Which of the following is not a part of an A.C generator?

The correct option is (c) Commutator. An AC generator (also called an alternator) is a device that converts mechanical energy into electrical energy. It works on the principle of electromagnetic induction. An AC generator consists of two main parts: a stationary part and a rotating part. The stationary part contains the field magnet, and the rotating part contains the armature. The field magnet is a permanent magnet or an electromagnet that produces a magnetic field. The armature is a coil of wire that is rotated inside the magnetic field. When the armature rotates, the magnetic field induces an alternating current (AC) in the coil. The carbon brushes and slip rings are parts of a DC generator, not an AC generator. Carbon brushes are used to transfer the current from the stationary part to the rotating part, while slip rings are used to connect the rotating part to an external circuit. The commutator is also a part of a DC generator, not an AC generator. It is a device that helps to convert the alternating current produced in the armature into direct current (DC) that can be used in an external circuit. Since AC generators produce alternating current, they do not need a commutator to convert the current. Therefore, the correct answer is (c) Commutator.