Science · Class 12
Electromagnetic Induction
Learn Electromagnetic Induction with notes, examples, and practice questions.
3 sections15–25 min read6 MCQs · 2 examples
Chapter Overview
Changing magnetic flux induces EMF — Faraday's law. Lenz's law gives direction; self and mutual inductance store magnetic energy.
Laws
Magnetic flux
Φ = B·A cos θ
Faraday
ε = −dΦ/dt
Motional EMF
ε = Blv
Self-inductance
ε = −L dI/dt ; L = NΦ/I
Energy
U = ½LI²
AC Generator Preview
- Rotating coil in B → sinusoidal ε
- Peak EMF ε₀ = NABω
- Flux linkage varies as cos ωt
Solved Examples
Step-by-step solutions — read each step before checking the final answer.
Faraday
Flux changes 0.02 Wb in 0.1 s.
- 1ε=ΔΦ/Δt=0.2V
Answer
0.2 V
Motional EMF
B=0.5T, l=2m, v=10m/s.
- 1ε=Blv=10V
Answer
10 V
Key Points to Remember
- ✓ Lenz: induced current opposes flux change
- ✓ Eddy currents: heating, braking
- ✓ Inductor opposes current change
Exam Tips
- • Sign in Faraday from Lenz
- • Units: Wb for flux, H for inductance
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Formula Cheat Sheet
Quick reference — NCERT board exam formulas
Induction Laws
- Magnetic flux:Φ = B·A cos θ
- Faraday:ε = −dΦ/dt
- Motional EMF:ε = Blv
- Self-inductance:ε = −L dI/dt ; L = NΦ/I
- Energy:U = ½LI²
- AC peak EMF:ε₀ = NABω
Practice MCQs — Electromagnetic Induction
Test your understanding with topic-wise multiple choice questions. Explanations appear after each answer.
Question 1 of 6Score: 0/0
Faraday law relates ε to: