Question

When can you say that the sound is propagating through a medium​

Answer 1

Answer:

When the vibrating object moves backwards, it creates a region of low pressure called rarefaction (R). As the object moves back and forth rapidly, a series of compressions and rarefactions is created in the air. These make the sound wave that propagates through the medium.

Answer 2

Answer:

When the vibrating object moves backwards, it creates a region of low pressure called rarefaction (R), as shown in Fig. 2. As the object moves back and forth rapidly, a series of compressions and rarefactions is created in the air. These make the sound wave that propagates through the medium.