Electromagnetic Induction

Faraday's Laws of Electromagnetic Induction

 * 1) Whenever, a coil is associated with a changing magnetic flux , an emf is induced in it.
 * 2) The emf induced in a coil is directly proportional to the rate of change of magnetic flux.

Lenz's Law
Whenever a coil, is associated with a changing magnetic flux , emf is induced in the coil such that it opposes the cause of it.

Eddy Currents
Eddy currents are formed in conductors of large surface areas. In such conductors, whenever an emf is induced , the electrons in it start moving in circular orbits like whirlpools or eddies.

Self Induction
When a circuit is subjected to alternating current, the magnetism due to electric current changes. Thus, the coil is subjected to a changing magnetic flux under it's own influence.

e = -L [di/dt]

Mutual Induction
When a primary coil is subjected to alternating Current and a Secondary coil is placed adjacent to it, then the secondary coil comes under the influence of the primary coil's changing magnetic flux.

e = -M [di/dt]

Induction
Energy = 1/2 Li2

Power = Work / TIme

Displacement Current
According to Ampere's Circuital Law ;

∫ B dl = μI

But for an inductive circuit ;

Transformer
Transformer Works on the principle of Mutual Induction.

np/ns = ep/es = is/ip

A.C. Generator
An A.C. generator works on a simple principle, that an emf is induced when there is relative motion between magnetic field and conductor. An AC motor xonsists of an iron core on which copper wire is wound, and this core is made to rotate in a magnetic field. Thus, the coil is subjected to a changing magnetic flux. The arrangement of the core is such that current flows out of the brush B1 in first cycle, and out of the brush B2 in second cycle. In this way, an Alternating Current can be generated.

Alternating Current
In an alternating Current, the emf and current vary with time as harmonic functions (sine or cosine).

Alternating Current with LCR Series
The resonant frequency of a LCR circuits depends upon its L & C values.