I
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.
NΦ = LI
- 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.
- Formula
- NΦ = LI
- Critical warning
- Do not say an inductor always blocks current.
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Exam Practice
Define
Q1. Define Self-inductance.
Explain
Q2. Explain: Unit.
Example
Q3. Give one clear example of Self-inductance and say why it fits.
Mistake
Q4. State one common mistake students make about Self-inductance.
Exam note
Q5. Write a short exam note on Self-inductance: definition, two points, one example.
Sources & References
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.