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Electromagnetic induction — the generation of EMF by changing magnetic flux — is one of the most consequential discoveries in physics, underpinning generators, transformers, and modern electrical infrastructure. It carries 3% JEE weightage with problems spanning motional EMF, rotating coils, inductance calculations, and energy storage.

Faraday's law ($\varepsilon = -Nd\Phi/dt$) is the central equation. The flux $\Phi = BA\cos\theta$ can change via three routes: varying field strength $B$, changing loop area $A$ (motional EMF), or rotating the loop (changing $\theta$). Lenz's law provides the direction — the induced current always opposes the flux change, a direct consequence of energy conservation.

Self-inductance ($L$) and mutual inductance ($M$) extend induction to circuits: a changing current in one coil induces EMF in itself ($\varepsilon = -LdI/dt$) or in a nearby coil ($\varepsilon = -MdI_1/dt$). Energy stored in an inductor ($U = LI^2/2$) parallels capacitor energy storage. LC circuits oscillate at $\omega = 1/\sqrt{LC}$, the electrical analog of SHM.

JEE problems test both conceptual understanding (Lenz's law direction, EMF vs. flux distinction) and computational skill (motional EMF on rails, rotating rod formulas, inductance calculations).