Question

Explain the function of the following part of an electric motor. Brushes.

Answer 1

Hint:A motor is an electrical device that converts electrical energy into mechanical energy. Electric motors generate force in the form of torque through the interaction between the motor’s magnetic field and the electric current in the wire winding. The torque generated is applied to the motor’s shaft. The brush helps conduct the current and complete the circuit in a motor.

Complete step by step answer:
The working principle of DC Motor mainly depends upon Fleming Left-Hand rule. The armature coil is placed between the magnetic poles. An external DC source, a battery, is connected to the armature coil and current starts flowing through it. Since the current-carrying armature coil lies inside a magnetic field, they will experience a force which tends to rotate the armature.

Simply put, a brush is an electrical contact which conducts current between stationary wires and moving parts in a rotating shaft. The brush is usually made of one or more carbon blocks and can come with one or more shunts or terminals.

Since the slip rings or commutator are two half rings connected to the voltage supply, if the brushes are not used and a fixed connection is made then after rotation of the armature coil, there would be a lot of torsional force on the connection which would lead to the breaking of the circuit. Hence to prevent that and to maintain the smooth transfer of current from the battery to the armature coil, brushes are used.

Note:There is a drawback of brushes though; since for every rotation of the armature coil, the brushes rub against the commutator, the friction causes wear and tear of both the brush and the commutator. Hence brushless AC motors are a better alternative nowadays.