Question

How can you show that sound cannot travel through a vacuum?

Answer 1

take a bell jar and place an electric bell into it. Now put a cork on the mouth of the jar. Pass a glass tube through the cork into the jar. Connect this tube to a vaccum pump. Now start the bell. After sometime switch on the vaccum pump

OBSERVATIONS
at first when we start the bell then we are able to hear the sound of the bell but as soon we start the vaccum. pump the the sound starts lowering down. This shows that sound cannot propogate through vaccum