In an electric motor, the direction of current in the coil changes once in each:(a) two rotations   (b) one rotation   (c) half rotation   (d) one-fourth rotation

Explanation

A device called a split-ring or commutator consists of two conductive arcs separated by an insulator in an electric motor. It allows reversing the direction of the current in the coil of the motor once in each half rotation due to which the coil continues to rotate as long as current from the battery is passed through it.