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Cheat sheet · Class 12 · CBSE · Science Physics

Electromagnetic Induction cheat sheet

The whole chapter on one page: key formulas, facts and the points to remember, for quick revision before a test.

CBSE Class 12 · Physics

Cheat sheet

Chapter 6Electromagnetic Induction

Lenz: induced current opposes the change that causes it.

1. Faraday & Lenz

ε=−dΦdt\varepsilon = -\dfrac{d\Phi}{dt}Φ=BAcos⁡θ\Phi = BA\cos\theta

Lenz's law follows from conservation of energy.

2. Motional EMF

ε=Blv\varepsilon = Blv
ε=12Bωl2\varepsilon = \tfrac12B\omega l^2 (rotating rod)

3. Inductance

ε=−LdIdt\varepsilon = -L\dfrac{dI}{dt}L=μ0n2AlL = \mu_0n^2Al (solenoid)
ε2=−MdI1dt\varepsilon_2 = -M\dfrac{dI_1}{dt}U=12LI2U = \tfrac12LI^2

4. AC Generator

ε=NBAωsin⁡ωt\varepsilon = NBA\omega\sin\omega t

Eddy currents: induction furnace, braking, damping; reduced by laminated cores.

5. Key Points

  • Unit of flux: weber.
  • Inductance opposes change in current.
  • Henry is the unit of L.
  • Fleming's right-hand rule for direction.

Remember: ε = −dΦ/dt | Blv | L, M | generator

Electromagnetic Induction: questions and notes

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