Electromagnet

Objective

The objective of this experiment is to further demonstrate the relationship between electricity and magnetism. We will show how to use electricity to magnetize metal.

Materials Required

Several feet of insulated wire
6-Volt Battery
A nail (or a bolt)
Permanent Magnet
Small metal objects (e.g., thumbtacks, paper clips, etc.)

How to Build It

Begin at one end of the nail and wrap the wire in small loops around the nail. The loops should be tight around the nail.

Experiment

Attach the ends of the wire to the terminals of the battery. Touch the end of the nail to one of the metal objects. The object should stick to the nail. See how many objects you can pick up.

Now try wrapping more wire back over the loops previously made. The wire should still wrap around the nail the same way as before. Attach it the battery again and see how many objects you can pick up now.

Now let us determine which side of the electromagnet is north and which is south. Bring the north side of the permanent magnet (PM) to one end of the nail. Does the electromagnet repel or attract the PM? If the electromagnet repels the permanent magnet, then it is the north side of the electromagnet; if the electromagnet attracts the PM, then it is the south side. Just as opposite charges attract, so do opposite poles.

electromagnet picture

Troubleshooting

If your electromagnet does not seem to be working, try the following:

  1. Check the wire connections to your battery.
  2. Try making more loops around the nail.
  3. Try picking up smaller objects.
  4. Try a different nail or bolt.
Questions for Thought
  1. Why did the magnetic field increase when you wrapped the wire back the other way?
    ANSWER: The magnetic field increased because you increased the number of coils, and thus, the strength of the field. As long as you wrap it in the same direction, the field will continue to increase with each additional coil.
  2. What would happen if you wrapped the wire around a plastic or wooden object instead of a metal nail? Why?
    ANSWER: There would still be some magnetic field but not as much. The wood or plastic would not actually affect the field, they would simply be taking up space. With a metal core, especially with iron, the field is strengthened. Basically, with the nail inside, instead of the plastic or wood, you can pick up many more objects.

Additional Information

This experiment is contained in nearly every book which deals with electricity.


ASU Department of Electrical Engineering
Last Updated: June 21, 2002
Original Page Development by: Matt Dayley and Keith Holbert
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