Question

working of an AC generator ?

Answer 1

Parts of an AC Electric Generator

Insulated Copper wire: A rectangular rotating coil of wire ABCD

Magnet Poles: A magnet as placed above ie North Pole and South Pole. This creates a magnetic field as shown above. The rectangular coil is placed between these magnets

Split Rings: Two disjoint C-shaped rings R1 and R2 are internally attached to the Axle.. Ends of the coil are connected to R1 and R2. The inner portion of these rins are made of non-conducting material

Axle: The split rings are placed on the axle which is made to rotate freely from an external source.

Brushes: The outside of the split rings are connected to conducting brushes B1 and B2. B1 and B2 is kept pressed on R1 and R2 respectively.

Galvanometer : To measure current. The outer ends of the brushes are connected to the galvanometer to measure the current

Working

The axle is rotated such that it moves in the clockwise directions that is AB moves up and CD moves down.

According to Fleming's Right Hand rule, the induced current is setup in the coil along B1-> AB -> BC -> CD -> B2. This means that the external current flows from B2 to B1.

After half a rotation, arm CD starts moves up and AB moves down.

According to Fleming's Right Hand rule, the induced current is setup in the coil along B2-> AB -> BC -> CD -> B1. This means that the external current flows from B1 to B2.

Thus after every half rotation of the coil, the current changes direction. This is called an AC current.

AC current(Alternating current) : Changes its direction after equal intervals of time. It is easier to transmit this current over long distances due to lesser loses and hence this is the current that is supplied to our houses from the electricity department.

Answer 2

Explanation:

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

$\bf{\: principal}$

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..