Heart-shaped Homopolar Motor

Show Your Physics Love … build your own heart-shaped homopolar motor!

 

[No dialogue or sound track, just white noise. Upclose video of a small heart made from a paperclip, balancing on an AA battery and some magnets and rotating. A small stress ball cow toy sitting beside it. A small Happy Valentine's Day sign in the background.]

 

Materials

 

  • One to three neodymium disc magnets, at least 15 mm in diameter (same or slightly larger than the diameter of an AA battery)
  • One AA battery
  • Bare copper wire, about 18 gauge or so, about 25 cm long

 

Assembly

 

  1. Stand the battery up on the stack of magnets and make sure the surface you are working on is flat and smooth.
    Diagram of a AA battery standing upright, negative side down on a small stack of three flat round magnets with positive end up and indicated.
  2. Find the centre of your wire and bend it here. This is the centre of the top of the heart or the point at which the heart will sit on top of the positive terminal of the battery.
    Diagram of wire bent into a heart shape.
  3. This is the trickiest part! You need to form two semi-circles of wire at the bottom of the heart – one semicircle from each side of the loop. The wire can not touch any other part of the wire or you will short out your circuit. These semicircles should fit as snuggly as possible around the magnets, so use a piece of paper to trace around the magnet to give you a visual guide when bending your wire. Also, the distance from the dip at the top of the heart (where it sits on the positive terminal) to these semicircles needs to be about 5 to 5.5 cm. The semicircles need to make (and keep) contact with the magnets, so measure this distance along the battery to check your dimensions.

    Diagram outlining the instructions above indicating the size of the heart-shaped wire and the direction of the base.
  4. There will be a lot of trial and error to get your shape to fit properly – don’t give up!! The end-product looks something like this:

    Image of finished heart motor with heart-shaped wire on battery.