For Physics aficionados the different waves and their characteristics could be crystal clear but for others, the difference between mechanical and electromagnetic waves may not be so much easy to grasp. However, the two types of waves vary in several ways even though both of these propagate energy around us.
Mechanical Wave vs Electromagnetic Wave
The main difference between mechanical and electromagnetic waves is that mechanical waves cannot travel without a medium whereas electromagnetic waves can travel through a vacuum with the help of any medium.
Another stark difference between the two is that the distance traveled by mechanical waves depends upon the elasticity of the medium it uses whereas the characteristics of an electromagnetic wave depend upon acting magnetic and electric fields.
These two types of waves also vary in their speed. A mechanical wave travels much slower than an electrical wave which travels as fast as light. An example of a mechanical wave is a sound wave whereas a microwave and a radio wave are examples of electromagnetic waves.
Comparison Table Between Mechanical Wave and Electromagnetic Wave (in Tabular Form)
| Parameter of Comparison | Mechanical Waves | Electromagnetic Waves |
|---|---|---|
| Medium | Cannot travel without a medium | Can travel without a medium |
| Factors affecting | Elasticity and inertia | magnetic and electric fields |
| Speed | Travels with the speed of the medium | Travels at the speed of light |
| Types | Transverse and Longitudinal | Only Transverse |
| Examples | Sound waves, surface waves | Microwaves, Radio waves, etc. |
What is Mechanical Wave?
According to definitions, mechanical waves are waves that are the result of oscillating matter and their movement is what carries the wave forward. This also means that mechanical waves always require a medium to travel and cannot travel in a vacuum.
Therefore, a mechanical wave can harbor speed that is limited to the speed of the medium and can only move in the direction that the medium carries it. This kind of wave also requires an initial amount of energy to kick-start the motion.
A mechanical wave can be of three types, longitudinal, transverse, and surface waves. A longitudinal wave is formed when the particles of the medium oscillate parallel to the forward direction of the wave.
A transverse wave is formed when the particles of the wave vibrate perpendicular to the direction of movement while a surface wave is formed when the waves move at the interface of two media. An example of the surface wave is ripples in a water body.
What is Electromagnetic Wave?
Electromagnetic waves are the result of accelerating electrically charged particles that intern affects other particles around them. In an electromagnetic field, no particles are oscillating but the photons itself propagate and creates a wave. Electromagnetic fields are based on Maxwell’s four laws.
An electromagnetic field is a result of changing electric and magnetic fields whose direction point 90 degrees to each other. The directions of these fields are also perpendicular to the direction of propagation of the energy and the wave.
Since electromagnetic radiation consists of no particles and only oscillating electric and magnetic fields, they do not need any medium to propagate. They can thus travel through a vacuum. The speed of an electromagnetic wave is as fast as the speed of light. Electromagnetic waves are governed by the laws of quantum electrodynamics.
In other words, electromagnetic waves are made of photons, which are uncharged particles that can travel at the speed of light. These waves propagate energy, momentum, and angular momentum away from the source.
As these photons move away from its parent source, it no more requires a continuous supply of energy to keep it in motion and thus creates what is called the far-field. The field surrounding the parent charge that created the wave in the first place is called the near field.
Main Differences Between Mechanical Wave and Electromagnetic Wave
- The main difference between mechanical and electromagnetic waves is that mechanical waves cannot travel without a medium whereas electromagnetic waves can travel through a vacuum with the help of any medium.
- Another stark difference between the two is that the distance traveled by mechanical waves depends upon the elasticity of the medium it uses whereas the characteristics of an electromagnetic wave depend upon acting magnetic and electric fields.
- A mechanical wave travels much slower than an electromagnetic wave which travels as fast as light whose primary constituents are photons.
- An example of a mechanical wave is a sound wave whereas a microwave, a radio wave, infrared, ultraviolet rays, X-rays, Visible light, and gamma rays are examples of electromagnetic waves.
- Mechanical waves are waves that are the result of oscillating matter and their movement is what carries the wave forward whereas Electromagnetic waves are the result of accelerating electrically charged particles.
Conclusion
Both Mechanical and Electromagnetic waves are a source of propagating the energy from one place to another. Among the various types of waves in physics, these two are the most commonly found and discussed.
The main difference between mechanical and electromagnetic waves is that mechanical waves cannot travel without a medium and can harbor speed that is limited to the speed of the medium whereas electromagnetic waves can travel through a vacuum with the help of any medium and can travel at the speed of light.
Mechanical waves are waves that are the result of oscillating matter and this kind of wave also requires an initial amount of energy to kick-start the motion whereas electromagnetic waves are the result of accelerating electrically charged particles that intern affects other particles around them.
A mechanical wave can be of three types, longitudinal, transverse, and surface waves whereas an electromagnetic wave can only be a transverse wave. An example of a mechanical wave is ripples in a water body whereas those of an electromagnetic wave are microwaves, radio waves, and ultraviolet rays.
The distance traveled by mechanical waves depends upon the elasticity and inertia of the medium it uses whereas the characteristics of an electromagnetic wave depend upon acting magnetic and electric fields. A mechanical wave only propagates the energy within the particles whereas an electromagnetic field propagates energy, momentum, and angular momentum.
References
- https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.201900267
- https://www.astm.org/DIGITAL_LIBRARY/JOURNALS/GEOTECH/PAGES/GTJ10999J.htm