Electric (DC) Motors
The field pole is a permanent magnet which forms a north and south pole. It's a permanent magnet becaues it's always on. It's made up of a bunch of smaller magnet domains lined up in the same direction. A shaft/axle runs through the center and is used to transfer mechanical energy.
An electromagnet is not a permanent magnet. A bolt is a nonmagnetic metal object with magnetic domains pointing in random directions. When you coil wire around it and run current through the wire, it forces the magnetic domains to line up, and it becomes ane electromagnet. The electromagnet can do the same things a permanent magnet; it has a north and south pole—opposites poles attract, and like poles repel. If you run the current in the other direction, it reverses the polarity of the electromagnet (south becomes north and vice versa). Unlike a permanent magnet, the electromagnet can be turned on or off.
Insulated wire is coiled around the armature halves. These coil windings carry electric current from the battery. As current passes through, it prodces an electromagnetic field. The timing and polarity of the magnetic field create rotation. Because we keep switching the polarity of the electromagnet, the shaft will continuously spin.
The ends of the coils are connected to commutators. The commutator is segmented into multiple plates which sit concentrically around the shaft. The plates are separated and electrically isolated from each other and the shaft. The ends of each coil are connected to to a different commutator plate.
Commutator plates sit between two brushes. The brushes make contact with the commutator segments to complete the circuit. Electricity flows through the brush, through one commutator segment, through the coil/armature, then back through the other commutator and brush on the other side.
When a motor only has two armature halves, it can get stuck between the 2 motors. The more armature loops there are, the more consistently the motor will spin.
Spinning on the armature is called the torque. Stronger torque equates to faster spin. The motor will spin faster when the electromagnets are stronger. Electromagnets are stronger when there are more wires. We can wrap more wires around the electromagnet and increase the coils around the armature loops.
For lab this week, the task was to construct a simple electric motor.
