Question

An airtight bell jar is fitted with an electric bell.It is also connected to a vacuum pump. On starting the pump and the bell, the sound gradually becomes fainter and
finally stops. This experiment proves the fact that sound is a​

Answer 1

Answer:

Sound is a mechanical wave.

Explanation:

Mechanical waves require a medium for propagation.

Answer 2

Answer:

Sound needs a medium to travel.

The vacuum pump pumps out the air, and thus the medium through which the sound travels is pumped out.

So, the sounds gets fainted

Bell Jar Experiment : Let us take a bell jar and suspend an electric bell in it and connect it to a battery outside the jar When the circuit is closed (switch is on) we can hear the bell ringing as the jar contains air and sound travels through this air

We then remove the air from the jar with the help of a vacuum pump connected to the bell jar Now as we close the circuit we can hardly hear any sound even though the hammer of the bell is seen striking the gong So we can conclude that sound cannot propagate in the absence of the material medium

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