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Build a Mono Polar Motor


  • One shake magnetic charger torch
  • Short length of copper wire
  • Two torch battery cells
  • One short screw

Batteries, copper wire, short screw


Unscrew the torch and remove the rare earth cylindrical magnet inside.

Position the flat end of the screw as close to the centre of the magnet as you can

Remove the rare

Touch the tip of the screw to the bottom, negative, side of one of the cells. It will stick.

Tip of screw in place

Stack the second cell on top so as to give you three volts of electricity.

(With a strong magnet you might get away with one torch cell)

Now connect the one tip of the copper conducting wire to the top.

Positive-side of the one cell and rub the other end of the wire against the magne.

Don’t rub the tip of the wire, let it slide along the magnet.

The magnet and the screw will start spinning rapidly.

The Science

Although the exact principle of the mono polar motor is quite complicated it still follows the rules for all electric motors. A magnetic field plus an electric current through a conductor results in motion.

Prof. Pink's Notes

The Mono Polar Motor is one of the smallest electric motors you can build. It will spin up to 8000 revs per minute. But yours will come flying of long before it reaches that speed because it is just about impossible to centre the screw accurately on the magnet. The result is the spinning magnets become unbalanced and flies of into space.