Electromagnetic Induction Flashcards
Electromagnetic Induction
Whenever the magnetic field passing through a coil changes, an emf appears in the coil. This phenomenon is called electromagnetic induction
Unit of Magnetic Flux
The unit of magnetic flux is the weber (Wb)
The Weber
If the magnetic flux density over an area of 1 m*2 is 1 tesla then the flux density through the area is 1 weber
Faraday’s Law of Electromagnetic Induction
States that the size of the induced emf is directly proportional to the rate of change of flux
Lenz’s Law
States that the direction of an induced current is always such as to oppose the change producing it
Electric Generator
An electric generator is a device that converts mechanical energy to electrical energy
Mutual Induction
If a changing magnetic field in one coil causes an induced emf to appear in a nearby coil there is said to be mutual induction between the two coils
Self Induction
Whenever the current through a coil changes, the magnetic field surrounding that coil changes, This changing magnetic field induces an emf in the coil that opposes the changing current. This phenomenon is called self induction
Coils/Inductors and A.C./D.C.
A coil (inductor) opposes the flow of direct current (d.c.) with its ohmic resistance A coil (inductor) opposes the flow of alternating current (a.c.) with its ohmic resistance and the back emf induced in it
Charged Capacitor and A.C./D.C.
A charged capacitor blocks d.c.
A capacitor conducts a.c. since it charges and discharges as the a.c. changes direction
The Transformer
A transformer is a device used to change the value of an alternating voltage
Step Up/Down Transformers
If Ns is greater than Np, the Vo is greater than Vi and it is called a step up transformer
If Ns is less than Np, then Vo is less than Vi and it is called a step down transformer
