Name: An Elementary Study of Domestic Electric Circuits
Uploaded: 2019-07-19
Duration: 5 min 52 s
Description: The electricity we consume is produced through electromagnetic induction at power plants. In this video, we will see the journey of electricity from the powe...

Question

Explain with diagram the action of A.C generator.

Accepted Answer

Principle of A.C generator: Electric generator works on the principle of electromagnetic induction. Generator is a device to convert mechanical energy into electrical energy. When the coil is rotated in the magnetic field the direction of the induced current changes alternately.

Construction of A.C generator: Two pole pieces North-South of a permanent magnet. An armature consisting of a number of turns of rectangular coils. Two metal slip rings $R_{1}$ and $R_{2}$ connected to the two terminals of the coil. Two stationary conducting brushes $B_{1}$ and $B_{2}$ are connected to $R_{1}$ and $R_{2}$ respectively.

Working: When the coil rotates the side AB moves downwards and CD moves upwards cutting across the magnetic field. Electric current is developed in the coil due to electromagnetic induction. Applying Fleming's right hand rule the direction of induced current will be along BA and DC. Now the current will complete its flow along DCBA then through $R_{1}$ to the external circuit or load and returning through $R_{2}$ .

After the completion of half rotation the side AB will occupy the lowermost and CD the uppermost position. When the armature continues its rotation the side AB moves upwards and CD moves downwards cutting across the magnetic field. In this second half of rotation the current will flow along AB and CD completing its circuit along ABCD then through $R_{2}$ to the external load and returning through $R_{1}$ . Thus the polarity changes alternately. Then the same cycle continues as the armature goes on rotating continuously. Thus the direction of current in the external circuit changes for every half rotation. Such current is known as alternating current (A.C) and the generator is known as A.C Generator.

Note: Using split rings replacing slip rings will generate (D.C) direct current.

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