MATERIAL REQUIREDS
A glass tumbler, water, postcard
THEORY
The force per unit area is called pressure. The pressure exerted by atmosphere is called atmospheric pressure. The atmosphere exerts pressure about 1.013 ✖ 10 5 N/m-2 or 760 mm of Hg at Sea level. Atmospheric pressure can hold about 10 m high water column.
PROCEDURE
- Take a glass filled with water and cover it with a postcard.
- Invert the glass tumbler supporting the postcard against the glass with your palm.
- Now, hold the glass with your hand and remove the supporting palm slowly.
OBSERVATION
You will find that the water does not fall down.
RESULT
Atmospheric pressure exerted on the postcard hold the water in tumbler.
CONCLUSION
This activity confirms that the atmosphere exerts pressure on a body from its all sides.
PRECAUTION
- Apparatus should be handled with care.
- Postcard should not be too thick or too thin.
- Water should be filled enough up to the rim of tumbler.
- Air bubble must be avoided between postcard and water.