question_answer

  Give an experiment to show that sound needs a material medium for its propagation.                                             

Answer:

                                      Put an electric bell inside a closed glass   jar connected with a vacuum pump. Initially, air from the jar is not taken out.    Connect the electric bell with a battery as         shown in Figure. It rings and the sound        produced is heard by us.                  Now start evacuating the air from by the vacuum pump we will hear lesser sound, i.e., the loudness of the sound decreases. When there is no air in the glass jar, we do not hear any sound. This activity illustrates that sound waves require material medium (in this case             air) for its propagation.