Make your own DC electric motor

Materials:

D-cell, disk magnet, rubber band, 2 large paperclips,scissors, sand paper, 2-3 feet thin wire, nail

Procedure:

  1. Take the 2-3 foot piece of thin wire andwrap it

around the D-cell. The total number ofwraps

dependson thegauge (“thinkness”) of the wire.

  1. “Tie” the ends of the wire through the loops

so that the loop of wire will remain in place

when you let go. Make sure they are 180°

apart along a diameter of the loop. It is very

important for the loop to be “balanced.” Try

to spin it freely between your fingers.

  1. Bend the paper clips in orderto form loops on their ends,

which will be used for holdingthe wire loop. They should

look like the ends of safety pins.

  1. Secure these to the dry cell with the rubber band. Place the

magnet on the dry celland place the wire loop in its

holders. Observe what happens.

  1. Disappointed that nothing happened? The reason is that the wire is insulated with paint, which must be scraped off. This is the trickiest part. Whether or not the ends of the wire loop are scraped correctly will determine thesuccess of your motor.
  1. Hold the wire loop vertically between yourthumb and

Indexfinger of one hand nearthe edge of the table

(desk) so that thewire end lies on the table.

  1. Use the other hand and thesand paper to scrape theinsulationoff the top half of the wire. If you scrape too much, use a permanent marker to “repaint” the insulation.
  1. Turn the wire loop around and scrape the top half of the wire on the other end.
  1. Place the wire loop into its holders and move the loop so that it lies just above the magnet. The motor should now begin spinning. If not, you may need to give it a little push to get it going. A nicely balanced loop and proper scraping are essential to the performance of this motor.

Other instructions and pictures of electric motors made

insimilar ways may be found on the World Wide Web at:

Extension:

Why is it necessary to scrape only the top half of each wire?

Observe the direction your motor spins. Turn the magnet over and observe again. What do you notice?

Draw a diagram using the rule for force on a current bearing wire or moving charge when in the presence of a magnetic field in order to explain why this motor works.

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