Visible light and ultraviolet light are similar and not so similar. They are each a portion of the electromagnetic spectrum. Humans can detect, through our eyes, the visible light spectrum. As humans, we aren’t able to see ultraviolet light.
When we compare the two, we primarily concern ourselves with the effects of visible light and ultraviolet light in relationship to sunglasses and sunburns.
When we move beyond the sunglass and sunburn equation, what’s the real difference between visible light and ultraviolet light? Is one of them better than the other? Let’s jump in and take a look at the topic.
Visible Light vs. Ultraviolet Light: Side-by-Side Comparison
|Visible Light wavelength||Ultraviolet Light Wavelength||Common Use|
|Wavelength||380 – 700nm||100 – 400 nm||Photography, Fiber Optic communication, Illumination|
|UV-A||Not Applicable||320 – 400 nm||Cancer treatment|
|UV-B||N/A||290 – 320 nm||Tanning Beds|
|UA-C||N/A||100 – 290 nm||Med. Equip. Sterilization|
Visible Light vs. Ultraviolet Light: What’s the Difference?
To understand the difference between visible light vs. ultraviolet light, we need to shine a light (get it?) on the electromagnetic spectrum as a whole. The EM spectrum is something that impacts our daily lives.
Perhaps you didn’t know it, but the device you’re reading this article on has properties directly correlated to the electromagnetic spectrum! Let’s dig in!
Electromagnetic Spectrum: What Is it?
The electromagnetic spectrum is how we identify different wavelengths of electromagnetic radiation. It has seven different wavelength bins or categories: gamma rays, X-rays, ultraviolet, visible, near-infrared, infrared, and radio.
In the image above, gamma rays (far right side of the image) have the shortest wavelengths and the highest frequency (Hz). Radio waves have the slowest frequency (Hz) and the least amount of energy (far left of the image).
Visible light and ultraviolet light are two different ranges of wavelengths.
The portion of the electromagnetic spectrum we can see with our eyes is called “visible light.”It has a wavelength between 380 and 700 nanometers. Different colors have different wavelengths.
|Violet||380 – 440|
|Blue||440 – 485|
|Cyan||485 – 510|
|Green||510 – 565|
|Yellow||565 – 590|
|Orange||590 – 625|
|Red||625 – 740|
An easily recognized source of electromagnetic radiation is the Sun itself! While the Sun radiates energy among the wavelengths of the electromagnetic spectrum, we notice it primarily in the visible light spectrum.
We are surrounded by visible light! The image above demonstrates the different colors of light in the visible light spectrum and their corresponding wavelengths.
Visible Spectrum via a Prism
In the 1660s, Sir Issac Newton discovered that “white light” from the Sun is a combination of all the colors listed in the image above. If we take a prism and focus light through it, here’s what we’ll see:
- When visible light passes through a clear triangular prism, the light separates into different colors; when visible light travels from the air into the clear triangular prism, the speed changes.
- The air and the prism have different refractive indexes. (The speed of the light traveling through the air and the speed of the light traveling into the prism).
- The change in the refractive index between the air and the prism causes the light to “bend” when it enters it The light will bend again when it exits the prism. Longer wavelengths (like red) refract less. Shorter wavelengths (like violet) refract more.
The human eye cannot detect ultraviolet light, but (fun fact!) birds, fish, some reptiles, and your favorite dog and cat can see it!
Johann Wilhelm Ritter discovered ultraviolet light in 1801. Ritter exposed silver chloride photographic paper to sunlight that he split with a triangular glass prism. He then measured how much each section of the paper darkened from the exposure to the light.
The area with the most significant level of darkening was located adjacent to the visible violet light section on the photographic paper. “Ultraviolet was born.”
Ultraviolet light falls into three different categories: UV-A, UV-B, and UV-C. In the image above, the ultraviolet light portion of the electromagnetic spectrum falls between 100 – 400 nm.
|UV-A||315 – 400 nm||Medical treatments|
|UV-B||280 – 315 nm||Tanning Beds|
|UV-C||100 – 280 nm||Medical Device Cleaning|
The longest wavelength of the ultraviolet spectrum, UV-A, has the longest UV wavelength. UV-A causes skin issues related to UV exposure, like sunspots and wrinkles.
