Children we studied that current is of
two types and that is AC and DC now
especially when we were studying about
AC current we studied AC means
alternating current a current in which
the direction of current keeps on
changing the current flows in one
direction then current flows in another
direction how is this possible and how
exactly does an AC generator work right
now to understand the working of an AC
generator let us enter into empty
Educare science lab is a virtual
classroom for you right so let us look
at this particular science lab
of AC generator the first part is a
armature coil right so when we had seen
this armature coil in a motor also so
what is armature coil it is a
rectangular metal slab on which there is
a coiling of copper wire so copper wire
is called on a rectangular metal slab
and this is called as a armature coil
right we'll go to the next all pieces of
a magnet a pole piece of a magnet means
if that side is are not pole then the
other side there should be a South Pole
and this is South Pole that side should
be a not pole so either in such a
instrument a pole pieces of a magnet is
taken or you can also take a horseshoe
shaped magnet a horseshoe shaped magnet
right with only the poles which are kept
here right so so either of the thing can
be taken we'll go to the next this part
is called slip ring it plays a very
important role inside you can see inside
the slip ring are the two wires and this
wires can slip through this particular
rings and that is why this rings are
called as slip rings right here are the
brushes right this is a brush and after
this brush is the galvanometer we know
galvanometer is a device which measures
the direction of current and also
galvanometers a device which shows the
current and also detects the direction
of current right going further let's see
this
now taking a look at the slip rings from
inside you can see one of the wire is a
shorter wire and the shorter wire is
connected to the first of the slip ring
the longer wire is connected to the
second slip ring right that is how they
are connected from inside going further
you can see that there are lines of
force the lines of force are starting
from knot and going to South so as soon
as the armature coil ABCD is going to
rotate in the magnetic field what is
going to happen as soon as it rotates
first thing is lines of Rosa cut right
the second thing that happens is the
magnetic field in the armature coil
changes right and because of this
current is induced right so the magnetic
field is being cut and current is being
induced now how do we understand in
which direction the current is being
induced the direction of the induced
current is given by Fleming's right hand
rule which we learnt so according to
this rule if the thumb shows the
direction of motion the forefinger shows
the direction of magnetic field then the
central finger will show the direction
of the induced current okay students we
have just now seen
Fleming's right hand rule and from
Fleming's right hand rule does one thing
we have understood if the direction of
motion is upwards then the current is
inwards now I'm going to use this in
understanding how a generator works now
here when the coil ABCD armature coil
ABCD rotates in a clockwise direction a
B is going to move upwards and when a B
moves upwards the current has to be
inwards so let us see how it is produced
the current is flowing now the current
has gone in to be one right you have
seen the current has entered from be one
gone into the galvanometer and the
current is going from b1 to b2 so let's
see this further right me when to be to
now in the second half of the cycle now
first half of the cycle we have seen the
current has gone from b1 to b2 let's
take it further now the current has
started from b2 right and now the
current is going to be 1 that means the
direction of current has changed
