Thursday, June 19, 2008

A bigger motor

Our next motor is simply a larger version of the first one, with a base made of wood like this:
In the middle of the base we have placed the magnet. Around the magnet we have drilled four small holes for the support wires.
We wind the coil using thick wire (this wire is 20 gauge enameled copper wire). We use a "D" cell as the coil form:
We use brass wire for the supports, and we make all the connections under the base, so everything looks nice and neat. For a battery connection, we use a 9 volt battery clip.
The finished motor looks like this:
How does it work?
When electricity flows through a coil of wire, the coil becomes an electromagnet. An electromagnet acts just like a regular magnet. It has a north pole and a south pole, and can attract and repel other magnets.
Our coil becomes an electromagnet when the bare copper half of the armature wires touch the bare wire of the supports, and electricity flows into the coil. The electromagnet has a north pole which is attracted to the south pole of the regular magnet. It also has a south pole that is repelled by the south pole of the regular magnet.
When we scraped off the insulation from the armature wires, we were careful to do it with the coil standing up, and not lying flat on the table. This makes the poles of the electromagnet point to the left and right (as if there was an invisible regular magnet that had the wire wrapped around it). If the coil was flat on the table, the poles would point up and down. Since the poles point left and right, they have to move in order to line up with the magnet at the bottom, whose poles are aligned up and down. So the coil rotates to line up with the magnet. But once the coil is exactly lined up with the magnet, the insulated half of the wire is now touching the supports instead of the bare half. The electricity is cut off, and the coil is no longer an electromagnet. This leaves it free to coast on around until the bare copper can again touch the bare support, and start the whole process over again

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