This dramatic experiment demonstrates expansion of air. Wet the mouth of a glass bottle and place a wet coin on it. Then warm your hands by rubbing and cup the bottle. After a while the air inside will expand. At that moment the coin will "lift" like the safety valve of a pressure cooker and let out the excess air.
http://www.arvindguptatoys.com/toys/expansion.html This work was supported by IUCAA and Tata Trust. This film was made by Ashok Rupner TATA Trust: Education is one of the key focus area
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