Question

Give the principal of working of an AC generator .

Answer 1

Generator :-
A generator is an electrical machine that produces electrical energy from mechanical work,just the opposite of what a motor does.
In a generator the shaft is rotated by some mechanical means,such as an engine or a turbine starts working and an EMF is induced in the coil .
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AC generator :-
Now to get sinusoidally varying alternating current,we need s source which can generate sinusoidally varying EMF. An AC generator also called AC dynamo,can be used as such a source . It converts mechanical energy into electrical energy producing an alternate EMF.

Principal AC generator :-
An AC generator is based on the phonemenon of electromagnetic induction,which states that when a coil is rotated In uniform magnetic field magnetic flux linked with a conductor(or coil) changes,an EMF is induced In the coil.

Answer 2

$\huge \bf{ \red{answer}}$

$\bf{\: principal}$

It is based on the principle of electromagnetic induction . when a coil is rotated about an axis perpendicular to the direction of uniform magnetic field, an indused emf produced across it.

$\bf{construction}$

The AC generator consists of the following parts :

$\sf{1. \: armature}$

A rectangular coil ABCD consisting of a large number of turns wound over a soft iron core is called armature. the soft iron core is used to increase the magnetic flux.

$\sf{2. \: field \: magnet}$

it is a strong magnet having concave poles. the armature is rotated between the two poles of this magnet so that axis of armature is perpendicular to magnetic field lines. in a small AC generator the magnet is the permanent magnet but in Big AC generators it is an electromagnet.

$\sf{3. \: slip \: rings}$

the leads from the arms of armature AC connected to two slip rings S, which rotate with the loop .

$\sf{4. \: brushes}$

the rings slide against stationery contacts called brushes . these brushes are made up of carbon. these brushes are connected to the output terminals p and q.

$\bf{working}$

the working of AC generator can be understood with the help of various positions of the armature .

suppose at time 't' =0 , the plane of the loop is perpendicular to B . as the loop rotate from position t=0 to position t=T/2 , induced EMF changes from zero to maximum value and then becomes zero again, hence induced EMF is zero. as the loop moves from position t =T /2 to position t=T , the EMF again changes from zero to maximum value and then again becomes zero .

Thus the output of the AC generator varries sinusoidally with time . The induced EMF does not depend upon the shape of the loop but depends only upon area of the loop..