rays anyway? UV stands for Ultraviolet light, which is an invisible light wave to humans, but can be seen by some insects such as the bumblebee. Ultraviolet light is part of the Electromagnetic Spectrum. You have already come into contact with this light wave.UV rays are emitted from the sun and stars as part of cosmic radiation. Scientists like to study UV rays because it helpts to learn more about Cosmos. Some of the Ultraviolet rays are absorbed by the Earth's atmosphere, however many of them still make it through. UV rays travel at the speed of light, as do any other parts of the EM Spectrum. The frequencies[1] of UV rays range from 7.5×10^14 to 3×10^17 Hz, while the wavelength ranges from 4×10^−5 to 10^−7 cm. There are three regions of ultraviolet light: near (closest to visible light), far (most unknown), and extreme (closest to X-ray). The three regions have "different energies of ultraviolet radiation"[2]. The energy ranges from 3 to 10^3 eV, which makes it more energetic than visible light, and allows it to create more harm.
The effect of UV rays can be seen when every year people come back
from vacations with a full-blown sunburn. The energy of the UV light allows it to break up molecules when absorbed by the skin. Also, it can penetrate deeper than visible light, which makes the damage more serious. If the UV rays damage the DNA of a skin cell, then it has the potential to cause melanoma[3], a very dangerous form of skin cancer, so people must wear sunscreen.The same ability to break up molecules allows UV rays to not only harm, but to help with sanitation purposes. Water Coolers and Dispensers you can find in offices contain a UV sanitation filter system. This idea gives the basis for SODIS, a Swiss-water disinfection program used in many third world countries to provide water safe to drink[4]. In Tanzania, Ndolela Primary School has been using SODIS since 2006. They experienced fewer cases of diarrhea, which increased attendance at the school. In return, the percentage of students passing the 6th Grade Exam increased from 15% to 95%. This is how UV rays helped with proficiencies at this school.
Photo Credit: NASA
National Cancer Institute
References:
1. Eberhard Sengpiel, Sengpielaudio Search Engine, Calculator - Wavelengths, 2. Radio waves and Light waves in a vacuum
2. Ruth Netting, NASA, The Electromagnetic Spectrum
3. National Cancer Institute, Melanoma
4. Mark Jenkins, National Geographic Water April 2010 Issue, Energy
6 comments:
Wow your blog was really cool Roberta! I didn't really understand how your first picture related to the subject though but you had a lot of good information.
The applications for UV Rays are really interesting!! It is surprising that it can clean water so well! Do you know how our water is cleaned?
I like that you connected UV rays to drinking water to increased school grades. Very interesting.
Great job Roberta. Now I know why sunscreen is so important because of what it exactly does to the skin. I found that amazing that one school in Tanzania had such amazing results because of that water UV system. It seems this kind of wave has many different uses. Good job.
I also did Ultraviolet Light! I found that it was very clever of you to begin the blog with stating UV rays increase intelligence howver, not reveal how until the end. In answer to Sam's question, the first picture relates because it is an example of an insect that can see ultraviolet light, the bumblebee.
Thanks guys. You're absolutely right Nikki!
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