Question

Draw the labelled diagram of an A.C. generator. With the help of this diagram, explain the construction and working of an A.C. generator.

Accepted Answer

Construction: An electric A.C. generator consists of a rectangular coil ABCD called armature which can be rotated rapidly between poles N and S of a strong magnet using external mechanical aid. The coil is made of a large number of turns of insulated copper wire. Two ends of the coil are connected to two circular metal rings R1 and R2 called slip rings. Two carbon brushes B1 and B2 are pressed against the slip rings to maintain continuous contact while rings rotate along with the coil. Carbon brushes are connected to Galvanometer to show the flow of current in the external circuit.

AC generator, also known as alternators, is a machine that converts mechanical energy into electrical energy.

Working:
(i) When the armature is rotated in clockwise direction inside the magnetic field produced by the magnets, it cuts magnetic field lines. From the principle of electromagnetic induction, an electric current is induced in the rotating coil, whose direction is given by Fleming’s right-hand rule.
(ii) When the axle attached to two slip rings is rotated such that the arm AB moves up and CD downwards, induced current starts to flow from A to B and C to D. Thus, an induced current flow in the direction ABCD inside the generator and in the external circuit, it flows from B2 to B1
(iii) After half a rotation, arm CD starts moving up and AB moves down. As a result, the direction of induced current will be DCBA inside the generator and begin to flow from B1 to B2 in the external circuit. Thus, after every half rotation, the polarity of the current in the respective arms changes. Such a current, which changes the direction after equal intervals of time is called an alternating current.

Lakhmir Singh and Manjit Kaur Solutions for Chapter: Magnetic Effect of Electric Current, Exercise 19: Long Answer Type Questions

Lakhmir Singh Physics Solutions for Exercise - Lakhmir Singh and Manjit Kaur Solutions for Chapter: Magnetic Effect of Electric Current, Exercise 19: Long Answer Type Questions

Questions from Lakhmir Singh and Manjit Kaur Solutions for Chapter: Magnetic Effect of Electric Current, Exercise 19: Long Answer Type Questions with Hints & Solutions

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