One Loop Motor in 3 Pieces

Wire, magnet, battery - and the motor is ready
Author: Duijnstee, Rotterdam, Netherlands
Maarten Duijnstee, Physics Professor from Rotterdam, sent us an instructional experiment with a very simple electromagnetic motor and writes:
The one loop motor is one of my favourite SuperMagnet-experiments. No soldering necessary, and the rotor can be formed out of a single piece of copper wire. Even children as young as 8 can make it.


  • 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)
Tip: The copper wire can be made from a normal electrical cable with the isolation removed.
The finished loop and battery with the magnet


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.
2) Bend the remainder of the wire into the shape shown in the photo. Then form the loop spike on which the battery will be placed.
The dimensions of the finished loop: 6 cm tall, 4,5 cm wide.
3) Place the magnet on the negative pole of the battery. If necessary you can make a small dent in the positive pole of the battery so that the spike can be better centered on it.
The circular part of the wire form must be able to move without hindrance around the magnet but must nevertheless stay in contact with it in order to close the electrical circuit.
If necessary to ensure contact, place the whole system into the bowl of water.

Physical background

The one loop motor is a nice experiment to demonstrate the so-called Lorentz force. This occurs when an electrically charged conductor is placed in a magnetic field. The direction in which the motor turns indicates where the north and south poles of the magnet are to be found.

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