The armature coil is hidden so that it is easier to see the commutator in action and as the armature passes through the horizontal position, the electromagnet poles are reversed. Because of the inversion, the north pole of the electromagnet is always above the axis so as to repel the magnetic field of the north pole of the field magnet and attract the pole of the south pole.
An electric motor has the same parts being small or large. It is composed of two small permanent magnets martin 41bs36 5/8 , a switch, two brushes and an electromagnet made by wrapping wire around a metal piece. The rotor will almost always have three poles instead of two and we have two good reasons for this:
– So that the engine has better dynamics. In a two-pole motor, if the electromagnet is at break-even point, when the motor starts, the armature may lock. This is not the case with a three-pole motor.
– every time the switch reaches the point where it reverses the field in a two-pole motor, it short-circuits the battery for a moment, this causes the power to be expended and unloaded the battery unnecessarily. A three-pole motor solves this problem.