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.