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 Form 4 Physics: Electromagnetic induction online video lessons

Applications of electromagnetic induction

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Answer Text:
Applications of electromagnetic induction
1. A.c generator/alternator– a generator is a device which produces electricity on the basis of electromagnetic induction by continuous motion of either a solenoid or a magnet. It consists of an armature made of several turns of insulated wire wound on soft iron core and revolving freely on an axis between the poles of a powerful magnet. Two slip rings are connected to the ends of the armature with two carbon brushes rotating on the slip ring.
figelectromagneticinduction2582020929.JPG
In an external circuit the current is at maximum value at #90^0# and minimum value at #270^0#. This brings about alternating current and the corresponding voltage (e.m.f) is the alternating voltage.
They are used in car alternators and H.E.P.
2. D.c generator/alternator– in this case the commutators replaces the slip rings to enable the output to move in one direction. After a rotation of #180^0#, instead of current reversing, the connections to the external circuit are reversed so that currentdirection flows in one direction.
figelectromagneticinduction2582020930.JPG
Moving coil microphone– it consists of a coil wound on a cylindrical cardboard which opens into a diaphragm. The coil is placed between the poles of a magnet as shown.
figelectromagneticinduction2582020931.JPG
As sound waves hit the diaphragm, they vibrate and move the coil which produces induced current into the coil and then it flows to the loudspeakers.


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