Academic journal article The Science Teacher

On-Off Motor

Academic journal article The Science Teacher

On-Off Motor

Article excerpt

... adapted from Magnetism #2Q by TOPS Learning Systems

1. Cut aluminum foil as big as an index card. Fold it in half three times lengthwise.

2. Paper-punch a hole in the middle. Cut the strip in half across this hole to make two "saddles."


3. Rubber-band each strip, as shown, to a size-D battery. Set a magnet between them.


4. Coil 8 cm of thin, bare wire around a Pencil 11/3 times. Adjust the arms so it spins easily when resting in the foil saddles.

5. Press the foil ends to the battery terminals. Give the coil a spin to kick-start your motor. Explain why it keeps spinning!


To build a motor that spins by turning on and off.


Copy the lab for each student or lab team.

Step 3. The magnet should cling to the battery. If not, use a bit of tape.

Step 4. Wire that circles 11/3 times yields a loop that is fairly evenly balanced. Natural spring in the loop prevents the bare wire from contacting itself and shorting out the coil.

Step 5. The tiny coil tends to spin in fits and starts, often reversing direction. A well-balanced coil may spin with impressive speed.


5. Electricity flows around the wire loop, creating associated electromagnetic poles perpendicular to the plane of the loop. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed


An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.