Difference Between Mechanical and Electromagnetic Waves

Main Difference – Electromagnetic vs. Mechanical Waves

A wave is made of some type of disturbance that travels. Depending on their properties, we can classify waves into several different types. One of the distinctions is based on whether disturbances in a wave need a medium to travel through. In this way, we classify waves into electromagnetic and mechanical waves. The main difference between mechanical and electromagnetic waves is that electromagnetic waves do not require a medium to propagate whereas mechanical waves require a medium in order to propagate.

What are Mechanical Waves

Mechanical waves consist of disturbances that can only travel through a medium. You can create a simple wave by wiggling a rope up and down, and this is a mechanical wave.  When one molecule moves up, it makes the neighbouring molecules also move up, and in this way the disturbance moves all the way along the rope. Here, the rope is the medium of the wave because it is the motion of “rope molecules” that carries the disturbance along.

Another very good example of a mechanical wave is a sound wave. Sound waves are made of oscillating molecules. Typically, when we hear sound, our ear is detecting the back-and-forth motion of air molecules (you can check that sound really is made of vibrating air molecules by placing a candle in front of a speaker, see the video below). The brain interprets this back-and-forth motion of air molecules as “sound”. We can also hear sound through vibrations of other types of molecules: you can hear under water because of the vibrations in water molecules, for instance.

What makes sound waves mechanical is that the sound would not be able to propagate if there was no medium. For instance, imagine putting a ringing bell inside a vacuum jar and slowly letting the air out. As air moves out of the jar, the sound would become fainter. When there is no air inside the jar, the bell is still vibrating but there is nothing in between to carry the sound outside, so the sound stops. If you slowly let air in, you can start to hear the sound again. This experiment is shown in the video below:

What are Electromagnetic Waves

Electromagnetic waves consist of disturbances that can travel without a medium. For example, the light from the Sun is an electromagnetic wave that travels through the vacuum between the Earth and the Sun. Electromagnetic waves can do this because they do not rely on vibrating molecules. Instead, what is oscillating in an electromagnetic wave is an electric field. There is a magnetic field as well, which is oscillating in phase with the electric field, at 90o to the electric field. The vibrations are conducted in a direction that is at 90o to both the oscillations in the electric field and the magnetic field. A short animation of how these fields vibrate is shown in the video below:

In vacuums, all electromagnetic waves travel at a speed of about 3×108 m s-1. This is often called the speed of light in vacuum. Depending on their wavelength, they can be classified into several different types. The diagram blow shows these different types, starting from larger wavelengths (left) to smaller wavelengths (right).

Difference Between Mechanical and Electromagnetic Waves - Electromagnetic_Spectrum

The Electromagnetic Spectrum

Since the oscillations are at right angles to the direction of propagation, electromagnetic waves are transverse waves. This means that electromagnetic waves can be polarized.

Difference Between Mechanical and Electromagnetic Waves

Method of Propagation

Mechanical waves require a medium to propagate.

Electromagnetic waves do not require a medium to propagate. They can propagate in a vacuum.


Mechanical waves travel slower than electromagnetic waves.

Electromagnetic waves travel at 3×108 m s-1 in vacuums. When they travel through other media, they slow down a little.

Type of Waves

Mechanical waves could be transverse or longitudinal. When they are longitudinal, they cannot be polarized.

Electromagnetic waves are transverse waves, so they can be polarized.

Image Courtesy

“A diagram of the Milton spectrum, showing the type, wavelength (with examples), frequency, the black body emission temperature…” by Inductiveload, NASA (self-made, information by NASA) [], via

About the Author: Nipun

Related pages

difference between enzyme and coenzymetransnational corporations examplesliterary definition of static characterwhat is stanzas definitionhow to save java program in notepadarchaeology anthropology definitionorthopneadifference between privacy and confidentialitywhat is the difference between whiskey and brandydifference between codon and anticodonaesthetic or estheticdifference between hair smoothening and rebondingprotandry and protogynycarrier proteins and channel proteinsdifference between primary succession and secondary successionparchment paper vs wax paperconcrete noun and abstract nounadjectives for numbersplains and plateausfructose and glucose differencedifferences between animal and plant mitosisflora and fauna wikipediaexamples of spoonerismwhat is the difference between tone and mood in poetryexplain the difference between transverse and longitudinal wavesdifference between latte and flat whiteexamples of amorphous solidsdefine valance electrondifferentiate between gymnosperms and angiospermsdada surrealismbi-annually definitionenquiries vs inquirythermoplastic settingdouble entenderconservation of linear momentum problemswhat is the difference between monozygotic and dizygotic twinsadp molecule diagrammeaning of the word alumnidelusions or hallucinationsfossil artifactsdextrin molecular weightdrafting tools and equipments and their useswhat is elastic and inelastic collisiondefine kinematic viscositybicarbonate soda same as baking sodarupture strength definitiondifference between plumule and radiclecentroidal rotationlight microscope and electron microscope similaritiesnoun of provelist of grams and pulsescad cvdsmooching and kissingintrons vs exonsarr ratedefinition for multicellularendnote vs footnoteligroin chemical structuredifference between circular and rotational motionsimilarities thesaurusnaming enzymesvaporization chemistry definitionphase velocity vs group velocity2d echo test procedurethe difference between grammar and syntaxdifference between pastry and bakerysulphate ion testexamples of temporary magnetsoxymoron definition in literaturedifferentiate gram positive and gram negative bacteriadifference tortoise turtledentition of carnivoressardonic expressiondifference between algae and fungiavalanche diode symboldefinition motif in literatureexamples of moneransde jure vs de factohereditary disease exampleswhat is the difference between gerund and participle