World’s Simplest DC Motor

Build a simple homopolar motor with a battery, a magnet and a strip of copper wire


  • AA battery
  • Neodymium Magnet
  • Copper or Aluminum (wire)


  • Shape the wire so that it will balance evenly on the the positive end of the battery and spin around it
    • there are a number of ways to do this (please refer to the pictures on this page)
    • you’ll want to start the initial bend in the middle of the wire so both ends of the wire are approximately the same length (and weight).
  • Stack the battery on the magnet so the positive end of the battery is facing up.
  • Carefully arrange the wire so that it rests on the tip of the positive end of the battery and the bottom lightly touches the magnet at the bottom.
  • TIP: the longer the wire the less heat the electricity the electricity will generate in the wire.

Observation and Results:

  • The wire shape you created should spin around the battery.
  • What did you observe?
  • What do you think is happening?


When electricity passes through a wire, it generates a magnetic field. This is the basis for all electrical motors. The current passes through a completed circuit in this setup because the wire is touching the positive terminal and the negative terminal. The magnetic field generated by the current passing through the wire interacts with the magnetic field of the magnet at the bottom of the battery and this is what drives the motor.

Homo Polar Motor Pictures


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Coco Science

Coco is interested in STEAM with a particular interest in the A. She has a hamster named Marshmallow and likes to read, craft, cook and dance.