Either that or someone who finds practical physics fascinating.
The challenge is to make a motor using just:
- A battery
- A magnet
- A screw
- 1 piece of wire
How It Works
When you touch the wire to the side of the magnet, you complete an electric circuit. Current flows out of the battery, down the screw, sideways through the magnet to the wire, and through the wire to the other end of the battery. The magnetic field from the magnet is oriented through its flat faces, so it is parallel to the magnet's axis of symmetry. Electric current flows through the magnet (on average) in the direction from the center of the magnet to the edge, so it flows at right angles to the magnetic field. When you have an electric current at right angles to a magnetic field you produce a foce at right angles to both. THis force makes the magnet (and therefore the screw too) turn.
It doesn't have to be a screw - any piece of metal that won't be squashed between the magnet and battery will work, it's just easier to see a screw turn.