(LIGHT)
Take three rectangular pieces of cardboard .Make them stand and parallel on a table using wooden supports. Make holes in them at exactly the same horizontal level. Keep a burning candle on the table, with its flame at the level of the hole in the first cardboard. Now keep your eye in front of the third cardboard and adjust the cardboards such that you can see the candle flame through the holes.
You will find that the flame can only be seen when the holes are exactly in a straight line. If you disturb one of the cardboards, you will no longer be able to see the candle flame.
These experiments verify that light travels in straight lines. This is known as rectilinear propagation of light.
(SOUND)
With the help of the vacuum pump when the air is removed from the bell jar gradually the sound gets feebler. When the entire air is removed from the bell jar and made vacuum , cannot hear the sound from the cell phone .From this we learnt that sound cannot travel though vacuum.
Comments
velumani
dharmapuri, India
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March 4, 2015 - 4:22am
the over all works is neat
seemajayadhas
nagercoil, India
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March 17, 2015 - 5:25am
good
kalaiselvi1963
nagercoil, India
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March 17, 2015 - 5:37am
excellent