How Fast Do Radio Waves Travel In A Vacuum-Air-Space is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no extra cost to you. Learn more.

The effective use of radio waves in communication technologies today is based on how fast radio waves travel.

Radio waves play a significant role in most of the technology solutions we see around us.

But, as common as they are, very little is known about them. For most people, they don’t even know the meaning of radio waves.

There is a lot of misconception out there regarding radio waves. From what they are to how they function, only a handful of people know anything about this wave type.

As a result, this post will be breaking down everything you need to know about radio waves.

By the time you are done reading this, you should be confident enough to tell someone else exactly what radio waves are and how they function.

What are radio waves?

Unlike what many people think, radio waves are not the sounds you hear coming out of your radio speakers. That is sound waves, not radio waves.

Radio waves are electromagnetic radiation. Radio waves are quite similar to light waves. The only difference is that you cannot see them as light.

Think of them as being produced by charged particles going through acceleration, like in time-changing electric currents.

Transmitters artificially generate them. You need a radio receiver to intercept and receive the radio waves with the help of an antenna.

The application of radio waves is used in many technologies.

They are employed in mobile and fixed radio communication, radar & navigation systems, broadcasting, wireless computer network, communication satellites, and a host of others.

Radio waves were discovered by James Clerk Maxwell, the physicist who was known for the famous Maxwell’s Equation around the 1870s.

A German physicist known as Heinrich Hertz was the one who advanced Maxwell’s prediction of radio waves.

He was the first to apply Maxwell’s equation to the transmission and reception of radio waves.

The unit of frequency for EM waves was unanimously agreed to be Hertz by the American Association For The Advancement of Science, in honor of Heinrich Hertz.

Properties of radio waves

Radio waves have got some highly distinct properties that you ought to be aware of. Those properties will be outlined below

  • They are a form of electromagnetic waves. They have got a wavelength longer than the wavelength of infrared light.
  • Radio waves can go through materials or obstacles.
  • They can travel extremely long distances.
  • Radio waves are invisible and cannot be felt either.
  • When they move through a vacuum, they do so at the speed of light. But, their speed drops when they move through a medium, depending on the medium’s permeability.
  • Radio waves have a wavelength range between thousands of meters and 30cm.
  • Radio waves can be formed as a result of changing electric currents. Naturally, they can be emitted by lightning and astronomical objects that can exhibit magnetic field changes.
  • Radio waves possess both magnetic and electric components
  • They can experience absorption, refraction, reflection, as well as polarization.

Types of Radio Wave

Radio waves are subdivided into various categories. This section of this post will be discussing the different radio waves, as seen below.

Low to medium frequencies

This frequency range is the first category in the radio frequency spectrum. It is composed of extremely low to medium radio waves.

ELF and VLF stand for extremely low frequency and very low frequency, respectively. This class of radio waves operates with a frequency of between 0.1 and 30 kHz.

They are classified as the lowest radio frequencies. They’ve got long-range capabilities that make them suitable for communication items in submarines.

That is because they can penetrate water and rocks. They have also found useful applications in caves and mines.

Higher frequencies

HF, VHF, and UHF bands comprise public service radio, broadcast television sound, cellphones, FM, and GPS.

These bands employ FM or frequency modulation to impress or encode a data or audio signal upon the carrier wave.

In FM, the signal’s amplitude is kept constant, while the frequency is varied along with the magnitude and rate that corresponds to the data or audio signal.

That is why the signal quality of FM is better than that of AM. Environmental factors do not have a similar influence on frequency as they do on amplitude.

Furthermore, the FM receivers are built to ignore any amplitude variations so long as the signal maintains the least threshold value.

Shortwave radio

Shortwave radio makes use of frequencies between 1.7 kHz and 30 MHz.

This frequency range is what is used to transmit radio signals from shortwave stations across the globe.

Stations like the BBC, VOA, Voice of Russia, and hundreds of other stations use this frequency range for broadcast purposes.

Shortwaves are preferred for long-distance broadcast due to their signals’ ability to reflect on the ionosphere and rebound back far away from where the signal has been broadcast.

Highest frequencies

Super high frequency (SHF) and extremely high frequency (EHF) are considered among the microwave band of the radio-frequency spectrum.

With the help of this frequency range, high-bandwidth, short-range communications can happen between fixed locations.

SHF is used in applications such as Wi-Fi, wireless USB, and Bluetooth. They are also employed for radar purposes because they possess the ability to bounce off obstacles.

It is noteworthy that SHF can only function in straight paths. They bounce off any obstacle they come in contact with.

How Fast Do Radio Waves Travel? Through Space, Air or Vacuum

How fast do radio waves travel has been answered so many times, yet some people are still confused about the subject.

Earlier, we were able to establish that radio waves are electromagnetic. That means they are going to behave like electromagnetic waves too.

