Monday, 10 September 2012

Make your own simple motor

This is a great project and there are so many things you can do with this project to learn about the relationship between electricity and magnets.  This is the simplest motor you can make that I've seen out there and it's a lot of fun to make so what you will need?

Before starting this project please be careful when using rare earth magnets they are very strong.  They can be dangerous: if they are swallowed fatal.  RARE-EARTH MAGNETS SHOULD BE KEPT OUT OF REACH OF CHILDREN. RARE-EARTH MAGNETS ARE NOT TOYS. Children should not be allowed to handle or play with rare-earth magnets. Children and adults should not ingest magnets or place magnets in any body orifice such the ear, nose or mouth. Ingestion of magnets is very hazardous. If magnets are ingested or aspirated to the lungs, immediate medical attention is required.  More information on the safety of rare earth magnets

When doing this project we were very careful and if you are you can have fun like we did so... Now for the fun!
  • 2.00mm copper wire
  • A decent AA battery
  • 2 rare earth magnets about 10mm size
  • Wire cutters
  • Sandpaper, wire strippers or scissors
Now here is what you need to do...

Cut a piece of the copper wire that is 37cm long. 

 

First you make a shape like this...


or this...






Put the two magnets at the negative end of the battery (be careful when putting two rare earth magnets together though, as they can pinch the skin which can be painful) and then carefully place the copper wire so that one end is touching the postive of the battery and the other is touching the magnet underneath.

If you use insulated or enamelled wire, you will have to make sure you strip the outer coating where the wire touches the battery and the magnet, you can use wire strippers, sandpaper or a pair of scissors to do this.

Then this should happen...

 
One question you could ask your child, or the children you are doing this science project with is: is it possible to make the wire rotate the other way.  This video I've made, obviously, gives you the answer.
 
Other questions you could ask when doing this project is:
 
  1. What happens when you change the thickness of the wire?  You could even go as far as to try different thicknesses. 4mm or 1mm for example.
  2. What happens if you try and spin the wire in the opposite direction?
  3. Can you change the speed of the motor?  You can talk about what factors affect the way the speed of the motor.  You may like this link.
This project does wear the battery out quite quickly, so use fresh batteries every time for best results. You also should becareful when handling your motor as the wire can get hot very quickly.

Why does it work?

In our motor we have the copper wire which is a really good conductor of electricity, the copper wire then becomes an electromagnet when the circuit is made.

Then there are the two permanent magnets. They make a steady magnetic field so that the copper wire will turn when a current flows in it.

The we connect the copper wire to a battery and it connects to the magnet, this is when we switch the motor on; the current then starts to flow and this is the moment that the copper wire becomes an electromagnet.

You only want the copper wire to be just touching the permanant magnets because then there is no turning force on it.  This means that the electromagnet, the copper wire, will be lined up with the permanent magnets.  If the current in the copper wire were constant, the copper wire would stop in this position. The reason it spins and keeps spinning is the break in the circuit as the copper wire gently bounces around the permanant magnets, so the current stops for an instant.  The momentum of the copper wire spinning is what keeps going and the contact with the magnet reconnects the circuit.
 
Turn the battery around and you change the poles of the electromagnet and this is what makes it spin the other way round.

I believe that this is all correct, however, if you are specialist in this field then please let me know and I am always willing to update posts with any necessary corrections.

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