Build a DC Motor (Anna M & Anna T)

Procedure

1. To make the armature for the motor, wind the wire around the cardboard tube to make a coil like the one shown in the photo. Wind the ends of the wire around the loops on each side of the coil. Leave about 5 cm of wire free on each end.

2. Hold the coil on its edge. Sand the enamel from only the top half of each end of the wire. This acts like a commutator, except that it blocks the electric current instead of reversing it during half of each rotation.

3. Partially unfold the two paper clips from the middle. Make a hook in one end of each paper clip to hold the coil.

4. Place two disc magnets in the bottom of the cup, and place the other magnets on the outside of the bottom of the cup. The magnets should remain in place when the cup is turned upside down.

5. Tape the paper clips to the sides of the cup. The hooks should be at the same height, and should keep the coil from hitting the magnet.

6. Test your coil. Flick the top of the coil lightly with your finger. The coil should spin freely without wobbling or sliding to one side.

7. Make adjustments to the ends of the wire and the hooks until your coil spins freely.

8. Use the alligator clips to attach one wire to each paper clip.

9. Attach the free end of one wire to one terminal of the battery.

10. Connect the free end of the other wire to the second battery terminal, and give your coil a gentle spin. Record your observations.

11. Stop the coil, and give it a gentle spin in the opposite direction. Record your observations.

12. If the coil does not keep spinning, check the ends of the wire. Bare wire should touch the paper clips during half of the spin, and only enamel should touch the paper clips for the other half of the spin.

13. If you removed too much enamel, color half of the wire with a permanent marker.

14. Switch the connections to the battery, and repeat steps 10 and 11.

Questions

1. Did your motor always spin in the direction you started it? Explain.

2. Why was the motor affected by switching the battery connections?

3. Some electric cars run on solar power. Which part of your model would be replaced by the solar panels?

4. Some people claim that electric-powered cars produce less pollution than gasoline-powered cars do. Why might this be true?

5. List some reasons that electric cars are not ideal.

6. How could your model be used to help design a hairdryer?

7. Make a list of at least three other items that could be powered by an electric motor like the one you built.

Photos

• Photos of Engineering Project