Visible light and radio waves work in your favor in almost every moment of your life. When you turn on your favorite TV show, radio waves carry the compact signals from the station to your house, then visible light bounces the images to the eyes’ retinas, allowing you to see the beautiful scenes and colors.
Regardless of their unique functions and purposes, radio waves and visible light are both electromagnetic waves, meaning they share the same speed and travel characteristics.
How does visible light compare to radio waves? Find more details below!
| Visible light | Radio waves |
| ● Short wavelengths of 380 to 700 nanometers
● High frequencies ranging from 400 to 800 terahertz ● High energy ● Absorbed by solid objects
|
● Long wavelengths of up to hundreds of kilometers
● Low frequencies ranging from 3 kilohertz to 300 gigahertz ● Lowest energy among the seven waves in the electromagnetic spectrum ● Travel almost freely on the Earth’s surface |
| Both can travel in a vacuum at the speed of light | |
How Does Visible Light Compare to Radio Waves?
1. What are they?
The electromagnetic spectrum contains seven types of waves: microwaves, radio waves, infrared light, ultraviolet light, gamma rays, X-rays, and visible light, all of which share one similarity: they travel with the speed of light in a vacuum.
Human eyes can only detect a small portion of the electromagnetic radiation called the visible light spectrum, which allows us to see the colors and shapes of objects. The Sun, for example, is a vital source of visible light. At night, our vision would be reduced significantly.
Radio waves, on the other hand, can’t be seen. However, they can carry data from one place to another. Your FM music channel, for instance, is a product of radio waves. When a program is recorded, a transmitter converts its content into radio waves and releases the signals into the air via one frequency.
As you tune into the frequency, your radio’s antenna catches the waves and sends the signals to your radio’s receiver. Finally, the device converts the radio wave signals into sound waves that you can hear.
Fun facts: Right now, information is flowing around you in the form of radio waves without you knowing about it.
That should give you an overall picture of their functions. But in technical details, what are the differences between visible light vs radio waves?
2. Differences
01 Wavelength
Wavelength is the distance between the crests or troughs of two adjacent waves. It tells how long a type of wave spreads.
Radio waves have the longest wavelength in the electromagnetic spectrum, ranging up to hundreds of kilometers. Meanwhile, visible light has only 380 to 700-nanometer wavelengths, which is within the range that human eyes can detect.
The wavelength varies with the color of the light. Violet, for example, can be 380 to 450 nm long. On the higher end of the spectrum, red stretches from 620 to 750 nm long.
To grasp the difference between radio waves and visible light wavelength, let’s compare the shortest length of radio waves, which is around 1 mm, and the top length of visible light, which is around 700 nm. Since one million nanometers are equal to one millimeter, the shortest radio waves are 1,400 times larger than the longest visible light.
But do a radio wave and a visible light wave differ only in wavelength? No. The length of a wave affects its frequency proportionally—the shorter the wavelength, the higher the frequency the wave carries.
02 Frequency
Visible light has frequencies ranging from 400 to 800 terahertz. Similar to wavelength, the frequency of visible light changes with its color. Blue light, for instance, has a frequency of around 750 terahertz.
Meanwhile, radio waves’ frequencies run from 3 kilohertz to 300 gigahertz. Each application, such as FM radios, two-way ham radios, or cellular networks, operates on a different span of frequency.
Note: 1,000 gigahertz equals one terahertz, and 1 million kilohertz equals one gigahertz.
03 Energy
Another difference between radio waves and visible light is the energy of the photons they carry. Among the seven electromagnetic waves, radio waves photons have the lowest energy, while gamma ray ones contain the highest energy.
So, does visible light have more energy than radio wave? Yes, it does.
04 Penetration
You can still listen to the radio in a closed room, but sunlight doesn’t penetrate the walls. Why so? The answer lies in their wavelengths. Since the length of radio waves is too large, most atoms cannot stop them.
Though obstructions like buildings, trees, and hills can absorb part of a radio signal and weaken it, the majority of the wave can travel through.
05 Speed
Is the radio wave faster than visible light? No, as electromagnetic waves, they do not need a medium to travel, and they travel at the same speed—299 792 458 meter/s. That is why when using mobile phones or two-way radios, you can hear other people almost instantly.
3. Pros and Cons
Visible light is the only part of electromagnetic radiation that we can see with the naked eye. However, too much exposure to visible light can cause severe eye damage. Remember when you were told not to look directly at the sun when you were a kid? Extreme sunlight can damage your retinas beyond repair.
Radio waves have the longest wavelengths and lowest frequency in the entire electromagnetic spectrum. They help carry radio signals back and forth at an incredible speed. A downside is their low frequency, which limits the amount of data they can transmit at one time.
Conclusion
That wraps up our answer to “How does visible light compare to radio waves?” Despite both being a type of wave in the electromagnetic spectrum, visible light and radio waves share no similarity other than their speed.
Nonetheless, both have unique functions and are irreplaceable in our daily lives.