The World's Simplest Electric Motor
Homopolar motor with rotating magnet
- 1 iron screw
- 1 alkali battery
- 1 piece bared copper cord
- 1 disc magnet of your choice (detailed information below)
- Connect the head of the screw with the disc magnet
- Connect the tip of the screw with the negative pole (lower side) of the battery.
- With the index finger, press the one bared side of the cord onto the positive pole (see photo below).
- Grab the cord with the other hand and touch the magnet with the free end of the cord on the outer side
Endless variations are possible. Here again, a ball K-19-C is brought into rotation. This is accomplished with a double tetrahedron made of connected rod magnets and steel spheres that rotates at an amazing speed.
- You can't get the magnet to rotate? The most important thing, naturally, is that the circuit is closed. Make sure that the tip of the screw is in direct contact with the underside of the battery. During your first attempts, use larger magnets - success is usually easier to achieve with these.
- The screw wobbles? You have probably used a screw with a crooked tip. File the tip until it is straight or try another screw.
- My rotating sculpture is too heavy; the magnetic pull is not strong enough to hold onto the battery. Connect the battery and screw with a small sphere magnet, for example the K-08-C (shown in the last photo above).
- Tip for the lesson [from our customer Michael Sexauer]: "It's particularly impressive, and also visible to those students sitting in the back row, when a paper pinwheel is attached to the magnets. You get an instant fan!"
Homopolar motor with rotating wire
- 1 S-15-08-N
- 1 normal AA battery
- 30 cm copper wire with 1mm diameter, 30 cm long for the wire loop
- a small bowl with approximately 1 cm of water (optional, to ensure contact)
1) First, form the circular portion of the wire loop by wrapping the wire around the magnet (one and a half wrappings). You can also use the battery to form the circular portion but you must be careful not to wrap too tightly or the loop won't fit over the somewhat larger magnet.