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Let's Make It?
So, you want to float a sewing needle on water and turn it into a compass. It's not as hard as it sounds, but it can be a quite fun experiment. (Especially if there's kids around.
Things you will need:
1 - sewing needle.
1 - magnet.
1 - bowl of water.
1 - piece of tissue paper.
How to do it:
Take your needle and stroke it across the magnet to magnetize it. (Always stroke in the same direction, as if you were petting an animal.)
Now take your bowl of water and a piece of tissue paper about the size of a penny. Gently float the tissue paper on the water. You only have a few seconds before the paper becomes saturated and sinks. So you must quickly, but gently, place the needle on the tissue.
If magnetized correctly, the needle should almost immediately start to turn towards north and south. After the tissue sinks the needle should stay floating, until something causes it to break through the surface of the water.
How does it work:
Something called surface tension keeps the needle floating. But explaining surface tension is a whole different experiment. It's the molecules of water wanting to stay together. Surface tension causes rain to bead up on your newly waxed car. (Anyone who has ever played with mercury knows it's surface tension is very high.) You can learn more about Surface Tension HERE!