Spinning Monsters

Experiment with electromagnetism and create a homopolar motor.

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things you will need

  • 1 x AA battery
  • 3 x neodymium (rare earth) magnets
  • 30 cm copper wire (20 gauge)
  • Paper
  • Tape
  • Colouring pens
  • Scissors
  • 1 x grown-up (see safety notice)

safety notice

  • This project is aimed at ages 8+.
  • Adult supervision is highly recommended.
  • Neodymium magnets are extremely strong. Keep them out of reach of small children who may put them in their mouth. They are dangerous if swallowed.
  • Neodymium magnets can also interfere with electronic devices, so keep them away from phones and other screens.
  • Remove the magnets from the battery immediately after running the motor.
  • Only run the motor for a few seconds – the motor (battery and wire) will get hot.
  • If you notice the wire or battery getting hot, stop the motor immediately. Once the motor has cooled down, remove the magnets.
  • Do not reuse a battery after overheating.
1

Gather your materials

On a clean and dry table lay out the materials needed. 

2

Bend the wire

  • Bend the wire in half to make a narrow V shape.
  • Now bend the wire to form a rectangle shape – with 5cm sides.

Top tip

Try to keep the shape as symmetrical as possible. This will prevent the wire slipping off the battery when it spins.
3

Prepare the battery

  • Stack the neodymium magnets on top of each other.
  • Place the flat end (the negative (-) terminal) of the battery on top of the stacked magnets.
4

Make it spin

  • Place the V of the wire on top of the battery so that it connects with the positive (+) terminal.
  • Tweak the wire at the bottom so that the ends encircle (are either side of and almost touching) the stacked magnets. You may need to trim the wire at this point.
  • Let go and watch the wire spin.

Top tip

Make sure the shape is as symmetrical as possible. Make sure your wire is free to move around. If it’s too close to the magnets, it may get stuck and not move.
5

Create your monster

  • Once you have your motor working, take the wire off the battery.
  • Now, decorate the wire using the pens, tape and paper to create a monster motor of your choice.
  • Make sure to keep your design symmetrical, so it can still balance on the battery.
6

Time to experiment

Now, try some other shapes and sizes.

So, what is making your monsters spin?

The technical name for your spinning monsters are homopolar motors. A homopolar motor is a type of motor that demonstrates something called Lorentz Force. Lorentz Force occurs when electricity moves through a magnetic field.

In your monster motor, electricity is flowing through the copper wire from one terminal of the battery to the other. As electricity moves through the magnets attached to the negative terminal, it creates a force (Lorentz Force) that causes the wire to spin.

!

Top tip

Always remember to remove the battery from the magnet immediately after use and disconnect the wire.

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