written by: Ricky
• edited by: Wendy Finn
• updated: 10/3/2012
Gone are the days of using stars to point us in the right direction. Today, GPS systems are everywhere including our cars and phones. However, it is still a fun experiment to build your own floating compass.
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We know that the earth has magnetic fileds and so you can use a magnet to find direction relative to our ground position. This is possible because two magnets interact in a peculiar way depending on their force fields. If a magnet is allowed to rotate freely under the influence of the earth’s magnetic field (provided there are no strong magnets in the immediate vicinity) then the magnet will always align in the north-south direction.
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Building your own Direction Finder
Piece of foam
Pair of scissors
Piece of paper bigger than the soup bowl, pen, pencil, tape etc
Rectangular piece of a small permanent magnet
Take the piece of foam and cut it in the shape of an arrow as shown in the adjacent diagram. Of course the shape does not matter much but it helps to give it the shape of a pointer.
Cut a small slot towards the back side of the foam piece good enough to fit the magnet tightly so that it does not slip out on its own as shown in figure below on the left hand side
Put the piece of paper on a flat table and fix it with tape so that it does not move.
Put the soup bowl in the center, fill it with water and place the piece of foam fitted with the magnet gently on the surface of the water.
You will notice that the arrow turns to a particular direction and stays there. Try moving it around and then leave it free, it will again point in the same direction.
Mark the paper in the direction in which the arrow is facing with a straight line in that direction. Also draw a perpendicular line to this line so that we have a cross or plus shaped symbol on the paper representing the four directions.
Try to remember what direction the sun rises in the morning (ask your Mom or Dad if you are having trouble remembering). The direction will certainly be one of the two directions of the line which you have drawn perpendicular to the magnet line.
Mark that direction as East on the paper and the other end of the line is West. When you look at the east with your back towards the west, the right hand side will be the South while left hand will be North.
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So you see that just by using a small magnet you could figure out the directions. If you have a small magnet which already has its ends marked as north and south you do not even need to complete step 7. This may be a very simple gadget but it really works. Maybe it will prove useful if your GPS ever breaks.