Key difference - sound waves vs. electromagnetic waves
In the modern world, there are many scientific and technological uses of various types of waves. Most of these applications use sound waves or electromagnetic waves. Sound waves are mechanical waves while electromagnetic waves are not mechanical waves. Sound waves therefore need a medium to propagate, while electromagnetic waves do not need a medium. This is the main difference between sound waves and electromagnetic waves. There are many other differences between the two. This article tries to explain them in detail.
What is a sound wave?
Sound waves are mechanical waves that are generated by mechanical vibrations. For example, when your phone rings, it vibrates around it, creating compression and dilution in the air. This compression and dilution spreads through the air. When they reach our eardrum, they make the eardrum vibrate; we perceive that as sound. You need a material medium to propagate, since it is mechanical waves. Therefore, sound waves cannot travel through a vacuum.
Sound waves propagate as longitudinal waves through air, liquids and plasma. In solids, on the other hand, sound waves can propagate both as longitudinal waves and as transverse waves. However, the speed of sound depends on the material properties. In air, the speed of light increases with temperature.
For the sake of simplicity, sound waves are classified into three bands as follows.
Infrasound - frequencies below 20 Hz
Audible tone - frequencies between 20Hz and 20000Hz
Ultrasonic frequencies over 20000Hz
Longitudinal sound waves cannot be polarized because only transverse waves can be polarized.
In addition, sound waves are mainly characterized by their pitch, volume and quality.
What is an electromagnetic wave?
Electromagnetic waves are generated by accelerating or decelerating charged particles. They are transverse waves. As a result, electromagnetic waves can be polarized. In contrast to all other types of waves, electromagnetic waves contain a magnetic field and also an electric field that oscillates perpendicular to each other and perpendicular to the direction of propagation of the wave. These waves carry energy in the direction of propagation of the wave. They can propagate through a vacuum since they are not mechanical waves. They can spread through air, liquids, or solids. However, electromagnetic waves are attenuated as they move through a material medium. The degree of damping depends on the material properties of the medium through which the electromagnetic waves propagate. Electromagnetic waves propagate in a vacuum with 3 × 10 8 ms -1 . In every material medium the speed of the waves and their wavelengths decrease.
The frequencies of electromagnetic waves have an extremely wide range. The properties of waves depend on the frequency , amplitude , etc. Therefore, for practical reasons, electromagnetic waves are classified into several bands, namely radio waves , microwaves, infrared, light, UV, X-rays and rays . Overall, the entire range is referred to as the electromagnetic spectrum.
Difference between sound waves and electromagnetic waves
Sound waves: Sound waves are generated by mechanical vibrations.
EM waves: EM waves are generated by accelerating (or decelerating) charged particles .
Sound waves: Sound waves are generated by musical instruments, speakers, tuning forks, etc.
EM waves: EM waves are generated in current-carrying wires, black body radiation.
Speed in vacuum
Sound waves: Sound cannot travel through a vacuum.
EM waves: EM waves propagate with the speed of ms -1.
Speed in the air
Sound waves: The speed of sound in air increases with temperature.
EM waves: The speed of EM waves in air is slightly slower than in a vacuum.
Sound waves : longitudinal sound waves cannot be polarized.
EM waves: EM waves are polarizable.
Sound waves: Sound waves cannot excite atoms.
EM waves: EM waves can excite atoms.
Sound waves: Sound waves create hearing.
EM waves: EM waves produce vision.
Sound waves: There are many uses including musical instruments, ultrasound scanning, ultrasonic cleaning, sonar equipment, mineral exploration, petroleum exploration, consumer electronics, and hearing.
EM waves: There are hundreds of uses. In general, these applications are listed under the relevant bands of the electromagnetic spectrum as most applications depend on the frequency of the EM waves.
Radio wave radio broadcast, etc.
Microwaves - microwave ovens, televisions, cell phones, etc.
Infrared remote controls.
Visible light - vision, photosynthesis,
Ultraviolet-UV Visible Spectroscopy
X-ray diagnostics in medicine, X-ray crystallography.
γ-radiation radiation therapy to sterilize medical equipment.