Question

Q. Take a metal or glass tumbler. Make sure that it is dry. Place a cell phone in it. Ask your
friend to give a ring on this cell phone from another cell phone. Listen to the ring
carefully. Now, surround the rim of the tumbler with your hands. Put your mouth on the
opening between your hands. Indicate to your friend to give a ring again. Listen to the
ring while sucking air from the tumbler.

Answer the following questions:
(i) Does the sound become fainter as you suck air?
(ii) Remove the tumbler from your mouth. Does the sound become loud again?
(iii) Is it possible that the decreasing amount of air in the tumbler had something to do
with decreasing loudness of the ring?
(iv) What do you conclude from this activity?
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Answer 1

Answer:

Does the sound become fainter as you suck air?

Ans : We observed that sound becomes fainter than earlier when we try to suck air. But When we remove tumbler from our mouth the sound again becomes loud.

Remove the tumbler from your mouth. Does the sound become loud again?

Ans : When we remove tumbler from our mouth the sound again becomes loud.

Is it possible that the decreasing amount of air in the tumbler had something to do

Ans : Indeed, if you had been able to suck all the air in the tumbler, the sound would stop completely. Actually, sound needs a medium to travel.

What do you conclude from this activity?

Ans : Activity concludes that sound needs a medium to travel.