how does ultraviolet light work?
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Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. It can be subdivided into near UV (380–200 nm wavelength), far or vacuum UV (200–10 nm; abbrev. FUV or VUV), and extreme UV (1–31 nm; abbrev. EUV or XUV).\n\nWhen considering the effect of UV radiation on human health and the environment, the range of UV wavelengths is often subdivided into UVA (380–315 nm), also called Long Wave or "blacklight"; UVB (315–280 nm), also called Medium Wave; and UVC (< 280 nm), also called Short Wave or "germicidal". See 1 E-7 m for a list of objects of comparable sizes.\n\nIn photolithography, in laser technology, etc., the term deep ultraviolet or DUV refers to wavelengths below 300nm.\n\nThe name means "beyond violet" (from Latin ultra, "beyond"), violet being the color of the shortest wavelengths of visible light. Some of the UV wavelengths are colloquially called black light, as it is invisible to the human eye. Some animals, including birds, reptiles, and insects such as bees, can see into the near ultraviolet. Many fruits, flowers, and seeds stand out more strongly from the background in ultraviolet wavelengths as compared to human color vision. Many birds have patterns in their plumage that are invisible at usual wavelengths but seen in ultraviolet, and the urine of some animals is much easier to spot with ultraviolet.\n\nThe Sun emits ultraviolet radiation in the UVA, UVB, and UVC bands, but because of absorption in the atmosphere's ozone layer, 99% of the ultraviolet radiation that reaches the Earth's surface is UVA. (Some of the UVC light is responsible for the generation of the ozone.)\n\nFor additional information, click link below:
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UVA:\nCan pass through window glass.\nIs not affected by a change in altitude or weather.\nIs present all day and every day of the year.\nPenetrates deep into skin layers.\nIs 5% of the sun's rays.\nIs 20 times more abundant than UVB rays.\nAffects long-term skin damage.\n\nUVB:\nCannot pass through window glass.\nCauses sunburn.\nCauses tanning.\nHelps the body with normal vitamin D production.\nVaries with the season. It is more intense in the summer than in the winter.\nVaries with weather conditions.\nIs more intense at midday than in the morning or late afternoon.\nIs more intense at high altitudes and near the equator.\nIs 0.5% of the sun's rays.\nIs protected against by the sun protection factor (SPF) in sunscreens.\nIs related to more than 90% of nonmelanoma skin cancer.\nIs related to cataracts.\n\nMore:\n\nHow Sunlight Works\n\nSunlight arrives on earth in three forms: infrared (heat), visible light and ultraviolet. Ultraviolet light is classified into three categories: \nUVA (315 to 400 nm), also known as black light, which causes tanning \nUVB (280 to 315 nm), which causes damage in the form of sunburn \nUVC (100 to 280 nm), which is filtered out by the atmosphere and never reaches us. \n99% of the sun's UV radiation at sea level is UVA. It is the UVB that causes most of the problems related to sun exposure: things like aging, wrinkles, cancer and so on, although research is increasingly implicating UVA as well. \nOne of the interesting things about UV radiation is that it is reflected by different surfaces. These reflections can amplify the effects of UV exposure. For example, snow reflects 90% of UV light. That is why you can get snow blindness and severe sunburns from skiing on a sunny day. Sand can reflect up to 20% of UVB that hits it, meaning that you can get extra UV exposure at the beach. \n\nOn the other hand, certain things absorb almost all UV radiation partially or completely. Glass is one of these substances - many glasses are very good absorbers of UV (which is why you may have heard that you cannot get sunburn in a greenhouse - just make sure it is glass and not plastic covering the greenhouse!). Most sunscreens use chemicals that have the same UV-absorbing properties.
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If it is truly only emitting ultraviolet light then it would not produce any visible spectrum light.
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Sanity check. Ultraviolet light is energetic light, which will break bonds, which is why it can be dangerous. UV light is shorter than about 400 nm. So after throwing around the big exponents, we want an answer less than 400 nm, but probably larger than 100 because then it's x-rays, which is usually overkill for breaking molecules apart. \n941 kJ / mol means 941,000 joules are sufficient to break \n6.02x10^23 molecular bonds. ( 1 mol is Avagadro's number)\ndivide it out and get how much to break just one N2 bond:\n941,000 J / 6.02x10^23 molecules = 1.56 x 10^-18 joules\nWhat wavelength of light corresponds to that amount of energy being packed into one photon? \nE = hc / lambda, where h = 6.63x10^-34 m2 kg/s (Planck), c = 2.228x10^8 m/s (speed of light), and lambda is wavelength in meters (staying in mks units, E will be in joules). Solve for lambda, where E is 1.56 x 10^-18. \nlambda = hc/E = 1.274 x 10^-7 meters\nmultiply by 10^9 to get nm, then lambda = 127.4 nm\nLooks good to me...  There might be a simpler cookbook equation to get this answer, but it's good to know how to do it from the basic constants of nature. \n\nNote: previous answer left out factor of Avagadro's number and did no sanity check...
