Ch 6 covers electromagnetic induction — Faraday's laws, Lenz's law, motional EMF, inductance (self and mutual), eddy currents, and the AC generator.
Faraday: EMF induced = −dΦ/dt (Φ = BA cosθ). Change in flux can be due to changing B, area, or angle. Lenz's law: induced current opposes the change that causes it (conservation of energy). Motional EMF: conductor of length l moving at velocity v in field B → ε = Blv.
Self-inductance L: an EMF is induced in a coil due to change in its own current. ε = −L(dI/dt). L for solenoid = μ₀n²Al. Energy stored = ½LI². Mutual inductance M: change in current in one coil induces EMF in neighbouring coil. ε₂ = −M(dI₁/dt). M depends on geometry and orientation. Eddy currents: induced in bulk conductors, cause heating (used in brakes, induction furnaces).
Download: https://ncert.nic.in/textbook/pdf/leph106.pdf | Part I: https://ncert.nic.in/textbook/pdf/leph1ps.zip
Lenz's law states that the induced current flows in a direction that opposes the change in magnetic flux that caused it. It follows from conservation of energy — if the induced current aided the change, flux would increase, inducing more current, in a never-ending cycle of free energy. Lenz's law ensures that we must do work to change the flux, keeping energy conserved.
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