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# CBSE Class 12th Physics Notes for Chapter 6 Electromagnetic Induction

CHAPTER 6 ELECTROMAGNETIC INDUCTION

• The magnetic flux through a surface of area A is placed in a uniform magnetic field B is defined as: ϕB = B.A= BA cos θ where θ is the angle between B and A.

• Faraday’s laws of induction imply that the emf induced in a col of N turns is directly related to the rate of change of flux through it.

• Lenz’s law states that the polarity of the induced emf is such that it tends to produce a current which opposed the change in magnetic flux that produces it.

• Changing magnetic fields can set up current loops in nearby metal bodies. They dissipate electrical energy as heat. Such currents are called eddy currents.

• Inductance: It is the ratio of the flux-linkage to current.

• A changing current in a coil can induce an emf in a nearby coil.

• When the current in a coil changes, it induces a back emf in the same coil.

• AC generator: In an ac generator, mechanical energy is converted to electrical energy by virtue of electromagnetic induction.