One thing that is common to all electromagnetic waves is that they all travel at the speed of light in a vacuum. They travel at an approximate speed of 186,000 miles per second in a vacuum.

Unlike radio waves, sound waves cannot travel through a vacuum. They can only travel through a medium.

In other words, without a medium, you cannot have sound. Radio waves do not necessarily need any medium for their propagation.

Radio waves travel at the same speed as light because they are like light waves, except that they are unseen.

Radio waves can equally travel through various mediums at different speeds. How fast they are going to travel through a specific medium will be determined by some factors.

Some of those factors include the permittivity and permeability of the medium in question.

Radio waves are much faster than sound waves, even if you have to pass them through the same medium for the sake of comparison.

How do radio waves work?

The best way to answer how do radio waves work is by using antennas to explain the concept.

For radio waves to be effectively broadcast and received, we will need two antennas. One will be the transmitter, while the other will be the receiver.

Let’s use a radio station as an example. At the radio station, voice can be captured by a mic, where the system will convert it into a form of electrical energy.

That electricity is then sent through an antenna (transmitter) with great height. The transmitter will boost the power of the electricity so it can travel as far as possible.

The tiny particles within the electric current continuously move back and forth within the antenna, and radio waves are automatically produced.

The radio waves then travel at the speed of light or close to that value, with the voices trapped within them.

Therefore, when someone puts on their radio set, the electrons in their antenna are made to move back and forth (vibrated) by the incoming radio waves.

That resonating action brings about an electric current. The electronics component then converts that electric signal to sound, allowing you to hear the voice recorded at the station.

Why do radio waves travel at the speed of light and not sound?

Sound waves need a medium before they can travel between locations.

For example, let’s take the air; sound waves can travel through the air because it is composed of molecules.

Without any molecules in the air, it will be impossible to transmit sound waves across the atmosphere. That is where radio waves differ from sound waves.

Radio waves travel at the speed of light because both light and radio waves belong to electromagnetic waves.

Sound waves do not belong to this class. Instead, they are grouped in the class of mechanical waves.

All electromagnetic waves can travel through a vacuum at the speed of light. So that is the simple reason radio waves tend to travel at the speed of light and not sound waves.

FAQs Regarding The Speed of Radio Waves

Do all the different types of radio waves travel at the same speed?

The radio frequency spectrum is a composition of the different types of radio waves.

But because the radio waves are a part of an electromagnetic spectrum, they will all travel at the same speed across a vacuum.

That speed is the speed of light. Having said that, if they are to travel across different mediums, then their speeds will vary.

Do radio waves continue in outer space?

Yes, radio waves continue indefinitely until they come in contact with something.

But, even before that happens, they usually become weak and blend with the universe’s background noise.

That means the first set of radio waves emitted into outer space must be over a hundred light-years old by now.

What is the speed of red light in a vacuum?

Light travels through a vacuum at a constant speed. The speed at which light travels through a vacuum has nothing to do with its polarization, frequency, or other light wave characteristics.

In other words, the color of the wave does not affect its speed in a vacuum. Whether it is blue or red light, it will travel at an approximate speed of 300,000 km per second.

Does Wi-Fi make use of radio waves?

Just like other wireless devices, Wi-Fi implements radio frequencies for sending signals between devices.

The range of radio frequencies employed by Wi-Fi is quite different from devices like cell phones, car radios, weather radios, or walky-talkies.

For instance, your car radio receives frequencies in the range of between Kilohertz and Megahertz, suitable for AM and FM stations, respectively.

Wi-Fi, on the other hand, implements its data transmission in the region of Gigahertz. So, in general, you can say that Wi-Fi uses radio waves for transmitting data between devices.

What are some of the uses of radio waves?

Radio waves possess the longest wavelengths in the EM spectrum. Radio waves aren’t just used for transmitting radio signals that your radio can pick up.

They are actively responsible for carrying the signals you use for your cell phones and TV.

The moment your TV antenna picks up an incoming signal from a TV station, it does that in the form of radio waves or EM waves.

Are radio waves the only type of electromagnetic wave?

The answer to this question is No! Radio waves are not the only component of the electromagnetic spectrum.

Other forms of electromagnetic waves include Bluetooth, radar, microwaves, ultraviolet light waves, infra-red, and X-rays.

So it is right for you to assume all these components as electromagnetic waves.


Waves are generally classified into two groups – mechanical waves and electromagnetic waves.

Radio waves belong to the group of the latter. That explains the reason behind their ability to travel through a vacuum.

In stark contrast, sound waves are unable to travel through a vacuum due to their mechanical properties.

Sound waves require a medium for them to be propagated from one point to another.

Radio waves, just like other electromagnetic waves, travel through a vacuum at the speed of light.

Radio waves are employed in a wide range of technology applications. They make up the very core of communication technology.

Similar Posts:

Leave a Comment