how is an electromanetic wave different fom a mechanical wave?

Answer 1

An electromagnetic wave is a wave which is capable of transmitting its energy through a vacuum (i.e., empty space). Electromagnetic waves are produced by the vibration of electrons within atoms on the Sun's surface. These waves subsequently travel through the vacuum of outer space, subsequently reaching Earth. Were it not for the ability of electromagnetic waves to travel to Earth, there would undoubtedly be no life on Earth. All light waves are examples of electromagnetic waves.

A mechanical wave is a wave which is not capable of transmitting its energy through a vacuum. Mechanical waves require a medium in order to transport their energy from one location to another. A sound wave is an example of a mechanical wave. Sound waves are incapable of traveling through a vacuum. Slinky waves, water waves, stadium waves, and telephone chord waves are other examples of mechanical waves; each requires some medium in order to exist. A slinky wave requires the coils of the slinky; a water wave requires water; a stadium wave requires fans in a stadium; and a telephone chord wave requires a telephone chord.

Answer 2

A mechanical wave is composed of particle motions. You can trace the displacement of elements of the medium carrying the wave. This is true for both transverse as well as pressure waves.

In an electromagnetic wave there is no supporting medium and no mechanical motion. An electromagnetic wave consists of electric and magnetic fields interacting with each other.