Waves come in many shapes and forms. While all waves share some basic characteristic properties and behaviors, some waves can be distinguished from others based on some observable (and some non-observable) characteristics. It is common to categorize waves based on these distinguishing characteristics.
One way to categorize waves is on the basis of the direction of movement of the individual particles of the medium relative to the direction that the waves travel. Categorizing waves on this basis leads to three notable types of waves:
- Transverse waves: Transverse waves have particle movement that is perpendicular to the direction of energy propagation.
- Longitudinal waves: Longitudinal waves are mechanical waves in which particles within the medium oscillate back and forth in a direction parallel to that of the wave propagation.
- Surface waves: Surface waves are mechanical waves that are a combination of both longitudinal and transverse waves. Surface waves, like the name suggests, travel across the surface of a medium or at boundaries between them.
Another way to categorize waves is on the basis of their ability or inability to transmit energy through a vacuum (i.e., empty space). Categorizing waves on this basis leads to two fundamental types of waves:
- Electromagnetic waves
- Mechanical waves
What is a mechanical wave?
Amechanical waveis a wave that 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 medium is simply matter or material such as air, water, or solid earth.
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 jump rope 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 jump rope wave requires a jump rope.
It is important to know that although mechanical waves require a medium in order to transfer energy, it is just the energy that travels. The matter itself does not change location. For example, it may look as if the water in an ocean wave is being carried to the shore by the wave. In reality though, the water moves around in a circle without changing its actual location. Imagine a ball floating on the water. It isn’t carried to shore by the waves, but rides in circles on top of the waves just like the water beneath it.
What is an electromagnetic wave?
Anelectromagnetic waveis a wave that is capable of transmitting its energy through a vacuum (i.e., empty space). Electromagnetic waves are produced by the vibration of charged particles. Following are the different types of electromagnetic waves:
- Radio waves
- Ultraviolet waves
- Gamma rays
- Radio waves
- Light waves
Electromagnetic waves are emitted by electrically charged particles undergoing acceleration, and these waves can subsequently interact with other charged particles, exerting force on them.
Electromagnetic waves carry energy, momentum and angular momentum away from their source particle and can impart those quantities to matter with which they interact.
Electromagnetic waves that are produced on the sun subsequently travel to Earth through the vacuum of outer space. Were it not for the ability of electromagnetic waves to travel to through a vacuum, there would undoubtedly be no life on Earth. All light waves are examples of electromagnetic waves.
Mechanical Waves vs Electromagnetic Waves
|BASIS OF COMPARISON||MECHANICAL WAVES||ELECTROMAGNETIC WAVES|
|Medium||Mechanical require a material medium for their propagation.||Electromagnetic waves do not require a material medium for their propagation.|
|Formation||Mechanical waves are formed due to vibrations of the particles of the medium. These vibrations can be along the direction of propagation of wave or perpendicular to it.||Mechanical waves are formed due to varying electric and magnetic fields.|
|Speed||These waves have a low speed i.e speed of sound in air is 332 m/s at 0oC.||These waves travel with a very high speed of 3×108 m/s through vacuum.|
|Frequency & Wavelength||These waves usually have low frequency and large wavelength.||These waves usually have high frequency and low wavelength.|
|Nature||These waves can be transverse or longitudinal.||These waves are only transverse waves.|
|Vacuum||They cannot travel in vacuum. They need a material medium for their propagation.||They can travel in vacuum.|
|Polarization||They can be polarized only when they are transverse. When they are longitudinal, they cannot be polarized.||They can be polarized.|
|Examples||Sound waves, Pressure waves, Slinky waves, water waves, stadium waves, spring waves, Seismic waves, jump rope waves etc.||Microwaves, X-ray, Radio waves, ultraviolet waves, light waves etc.|