This experiment has to do with refraction. You will need two coins and two glasses and water. Place a coin on the table and place the glass on top. In the second case place the coin inside the glass. Right now both coins will be visible. But when you pour water in the first glass the coin will disappear. But the coin in the second glass will still be visible despite the water. This happens because of the refraction of light.
http://arvindguptatoys.com/toys/Disappearingcoin.html This work was supported by IU
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