Sangeetha Pulapaka

I assume you are referring to waves here. When a pebble is dropped in a still lake, this creates a wave. This is called a transverse wave. A wave is able to transmit energy from one place to another without moving any matter.

Transverse waves can also be made on a slinky. As shown in the diagram, the direction of the motion of the moving particles in a slinky travel at right angles to the direction of energy transfer

When a slinky is compressed it creates a compression wave. In this the moving particles move backwards and forwards in the same direction as the  energy transfer. These waves are also called as longitudinal waves.

Sound is a compression wave. All sounds are caused by vibrations. The figure above shows how a vibrating ruler creates compression and refraction waves in air. A compression wave is created when the ruler goes up, as the air particles above the ruler are compressed together. A refraction is created at the same time below the ruler since the air particles during that time are spread out. Similarly, when the ruler goes down, rarefaction is created on the top of the ruler, and a compression is created below the ruler. Each vibration of the ruler creates new compressions and rarefactions which replace the existing waves that are moving through the air.

A few other points to remember:

  1. The frequency of a sound wave is the number of compressions made in a second.
  2. High frequency vibrations produce a high pitch and low pitch vibrations cause a low pitch.

The wavelength in transverse waves is the distance between two corresponding points as shown below. The wave length in a sound wave is the distance between two compressions.