Question

In the bell jar experiment, after starting the vacuum pump the sound gradually become fainter and finally we hear a feeble sound. Why?

• A. The Vacuum pump absorbs the sound
• B. The medium is sucked by the pump
• C. The bell jar behaves as isolated medium
• D. The bell do not produce such strong sound as it was producing earlier.

Answer 1

Answer: (B)

The medium is sucked by the pump

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 and so the sounds get fainter.