Current generation

ELECTROMAGNETIC INDUCTION
 Induced current is
produced from a
changing magnetic
field.
 Called
electromagnetic
induction

 Fleming right hand
rule is used to
determine the
direction of
induced current
when a conductor
cuts through the
magnetic field lines
perpendicular.

 The bulb is lighted when a
magnet moves into a
solenoid or coil.

 The magnetic lines are cut
by the solenoid

 When the magnet is remain
static, no induced current
available

LENZ’S LAW

 INDUCED
CURRENT IS
ALWAYS FLOWS IN
SUCH A
DIRECTION SO AS
TO OPPOSE THE
CHANGE (MOTION)
PRODUCING IT

DIRECTION OF INDUCED CURRENT
 When the North pole
of a magnet moved
into a solenoid, the
end P becomes a
North pole to produce
a force of repulsion to
oppose the change of
magnet motion.

Galvanometer is deflected to
………

DYNAMO
 APPLICATION OF
ELECTROMAGNETIC
INDUCTION
 Dc generator

Working principle of dc generator

 The coil is rotated by external force and cuts the
magnetic force. An alternate e.m.f is induced in the coil,
but a dc output is obtained by using split ring
commutator.
 The two halves of the split ring commutator exchange
contact with the carbon brushes every half rotation
 The cutting of magnetic flux is maximum when the coil is
at horizontal position. It decreases when as the coil
rotates from horizontal to vertical position.
 Magnitude of induced flux changes whenever the position
of coil changes.

 If the split ring commutator is
replaced with two slip rings, the
output is ac. The slip rings are always
in contact with the same carbon
brush. The output current changes
direction every half turn.

Current generation

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