UV Radiation and the Atmosphere
Τitle:UV radiation and the atmosphere
Basic idea:Ultraviolet light is invisible to us but can be detected using certain materials sensitive to it.
Jargon:Ultraviolet, Spectrum, Fluorescence
Ultraviolet light can’t be seen by the human eye but is a part of sunlight. It can be harmful to us if we are exposed to it (sunburn!) but it is mostly absorbed by the atmosphere. The presence of UV light in sunlight can be shown by using fluorescing UV-sensitive beads. Sunblock can absorb UV light and hence protects us against its harmful effects.
Importance in Science:
Harmful effects: Overexposure to certain kinds of UV light causes DNA damage which can lead to skin cancer.
Security: Credit cards and drivers’ licenses often include a UV watermark than can only be seen under a UV light.
Astronomy: Very hot stars emit a lot of UV light and hence can be seen by telescopes outside the Earth’s atmosphere.
Medicine: UV light is used to treat certain skin conditions psoriasis and eczema.
Credit Cards and drivers’ licenses
Extended Discussion and Demonstration
EM Spectrum and UV light:
The light that we can with our eyes is only a small part of the different wavelengths that are possible in nature. All the possible wavelengths together are called the “Electromagnetic (EM) Spectrum.” The term electromagnetic is used because light is an electromagnetic wave, consisting of oscillating electric and magnetic fields. The visible part of the EM spectrum ranges in wavelength from 400 to 700 nm. The color red has a wavelength of 700 nm while blue has a wavelength of 400 nm. Any wavelength longer than 700 nm is called infrared (IR) and any wavelength shorter than 400 nm is called ultraviolet (UV).