let us discuss different experiments which
shows electro magnetic induction. here we
can see, this is a circular coil connected
with a galvanometer, and say if a magnet is
brought close to the coil here we can see
that, the magnetic lines from the magnet,
passing through the coil are increasing. so
when the magnet comes closer to the coils,
we can see, a current induces which we can
see in the deflection of galvanometer. and
if the magnet is brought back here, we can
see that the direction is changed, and the
galvanometer shows deflection in opposite
direction. and continuosly if the magnet starts
oscillating here back and forth, we can see
the direction of current in galvanometer continuously
changes, or we can say due to this type of
motion between, a relative motion between
magnet and the coil, an alternating current
is induced in the circuit it is because of
the e m f induced in the coil. similar to
this here we can see another experiment, there’s
a uniform magnetic field, in which there’s
a rectangular loop placed. and a part of loop
is outside the magnetic field at which, a
galvanometer is connected in the circuit.
and here we can see, if the loop is pulled
out of the magnetic field, here we can see
that the total flux, which is passing through
the loop is decreasing. and due to which,
we can see, deflection is their in galvanometer
and here we can see, it is because of an e
m f induced, due to change in flux through
the loop. similarly if the loop is pushed
into the magnetic field, the flux increases
and the direction of deflection in galvanometer
is opposite that means, an opposite e m f
is induced. similar to this here we can see
another experiment, in which we can see there
are 2 smooth rails p and q, and to these rails,
a bulb and a galvanometer is connected. and
the rails are, in uniform magnetic field.
here we can see a uniform magnetic field in
the direction into the plane of this paper
is applied, and a rod ay b is also placed
on it. say if we start moving this rod ay
b, here we can see the rod will start cutting
the magnetic flux of this magnetic field.
or we can say the loop which is formed by
the circuit, on the left side of the rod the
total magnetic flux associated with it is
increasing due to the motion of rod. because
of which an e m f is induced, and here we
can see the bulb is glowing, and the galvanometer
is showing a deflection. if the rod is stopped,
we can see the bulb stops glowing, and the
galvanometer deflection comes to zero, because
no change in flux takes place here. if the
rod is displaced in the opposite direction
we can see again bulb glows but the direction
of deflection in galvanometer is opposite.
so these all experiments are giving us the
idea about how electro magnetic induction
takes place. and the basic phenomena is whenever
there’s a relative motion between magnetic
field and the conductor, whether field is
moving or the conductor is moving in such
a way that total magnetic flux associated
with the loop or conductor changes, an e m
f is induced which can cause an induced current
in the circuit if the circuit is closed.
