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Have you ever used a magnet to pick up paperclips or made the dial of a compass spin or seen how one end of a magnet attracts an end of another magnet, but repels the other? You might be surprised to find that magnets and electromagnets are used all around us since every electric motor, generator or transformer requires a magnetic field for its operation. Sometimes, magnets are mounted on large cranes and used to move large metal objects. It is the unique properties of magnets that help your radio, telephone and most other electrical appliances work all around your home.

In 700 BC, the Greeks found that a kind of rock stuck to iron. Later, the Chinese used pieces of this kind of rock (called magnetite) to build the first magnetic compasses to guide their ships -- about 800 years before anyone in Europe thought of using magnets for navigation.

It wasn’t until the early 1800s that electromagnetism was discovered, and in 1820, physicist Michael Faraday discovered how an electromagnet could be used to create a simple electric motor – the basis for all electric motors today.

This month, we’ll be making a simple electromagnet and considering how it differs from a permanent magnet; the kind made from the same material the Greeks discovered nearly 3000 years ago.

Concept:

Many magnets, like the ones holding your favorite pictures on your refrigerator, are called permanent magnets.  That’s because permanent magnets are always magnetic (although they can lose some of their magnetic power over time).  Magnets like the one in this experiment, however, can be turned on and off.  They are called electromagnets and run on electricity.  The electricity flowing through the wires of a copper coil forces the atoms in the nail to line up in the same direction.  This magnetizes the nail and it is then attracted to certain metals. 

Note:  Be careful.  The wires and/or battery might get very hot because of the speed of the fast moving electrons.  NEVER get the wires of your electromagnet near a household electrical outlet.

Objective:

To use electricity to organize atoms in a piece of iron to make a magnet.

Materials:  

1. A large nail or screw (do not use one that is galvanized or made of a different material, like aluminum)

2. 3 feet of insulated copper wire (you can buy this at any hardware store)

3. A six or nine volt battery

4. Small paperclips

5. A rubber band or masking tape
    

Procedure:

1. Take your wire and coil it tightly and neatly around the screw or nail.

2. Leave about 6” of wire free on each end and carefully remove about 1” of plastic coating from both ends of the wire. Attach one wire to the end of the battery and the other wire to the other end of the battery. Wrap a rubber band or tape around the battery to hold the wires tightly to the battery ends. Be careful, the wire can get very hot!

3. Once the battery is connected, the electricity runs through the wires of the coil forcing the atoms in the nail or screw to line up in the same direction. The nail or screw is now magnetic! Pick up your paperclips with your magnet! Unhook the battery and the nail or screw loses its magnetic power.

Questions:

1. Does changing the thickness or length of the nail affect the electromagnet’s strength?

The size of the nail has very little effect on the strength of your magnet. The number of wire coils and the power of the battery have a much greater influence on the power of your electromagnet. 

2. Does the number of coils you have on the nail affect your experiment in any way?

Since the number of coils determines the strength of your magnet (delivering more electricity to line up the electrons in your iron nail), it makes a great deal of difference in the power of your magnet to pick things up. In an electric motor, the more “windings” of copper wire in the motor, the more powerful it is to run the appliance.

3. What kind of tasks would be done better using an electromagnet, instead of a permanent magnet?

Since an electromagnet can be turned on and off, using one to lift heavy metal objects allows the machine operator to turn it on to pick things up, and turn it off to release the objects when they are placed. In an electric motor, current to the electromagnet is turned on to make the motor turn, and turned off to turn the motor off.

1. Wind fewer coils around the screw nail – can you pick up a greater or fewer number of paperclips?

2. Use a larger or smaller voltage battery – how does this affect the strength of your electromagnet?

3. Try placing a compass near your electromagnet – what happens to the hands of the compass when you attach the wires to the battery or when you turn off your electromagnet by disconnecting one of the wires

Magnetoids: They're just too cool!

If you enjoyed this experiment, check out our Magnetoids! You’ll learn about the unique property of every magnet to have a positive pole and a negative pole, and because of the unique alignment of their electrons, how magnets are always striving to stay in balance between attraction and repulsion forces. (product P8-1150)

Go there now!

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