Magnetism - Make Your Own Kind of Magnet
Electromagnets are another type of magnet. Electromagnets are usually iron-containing materials that have a magnetic force only when an electric field is flowing through them, you will learn more about fields as you continue this unit. The force that electromagnets have is called electromagnetism.
You're the scientist!
You can make your own electromagnet by following the directions below.
- Insulated wire (Light wire is easiest to wind into a coil. You need to remove the insulation from the ends that make electrical contact.)
- Battery (A lantern battery works best for this activity. It is easy to connect the wires to it and it is a stronger source of electricity than smaller batteries.)
- Clothes hanger (the type with the paper tube across the bottom).
- Large iron or steel nail
- An on/off switch is optional, but helps keep your battery from running down rapidly
- Paper clip or some iron filings to test your electromagnet.
- Remove the paper tube from the bottom of the hanger.
- Cut a short piece of wire, and remove the insulation from both ends.
- Connect one bare metal end to the battery and the other bare metal end to one side of the switch. Be sure the metal of the wire, not the insulated material, is touching the connector.
- Remove the insulation from both ends of the wire you have left. This should be a very LONG piece of wire. Be careful not to get it tangled. Connect one bare metal end of this wire to the other side of the switch. Be sure the switch is in the OFF position.
- Leave one foot or so of remaining wire to connect to the other side of the battery. If you start winding the coil immediately at the end of the wire, there will be no wire to connect it to the battery.
- Closely wind about twenty turns of wire around the paper tube from the hanger. This wire must have the insulation on it.
- Now, connect the other bare metal end of the wire to the other side of the battery and turn on the switch. Do you think it will pick up iron filings now? Try it and see.
- Turn off the electricity. Slide the nail into the center of the paper tube. Do you think this will have any effect on the electromagnet's strength? Try it and see.
- Remove your nail from the paper tube. Remember that it was not magnetic to begin with? Is it magnetic now? If it is magnetic, how did it become magnetic?
If you have more than one battery, you can try making the electricity stronger.
- Strip the insulation from both ends of a wire.
- Connect the connector at the side of one battery to the connector in the center of another battery.
- Then, connect your electromagnet to one side of one battery, and the wire going to your switch to the opposite side of the other battery.
Do you think this will make your electromagnet stronger? Try it and see. Try it with and without the nail in the paper tube.
- Disconnect the electromagnet from the battery.
- Wind another twenty turns of wire around the paper core.
- Try to put the wire turns right next to each other, and be as neat as you can.
- Test your electromagnet the same as you did before.
- Connect it to the battery, turn it on, and see how many iron filings it picks up.
- Put the nail in and see if this makes any difference. Connect another battery if you have one and test the electromagnet with and without the nail in the paper core.
- Now, disconnect the electromagnet, wind another twenty turns onto the coil, and do it all over again.
Design your own experiment using the electromagnet that you made. Be sure to make a hypothesis and record your observations and conclusions.
Write about it!
- Which makes the electromagnet most powerful? How it is related to the number of turns of wire? How does having more electricity affect it? What changes when you have the iron core in the center of the coil?
- How are permanent magnets and electromagnets alike?
- How are permanent magnets and electromagnets different?
Electricity and magnetism are closely related. When electricity flows through a pathway, it is called a complete circuit. When the electricity is moving through the circuit, a magnetic field is generated around the wire. This kind of magnet only stays magnetized as long as the electricity is flowing through the circuit. This can be very handy. Can you think of some situations where it would be useful to be able to turn off a magnet?
When you turn off the electricity flowing to an electromagnet, the magnetism is also turned off. This is a very useful property. You can use an electromagnet to pick up a piece of iron and then drop it someplace else. This property is used in junk yards. They use huge electromagnets and a crane to pick up, move, and drop old, junked cars.