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See for yourself how the forces of electricity and magnetism can work together by building a motor using simple materials! Electricity and magnetism are both forces caused by the movement of tiny charged particles that make up atoms, the building blocks of all matter. When a wire is hooked up to a battery, negatively charged electrons flow away from the negative terminal of the battery toward the positive end, because opposite charges attract each other, while like (similar) charges repel each other. This flow of electrons through wire is electric current, and it produces a magnetic force.
In a magnet, atoms are lined up so that the negatively charged electrons are all spinning in the same direction. Like electric current, the movement of the electrons creates magnetic force. The area around the magnet where the force is active is called a magnetic field. Metal objects and other magnets that enter this field will be pulled toward the magnet.
The way the atoms are lined up creates two different poles in the magnet, a north pole and a south pole. As with electrical charges, opposite poles attract each other, while like poles repel each other. Learn about electromagnetism and its many uses here.
Now let's watch it work as we build a motor. (Note: This project requires adult supervision.)>> Check out the project video to see the motor in action!
The armature is a temporary magnet, getting its force from the electrical current in the battery. The neodymium magnet is permanent, meaning that it will always have two poles, and cannot lose its force. These two forces - electricity and magnetism - work together to spin the motor. The poles of the permanent magnet repel the poles of the temporary magnet, causing the armature to rotate one-half turn. After a half-turn, the insulated side of the wire (the part you colored with permanent marker) contacts the paperclips, stopping the electric current. The force of gravity finishes the turn of the armature until the bare side is touching again and the process starts over.
The motor you created uses direct current, or DC, to rotate the armature. The magnetic force is only able to flow in one direction, so the motor spins in only one direction. AC, or alternating current, uses the same principle of electron flow, but the pole is rotating rather than in one place. AC motors are often more complex than DC motors, like the simple one you were able to make. Unlike a fixed DC motor, AC motors can switch the direction of rotation. (The DC motor you made is only able to spin in one direction because its direction is determined by the poles of the permanent magnet. If you turn the magnet over, so the other pole is facing up, it will change the direction the motor spins.)
When you held the second magnet over the top of the armature, it either stopped or made the motor rotate more rapidly. If it stopped, it's because the pole was in the opposite direction of the first magnet, in a sense canceling out the rotation of the armature. If it moves faster, the same poles of the first and second magnets, which repel each other, work to spin the armature more quickly than with only one magnet.
Building Bigger, Faster Motors
Experiment with batteries of higher voltage, as well as more powerful magnets. You can also try using ceramic magnets. One design we found worked well was to set the armature over 4 ceramic ring magnets and connect the supporting paperclips to a 6V battery. You can also try increasing the size of the armature, and how many coils there are, to make a stronger electromagnet. When using batteries of higher voltage, and bare wires, be very careful. The circuit can emit enough heat to cause a burn if the wire is held too long.
Science Project Video - Build a Simple Motor
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