Self Inductance
Induced EMF in inductor L with changing current di/dt is:
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Solution
-L (di/dt)
When current I in an inductor changes, the magnetic flux through the inductor also changes (Φ=LI). This induces a 'back EMF' according to Faraday/Lenz: E=−dtdΦ=−dtd(LI)=−LdtdI The negative sign indicates that the EMF opposes the change in current (it pushes back against increasing I and tries to maintain decreasing I).
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About This Question
- Subject
- physics
- Chapter
- electromagnetic induction and ac
- Topic
- self inductance
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
-L (di/dt)
When current I in an inductor changes, the magnetic flux through the inductor also changes (Φ=LI). This induces a 'back EMF' according to Faraday/Lenz: E=−dtdΦ=−dtd(LI)=−LdtdI The negative sign indicates that the EMF opposes the change in current (it pushes back against increasing I and tries to maintain decreasing I).
This medium difficulty physics question is from the chapter electromagnetic induction and ac, covering the topic of self inductance. It appeared in the 2025 exam.
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