Which of the following is not a component of a d.c. electric motor?

The components of a DC electric motor include an armature, a commutator, field magnets, carbon brushes, and sometimes, brushes or slip rings. The armature is the rotating part of the motor that converts electrical energy into mechanical energy. The commutator is a device that changes the direction of the current flowing through the armature, ensuring that it continues to rotate in the same direction. The field magnets produce a magnetic field that interacts with the current flowing through the armature, causing it to rotate. Carbon brushes are used to transfer electrical current between stationary wires and moving parts of the motor, such as the commutator or slip rings. Slip rings are used in some types of motors as an alternative to the commutator to transfer electrical current between the stationary wires and the rotating parts of the motor. Therefore, the component that is not a component of a DC electric motor is slip rings. Although slip rings can be used in some types of electric motors, they are not commonly used in DC electric motors. Instead, DC motors typically use a commutator to transfer electrical current between the stationary wires and the rotating armature. So the correct answer to the question is "Slip rings".