Let's start with a circuit. You have a battery, some wires, and a device that uses electricity, such as a light bulb. Electricity will flow through the circuit, but if there is a break in the wire, the circuit will stop working. You can use a switch to help you turn the flow on and off easily. This is called a conventional flow. However, if you flip the battery the other way, the current will flow the other way. This differs depending on the device that will need electricity. Now, we will talk about magnets. A magnet has a north pole and a south pole. It will attract other metal objects like paper clips. If you bring another magnet near it, the opposite poles will attract while the same poles will repel. Magnets can turn off, or be closed, and so they are called permanent magnets. If you drill a hole in the middle of a permanent magnet and put the same pole, it will rotate until you reach the opposite side of the magnet. A metal bolt is like a magnet, but it's magnet domains are facing random directions. If you wrap a wire around the bolt and put it in a circuit, the current through the wires forces the magnetic domains to line up. That is an electromagnet.
Electromagnets can do whatever a permanent magnet can do. It can pick up metal objects, has a north and south pole which will repel and attract. The special thing about the electromagnet is that it can be turned on or off. Permanent magnets can do that because the magnetic domains are lined up always. If you flip the battery, the current flows the other way. The north would become south and the south becomes north. This is called reversing the polarity of an electromagnet. Remember how we were talking about spinning magnets, you can do the same with electromagnets. As soon as you connect the wires, the magnet will spin. If you add the opposite on both sides, the magnet will keep spinning. The two side magnets can be replaced with stronger curved magnets. And instead of a bolt with wires, we will use a metal loop. This is called an armature. Think of the magnet flat with the south pole facing up. You can make it spin by switching the wires, but that requires a lot of work. You can add something to the armature called a commutator. It’s a ring with gaps on the opposite sides. The commutator will spin along with the armature. You now add 2 brushes to the side of the commutator. The brushes will slide along as the commutator spins and they are also spring-loaded, ensuring they always maintain contact. The current flows through the wire, the brush then the commutator ring, the armature, then back to the commutator ring, and then back to the brush. As you come around while the armature spins, the brushes will switch contact to the other side of the commutator ring. This is happening at the same time because there are 2 brushes. Before the sides switch, the sides will go opposite ways. Once the sides switch, the current flows in the other direction again. It will continue to spin as long as it is connected to a battery. Disconnect the battery and no more electromagnet, and the spinning stops. So far, we have used 1 loop on the armature. This will cause the motor to have an irregular speed with the brushes halfway between commutator segments. What we can do is split the commutator ring and then add another loop, so first, the brushes are in contact with the commutator segments, which turns on 1 of the loops. Once you reach the halfway segment, the brushes switch and the next pair of commutator segments turn on and it starts spinning while the other one gets turned off. This keeps happening while the motor spins. Some electromagnets will add many loops to the armature. This ensures there will be a continuous spinning motion on the motor. This spinning force in the armature is called a torque. Stronger torque means a faster spin.
There are some things you can do to improve the torque of the motor. Electromagnets are stronger when there are more wires. If each of the loops is made of many wires, the motor will have stronger electromagnets, which means it will spin faster. Another way to improve it is to use more electricity. Let’s learn a few terms. The part that doesn’t move is called the stator, which in this case is the two permanent magnets on the side. The fit inside the edges of a motor case. The armature in the middle is also called a rotor. Remember, this is the part that spins. The axle goes through the middle and sticks out of the back of the motor case. This is called a DC motor. If you have a device that moves and is powered by a battery, there’s a good chance there is a DC motor in it. Different motors spin differently, but they still spin. This can be a fan in your room or its side-to-side motion. Or an electric cutting knife, which each blade is going back and forth. It all starts with the spinning of the motor, then a gear, which then pushes these two pieces back and forth. Hopefully, you learn a lot from reading this article!
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