Fields of Attraction: Magnets and Magnetism

Magnets are everywhere.  From the small decorative pictures on your refrigerator to the giant cranes that separate metals in junkyards, magnets are found in many places and come in many shapes and sizes. 

But just how does a magnet stick to your refrigerator door, or to the metal in the junk yard?  What is a magnet, and how does it work?

A magnet is simply anything that produces a magnetic field.  It is this invisible magnetic field which allows the magnet to “stick” to some types of metal, like iron and steel.  We often see the magnetic field of a magnet represented as lines leading from one end of the magnet (the North pole) to the opposite end of the magnet (the South pole). 

While these magnetic field lines are invisible, you can see them by putting small pieces of iron metal  (also called iron shavings or iron filings) on a white sheet of paper, and placing the magnet beneath the paper.  The pieces of iron will align themselves along the magnetic field lines!  If you can find some iron filings (which you may be able to get from a metal working shop), try this with a bar magnet (that is, one that is a straight bar or tube)!

Magnetic fields are created by the movement of electrically charged particles, such as electrons (one of the building blocks of the atom).  This movement of electrons can be a permanent quality that comes from the material the magnet is made from, like a refrigerator magnet.  These are therefore called permanent magnets.  This movement of electricity can also be induced using electricity.  Let’s say you have a piece of wire, and you connect it to a battery.  The battery will produce an electric current in the wire—that is, it will cause electrons to flow through the wire.  The movement of electrons through the wire will create a magnetic field around it.  Because this field has been induced by electricity and will stop once the battery is disconnected, it is called an electromagnet (this type of magnet will not be a magnet once disconnected from the battery). 

Since we know that the flow of electrons through a wire will create a magnetic field, and we know that this magnetic field is what causes some metal objects to stick to a magnet, we should be able to make our own magnet using a battery and wire, as in the previous example. 

TRY THIS!

Here’s what you’ll need:

1.       One 9-volt battery

2.       Three feet of thin copper wire

3.       Electrician’s tape (usually thick, black, stretchy tape)

4.       One three inch steel, galvanized nail (not stainless steel or aluminum)

5.       Several paper clips (metal ones, not plastic ones!)

Here’s what to do:

1.       Wrap the copper wire around the nail as tight as you can, at least 50 times.  Leave at least 4 inches of wire hanging off each end of the nail.

2.       Make a small hook at each end of the wire. 

3.       Use the hook at the head end of the nail to hang the wire onto the positive terminal of the battery.   The end of the wire should touch the inside bottom of the terminal.  Secure the wire firmly in place with electrician’s tape.

4.       Use the hook at the point end of the nail to hang the wire onto the negative terminal of the battery.  The end of the wire should touch the inside bottom of the terminal.  Secure the wire firmly in place with electrician’s tape.

5.       Hold onto the wires, and move your nail close to the paper clips.  The nail should now pick up the clips like a magnet! 

NOTE:   Use caution here, because the battery will get hot!! 

Did your magnet work well?  How many paper clips could you pick up? 

MAKE UP YOUR OWN EXPERIMENT!

Connect more than one battery together, and see how many paperclips you can pick up!  Just connect the head end of the nail to the positive terminal of one battery, and the point end of the nail to the negative terminal of the other battery.  Then cut a small piece of wire to connect the open terminals of the two batteries together.

Try using a 12-volt battery instead.  How many paper clips do you think your nail will be able to pick up?

Try using a longer nail, or a larger piece of steel. 


References for further reading:

1)      Magnet.  Wikipedia.  2014, Apr 26.  Retrieved 5-20-2014.  (http://en.wikipedia.org/wiki/Magnet)

2)      Magnetic Field.  Wikipedia.  2014, May 22.  Retrieved 5-22-2014.  (http://en.wikipedia.org/wiki/Magnetic_field)

3)      How Magnets Work.  HowMagnetsWork.com. Retrieved 5-21-14.  (http://www.howmagnetswork.com/)


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