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Ultraviolet
Beginner
Causes sunburn and sterilises.
Wavelengths 10–400 nm; causes tanning, sunburn, fluorescence and sterilises surfaces. Ozone absorbs UV-C and most UV-B.
UV lamps disinfect water.
Can damage DNA.
In more detail
Ultraviolet light has wavelengths shorter than visible light, from about 10 nm to 380 nm. It can cause sunburn and fluorescence, and it drives many chemical reactions.
Real-world uses
- UV lamps sterilise surfaces and water.
- Forensic light sources reveal fluorescent materials under UV.
- Sunscreen blocks ultraviolet radiation, which damages skin and can cause sunburn.
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Frequently asked questions
Why is UV harmful?
Its photons are energetic enough to damage DNA and skin cells.
Does glass block UV?
Most ordinary glass blocks much of UV-B, but not all UV-A.
Is ultraviolet light useful?
Yes. It is used to sterilise water and surfaces, and the body uses it to make vitamin D.
Related topics in AC Circuits & EM Waves
Microwaves · Infrared · Visible light · X-rays · Gamma rays · Polarisation of EM waves