Another easy-to-make diy science project. Build a compass for [almost] free! (1/14/2008)
Update: Using needles is not a good idea. Please skip this project and read how to make a compass using a paperclip.
A compass can locate the magnetic north pole, not the physical North Pole. The operation is simple; a magnetized needle always aligns to the earth's magnetic field, so any needle or magnet can be used to build a compass.
Here is what we need to build a home-made compass:
First, we need to make a magnet. We can't use the big one because is too heavy.
... Well, yes, you can use a neodymium magnet to make a compass but this time we are making one using needles.
So, to magnetize a needle, just rub the needle to the magnet as the right image shows. You need to make circular movements. Repeat the cycle about 30 or 40 times.
Next, put the neddle in the cork as the photo shows. You may need to use pliers.
*** Needles are dangerous! You can get hurt handling needles improperly. Don't try to push the needles with your hand. This project needs adult supervision and authorization. Please read the Disclaimer.
Put the second needle into the cork as the photo shows and drop it into the plate with water. You may need to adjust the second needle or the water until the tip touches the plate. The second needle tip will be the base or "axis" of the homemade compass.
After a few seconds, the cork will move and align to the North Pole. Wind can interfere with the compass, so this project needs to be done in a place where wind or movement is not a problem.
Here is the homemade compass and a "made in Japan" compass. As you can see, both are pointing north.
Basically, the needle is a small magnet because it was rubbed on the big magnet. So, when we put the needle in the cork, there is little friction that allows the magnetized needle to align to the magnetic field of the earth.
As I did mention before, the compass points to the magnetic north pole. The physical North Pole is close but not exactly at the same place. Sorry kids, this homemade compass is not going to indicate exactly where Santa Claus lives.
The left image shows the earth's magnetic field. It is always vertical on any place of the world, so doesn't matter where you are. The compass will point north; Always.
Please I do apologize but my drawing is not at scale. Also, ignore the call for help from mother earth as many countries do. [Unless you are decided to do something about it.]
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