The longer wavelength allows UV-A to pass through our outer layer of skin (epidermis) and reach the next level of the skin (dermis). UV-A penetrates clouds and automobile windshields. And UV-A will give your dermis a sunburn on a cloudy day.
UV-A is commonly used for nail gel drying and emulsion paint curing.
Not to be outshined by UV-A, UV-B also causes sunburns. While UV-A has a longer wavelength, UV-B has a shorter wavelength of approximately 280 – 315 nm.
The wavelength is too short to penetrate the epidermis. Sunburns from UV-B will be contained to the very top level of the skin. UV-B rays are tied to skin cancer. Their intensity varies depending on the season and time of day.
Exposure to UV-B allows the body to produce vitamin D, which aids in muscle and bone health. In the Pacific Northwest, it’s pretty common to consume mega doses of vitamin D in the wintertime when the skies are dark and the Sun is hidden from November through June.
The shorter the wavelength, the greater the frequency. UV-C has the shortest UV wavelength and the highest level of harmful UV radiation. The good news for us mere earthly human mortals is that the ozone layer absorbs UV-C and doesn’t penetrate the atmosphere.
UV-C is commonly used in artificial devices such as lasers, mercury lamps, (older) tanning beds, welding torches, and germicidal UV applications. As with any industrial use scenario, extreme care should be taken when you are in close proximity to a UV-C device.
When the ultraviolet wavelength is less than 290 nm, UV-C light can kill microbes on surfaces, in the air, and in the water — the properties of UV-C light can damage pathogen cells by altering and modifying their DNA.
UV-C may be used in a UVGI (ultraviolet germicidal irradiation) application to disinfect the air we breathe in public spaces. A fixture is installed in the air ducts or ceiling to eradicate airborne pathogens (like COVID-19). The fixtures are modified to prevent UV human exposure.
Visible Light vs. Ultraviolet Light: 10 Must-Know Facts
- Visible Light and ultraviolet light are two sections of the electromagnetic spectrum.
- Ultraviolet light was discovered in 1801 by Johann Ritter.
- In the 1660s, Sir Issac Newton discovered that sunlight (white light) combines seven different colors. The colors are based on wavelengths. A triangular glass prism may separate these wavelengths.
- Visible light is observable by humans, and ultraviolet light isn’t discernible by the human eye.
- Ultraviolet light has a shorter wavelength than visible light.
- UV-A has a wavelength range of 315 – 400 nm. The longer wavelength allows the ultraviolet radiation to pass through the outer layer of skin (epidermis) and penetrate deeply into the dermis (the next level of the skin).
- UV-B will give you a sunburn on the outermost layer of your skin, the epidermis. Most skin cancers are linked to UV-B exposure.
- UV-C is used to sterilize medical equipment and clean the air inside enclosed spaces (shopping malls, doctor’s offices, etc.).
- Visible light has seven different colors. Each color (violet, blue, cyan, green, yellow, orange, and red) correlates to a specific wavelength range on the electromagnetic spectrum. When sunlight passes through a clear triangular prism, visible light will separate into visible colors.
- Sunglasses don’t necessarily protect you from UV-B and UV-A. Check the label!
Visible Light vs. Ultraviolet Light: Which One Is Better? Which One Should You Use?
Visible light is a portion of our everyday life and is unavoidable (unless you’re a mole). The most common exposure to visible light is through sunlight.
Sunlight contains both visible light and ultraviolet light. Ultraviolet light is harmful to our skin and eyes, and it’s the leading cause of skin cancer. Using sunscreen and the correct sunglasses will go a long way toward ensuring vision and skin health.
Commercial products (welding equipment, lasers, etc.) require special training and equipment to protect users from harmful ultraviolet radiation.
The National Cancer Institute (NCI) states that UV radiation via the Sun, a tanning bed, or a sunlamp increases the odds of skin cancer. The International Agency for Research on Cancer (IARC) maintains that tanning lamps and beds are carcinogenic to humans.
The image featured at the top of this post is ©New Africa/Shutterstock.com.