Question

Describe the working of an A.C generator with the help of labeled diagram.What changes must be made in the arrangement to convert it in a D.C generator?

Answer 1

It works on the principle of electro magnetic Induction

Answer 2

Answer:

An electric generator consists of a rotating rectangular coil ABCD placed between two poles of permanent magnet. The coil ends are connected to the two rings R1 and R2 . The inner sides of the ring are insulated. The stationary brushes B1 and B2 are kept pressed separately on rings R1 and R2. The rings are internally attached to the axle. The axle is mechanically rotated from outside to rotate the coil inside the magnetic field. The outer ends of the rings are connected to the galvanometer.

Working of Electric generator:

When the axle connected to the two rings is rotated, then the arm AB moves upward and CD moves downward in the magnetic field produced by the permanent magnet. Let the coil AB is rotated in clockwise direction. Using Fleming’s right-hand rule, the induced currents are set up in directions along AB and CD and an induced current flow in ABCD. If there are large number of turns in the coil, then the current adds up in each current to give large current. This means that the current in the external current flows from B2 to B1. After half turn, arm AB moves in downward direction and CD moves in upward direction. Now the direction of induced current is reversed and now current flows in DCBA direction. The current now flows from B1 to B2. Thus, after every half rotation, the direction of the current reverses. This current is known as alternating current which changes the direction of current periodically.

AC generator can be converted into a DC generator with the help of a split ring commutator.