As you may know, the visible light range ROYGBIV (Red, Orange, Yellow, Green, Blue, Indigo, Violet) is only one fraction of the electromagnetic spectrum, comprising EM radiation in a frequency range of approximately 430–750 terahertz. Once you start to get lower or higher frequency than that, you enter a realm that is invisible to the human eye, with different wavelengths being produced in very distinct ways and having unique effects on matter. The EM radiation most immediately lower-frequency than visible light is called infrared, and the EM radiation most immediately higher-frequency is called ultraviolet. Starting at 11 AM EDT on 5/23 and going for 24 hours, you’ll have a chance to duke it out on Eyewire for your favorite of the two!
- Wave frequency ranges from 300 gigahertz to 430 terahertz, pushing at the very edge of visible red light, hence the name.
- In layperson’s terms, infrared radiation is usually created by objects’ heat, which is why infrared “night vision” instruments are best for trying to distinguish between warmer objects (usually living ones) and cooler objects.
- Infrared radiation is used by all kinds of professions. Meterologists use it for gauging the temperature of clouds, astronomers use it for things like detecting planets around stars, while museums and art researchers use it for examining and restoring old paintings.
- Wave frequency ranges from 750 terahertz to 30 petahertz, beginning at the very edge of visible violet light, hence the name.
- The higher frequency that ultraviolet radiation becomes, the more energetic its particles are, and thus the more it can ionize various forms of matter. Ionization is what causes damage to skin cells and creates a cancer risk. And remember, it’s not just the Sun that emits UV! Things like tanning beds produce it artificially.
- Ultraviolet radiation sometimes gets a bad rap, though! You need a certain amount of it to maintain good vitamin D and serotonin levels: about 15 to 90 minutes of daily sunlight exposure between 10 AM and 4 PM. If your skin is pale, stay on the low end, and if your skin is dark, stay on the high end. (Note that if the Sun doesn’t go above 50 degrees in the sky at your latitude and season, it won’t do much though!)
Infrared waves have a wavelength 1,000x longer than ultraviolet waves (10^-16 vs 10^-13). Does height matter? The amplitude (or height) of an electromagnetic wave is proportional to its intensity. For example, a weak X-ray and a strong X-ray would be shorter and taller, respectively. Explore the world of electromagmetic radiation in this graphic modified from xkcd.
Artwork by Daniela Gamba