What is The Speed of a Radio Wave in a Vacuum?

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What is the speed of a radio wave in a vacuum? Radio waves are a variety of electromagnetic radiation. They are highly used in electromagnetic technology. Things like television, smartphone, radio devices, are constantly using radio devices for primary communication. Later these devices convert the waves into mechanical waves for ease of communication.

If you are wondering about the speed of a Radio wave in the vacuum, then you have arrived in the right place. In the below part of the article, we will let you know how the radio wave travels in the vacuum and what is the speed of the radio wave when traveling through the vacuum.

Electromagnetic Wave and Vacuum Wave

The radio wave is a variation of electromagnetic radiation. Now you might want to know what are mechanical waves and electromagnetic waves. Well, they are two different variations of ways by which energy is transported around the world. Mechanical waves typically travel as vibration. Two of the examples of mechanical waves can be the sound wave and the waves you see in the water.

Mechanical waves require vibration to be created. As a result, there must be a matter that can move the waves from one point to another. Some of the examples of the matter can the air or gas, and other things in solid, liquid, and the plasma forms. The waves in the water we see are created through the vibration in the liquid. Following the same way, the sound we hear travel through the air by vibrating the next air particles.

The sound waves as well as the other mechanical waves cannot travel through a vacuum. That is because there are no matters in the vacuum that can cause the disturbance or vibration to move the particles. On the other hand, the electromagnetic waves are a change of the magnetic field. What makes the electromagnetic wave different is it doesn’t require a medium for traveling. As a result, the electromagnetic wave can travel through anything.

It can travel through the air, solid materials, and even the vacuum space. Although there are no matters in the vacuum, the electromagnetic wave can still travel through it. That is because the electromagnetic wave doesn’t require any sort of medium to travel. They can travel from one point to another without any medium or matter.

The Speed of a Radio Wave in a Vacuum

The radio waves are just a small part of the electromagnetic wave. As we discussed earlier, they are vastly used in the communication technologies. You will often find the use of the radio wave in different communication technologies including radio, television, mobile, and smartphones. The radio-frequency spectrum is a little portion of the EM spectrum.

The EM or electromagnetic spectrum is divided into seven parts, which helps to decrease the wavelength while in the meantime also increase frequency. Some other companion of a radio wave in the EM spectrum includes the ultraviolet, visible light, IR, X-rays, etc.

Now the question is what is the speed of the radio wave in a vacuum? Well, the radio wave being an electromagnetic wave, can easily travel in a vacuum. Just like any other electromagnetic wave, the radio wave also doesn’t require any sort of medium or matter for traveling in the vacuum. The speed of the radio wave is equal to the velocity of the light in the vacuum which is 299,775 km/s. Interestingly, the speed is the same for all other waves. What it means is different variations of the electromagnetic wave works at the same speed in the same medium.

One thing about the radio wave along with the other electromagnetic wave is it changes with some factor. Such as when the wave propagates at a height of a fraction of a wavelength, their speed slightly reduces. The amount of reduction will depend on the electrical conductivity of the earth. When it comes to overland transmission, the speed will be mostly the same as the regular speed.

When does the Speed Increase?

Do you know that the speed of the radio wave can increase sometimes? It when especially in the case of refractive index decreases upon the height transmission. As a result, the speed of radio waves upsurges towards the velocity of the light. As an example, centimeter waves that were propagated at a certain height seemed to travel at a speed of 299,690 km/s. Moreover, when the waves are transmitted between a flying aircraft and the ground, the speed will increase a few kilometers more.

Why Mechanical Wave Cannot Travel in Vacuum?

To understand this, you first need to understand how the mechanical wave works. The electromagnetic wave works through vibration. What we want to mean is vibration is the thing that transfers mechanical wave from one end to another. The vibration requires a medium to travel from one end to another. It cannot travel without a matter or medium, whatever you call it.

One of the finest examples of the mechanical wave is the sound wave. The sound we hear in the earth travels through vibration. When someone or something produces a sound, it causes vibration and the vibration vibrates the air particles. The vibrated particles near the source then vibrate the next particles around it. This way the sound propagates or spread out in an area.

To make things easier, we can take the waves in the pond as an example. When you though something in the pond, it will cause a wave around it. The wave will then vibrate the other water particles around it, creating newer waves. Following the way, the vibration spread throughout the pond. This is exactly how the mechanical waves work. As there is no particle, matter, or medium in the vacuum, the mechanical waves cannot work there.


The speed of the radio wave in the vacuum is the same as the light waves. In fact, all electromagnetic wave moves in the same speed in the vacuum. We hope this article will be helpful for understanding how different waves work in a vacuum.

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