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when light is thrown upon the atoms..it provides energy..which is taken up by the electrons and they escpae from the surface of the metal..called as photons.
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infrared and ultraviolet!
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UV light will destroy it
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UV rays are just a "color" of light that cannot be seen by humans. It has too short of a wavelength. UV is typically broken down into UVA and UVB. \nAmongst other things, UV light can be used for gettnig a nice tan, curing some adhesives, damaging most kinds of plastics (take a look at the dashboard of an old car - that cracking is due to UV damage)
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It works on photo electricprinciple.\n\nBasic is a light source and a reflective surface(mirror).\n\nCircuit either stay normaly open or shute but when the beam is broken it provides a signal which in turn operates a system, say bell or a motor, that can open a door.
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turns light into energy.\n\ncharge a battery for free
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Fluorescent lights don't emit enough UV light to be dangerous to your eye.  You do want to make sure that you're always wearing sunglasses outside, though.
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It is true. \nLight is a radiation- simply said  it is an energy that flying away from something.What we call light is just a certain range that electromagnetic radiation that we can perceive with our eyes. in reality the frequency of that radiation is much greater that we can see with our eyes. on the low end of it- there the length of the waves are longer are the heat waves. On the high end where we stop seeing violet light - radiation doesn't stop, just waves get shorter and shorter and we call it ultra violet light. Just because we don't see it, it doesn't mean that nature doesn't use it. Flowers have their elaborate patterns in Ultra Violet colors that bees see, that lead them to nectar.
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UV Light is really good for skin conditions like psoriasis, you can ask you doctor to reefer you for it, or you can buy a small portable face tanner - my dad used one for his psoriasis and it worked really well, but talk to you doc first to see how long/often you should use it
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"Color Changing UV Beads"\nhttp://www.stevespanglerscience.com/product/1350\n\n"The UV-sensitive beads contain a pigment that changes color when exposed to ultraviolet radiation from the sun. The energy beads are not affected by light from light bulbs that do not emit ultraviolet light. The beads will remain white indoors, when shielded from sunlight."
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UV invisible ink is made using a volatile application base, and mixed into it is a compound that is transparent to visable wavelengths of light but not UV. When you shine UV light on it, the compound fluoresces and the wavelength of the light is increased during thing process therefore allowing you so see the bright blueish/purpleish mark of the ink.
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Ultraviolet light is able penetrate through the outer cells of our integument (skin). Doing this exposes the DNA to potential damage. \n\nThe damage that is proposed to be caused by the UV light has changed in recent years. It used to be thought that UV light caused the base pairs to fuse (a base pair refers to the fact that complimentary bases from opposite strands hydrogen bond with one another -- Adenine (A) bonds with Thymine (T); Guanine (G) pairs with Cytosines (C). Howver, it's been recently shown that as sunlight warms our skin, UV photons are absorbed by the bases, causing their electrons to vibrate. These high-energy vibrations nudge the atoms in the bases around. If all goes well, the DNA returns to normal after the energy wave passes. But some of the time, the atoms don't return to their original positions, and new chemical bonds are formed.\n\nScientists know that such accidental bonds create "photolesions" - injuries that prevent DNA from replicating properly. The details of the process aren't fully understood, but studies suggest that photolesions cause genetic mutations that lead to diseases such as sun damage as well as cancer.\n\nBecause skin cells need to replicate often this damage can either slow them down causing skin damage or speed them up to the point of becoming cancerous.
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UV radiation from the sun has always played important roles in our environment, and affects nearly all living organisms. Biological actions of many kinds have evolved to deal with it. Yet UV radiation at different wavelengths differs in its effects, and we have to live with the harmful effects as well as the helpful ones. Radiation at the longer UV wavelengths of 320-400 nm, designated as UV-A, plays a helpful and essential role in formation of Vitamin D by the skin, and plays a harmful role in that it causes sunburn on human skin and cataracts in our eyes. Radiation at shorter wavelengths of 290-320 nm, designated as UV-B, causes damage at the molecular level to the fundamental building block of life— deoxyribonucleic acid (DNA).