Introduction to waves

 Waves are everywhere!! Waves come in many forms. There are mechanical waves, such as water waves, sound waves and earthquake waves. There are also electromagnetic waves, such as radio, television, microwaves, visible light, and x-rays.

Waves are propagation of a disturbance, usually with transfer of energy. 

Mechanical waves such as waves in the ocean and sound waves require a medium for propagation.  The medium for waves in the ocean is the water, and the medium for sound waves is air.  No medium is required for propagation of electromagnetic waves.

The simplest mechanical waves are propagated by periodic oscillation of the medium due to a disturbance.
 In transverse waves the direction of the deformation (in and out of the plane of the page in the animation) is perpendicular to the direction in which the wave travels (from left to right across the page).

In longitudinal waves the direction of the deformation (from left to right across the page in the animation)  is the same as the direction in which the wave travels.