Before we get startedBefore we get started

Ultraviolet LightUltraviolet Light

By: Taylor StommelBy: Taylor Stommel

DiscoveryDiscovery

• discovered by discovered by Johann Wilhelm Johann Wilhelm Ritter, a German Ritter, a German physicist physicist

• also credited with also credited with the invention of dry the invention of dry cell and dry cell and dry storage batteries, storage batteries, in 1801 in 1801

What is it?What is it?

• a type of electromagnetic radiationa type of electromagnetic radiation

• has a wavelength shorter than that has a wavelength shorter than that of visible light but longer than that of of visible light but longer than that of and x-ray; approximately 300 to 400 and x-ray; approximately 300 to 400 nanometers of radiation nanometers of radiation

• degrades the components of paper, degrades the components of paper, photographs, inks, paints, and photographs, inks, paints, and adhesives adhesives

How does it work?How does it work?

• every radiation substance produces every radiation substance produces ionization energy ionization energy

• ionization energy below the ultraviolet ionization energy below the ultraviolet spectrum is largely absorbed by matter spectrum is largely absorbed by matter

• as you go higher up the spectrum, the as you go higher up the spectrum, the ionization levels of many of the molecules ionization levels of many of the molecules in matter exposed to UV light is reached in matter exposed to UV light is reached

• . when the ionization level is reached, . when the ionization level is reached, photoionization takes place photoionization takes place

How does it work? How does it work? continued…continued…• photoionization is photoionization is

dangerous because UV dangerous because UV photons above the photons above the ionization energy can ionization energy can damage and/or alter damage and/or alter atoms and molecules atoms and molecules

• a high level UV or X-ray a high level UV or X-ray will mot be absorbed will mot be absorbed

• Ultraviolet is repelled Ultraviolet is repelled by the melonin content by the melonin content in your skin (we’ll get in your skin (we’ll get to that later to that later

The SpectrumThe Spectrum

• the spectrum of light recognized as ultra the spectrum of light recognized as ultra violet light is further divided into three violet light is further divided into three subgroups, UVA, UVB, and UVC, with UVA subgroups, UVA, UVB, and UVC, with UVA rays having the shortest wave length and rays having the shortest wave length and UVC having the longest UVC having the longest

• Keep in mind that the longer the Keep in mind that the longer the wavelengths of a light on the ultraviolet wavelengths of a light on the ultraviolet section of the electromagnetic spectrum, section of the electromagnetic spectrum, the closer it is to what we know as visible the closer it is to what we know as visible lightlight

Natural SourcesNatural Sources

• the sunthe sun

• most UVB and UVC most UVB and UVC rays are absorbed rays are absorbed into the ozone layerinto the ozone layer

• 98.7% of all the 98.7% of all the ultraviolet radiation ultraviolet radiation that ever reaches that ever reaches the surface of the the surface of the earth is UVAearth is UVA

Health Related Effect on Health Related Effect on HumansHumans

BenefitsBenefits

• UVB exposure UVB exposure increased the increased the production of production of vitamin D in the vitamin D in the skinskin

• vitamin D deficiency vitamin D deficiency leads to some kinds leads to some kinds of cancer and of cancer and thousands of thousands of premature deaths premature deaths annuallyannually

ConsequencesConsequences

• too much UVB radiation too much UVB radiation results in direct damages results in direct damages to the DNA and sunburnto the DNA and sunburn

• melonin production goes melonin production goes up as the DNA is repairedup as the DNA is repaired

• melonin is a component melonin is a component that causes your skin that causes your skin tonetone

• melonin disopates melonin disopates ultraviolet light and ultraviolet light and energy as harmless heat energy as harmless heat and prevents direct and and prevents direct and indirect UV damageindirect UV damage

So…What about that So…What about that suntan?suntan?• limited sun limited sun

exposure (tolerance exposure (tolerance varies by skin tone) varies by skin tone) will reduce the will reduce the damagedamage

• sunscreen only sunscreen only protects against protects against direct DNA damage, direct DNA damage, so you might want so you might want to wear a hatto wear a hat

Applications of Ultraviolet Applications of Ultraviolet LightLight

SecuritySecurity

• in order to avoid in order to avoid having a having a counterfake counterfake mistaken as a real mistaken as a real item, many item, many creditcards, drivers creditcards, drivers lisenses, passports, lisenses, passports, etc. contain a UV etc. contain a UV water markwater mark

• ex visa card ex visa card

ForensicsForensics

• helpful in locating helpful in locating and recognizing and recognizing bodily fluids bodily fluids

• ex: blood ex: blood

AstronomyAstronomy

• very hot objects emit very hot objects emit UV radiation (ex: stars UV radiation (ex: stars and some planets)and some planets)

• can be used to identify can be used to identify kind of starkind of star

• because the ozone because the ozone layer blocks most UV layer blocks most UV rays, most rays, most observations are observations are made from spacemade from space

AuthenticationAuthentication

• can identify can identify paintings and paintings and collectables, even collectables, even dollar billsdollar bills

• different objects different objects and substances and substances flouresce flouresce differently under differently under ultraviolet lightultraviolet light

In public places…?In public places…?

• installed in public restrooms and on installed in public restrooms and on public transitpublic transit

• to deter the use of substance abuseto deter the use of substance abuse

• the blue coloring of the lights and the the blue coloring of the lights and the natural florescence of the skin make natural florescence of the skin make it harder for intravenous drug users it harder for intravenous drug users to find a varicose veinto find a varicose vein

Evolutionary SignificanceEvolutionary Significance

• because UV light causes damage to because UV light causes damage to the DNA, especially thymine bases, the DNA, especially thymine bases, as it causes them to bond together as it causes them to bond together into thyminedimers into thyminedimers

• these dimmers cannot be replicated these dimmers cannot be replicated during reproduction and result in during reproduction and result in variations in offspring in even variations in offspring in even asexual organismsasexual organisms

BibliographyBibliography

• en.wikipedia.org/wiki/Ultraviolet Ultraviolet." en.wikipedia.org/wiki/Ultraviolet Ultraviolet." wikipediawikipedia. . 020209. wikipedia. 5 Feb 2009 020209. wikipedia. 5 Feb 2009 <en.wikipedia.org/wiki/Ultraviolet>.<en.wikipedia.org/wiki/Ultraviolet>.

• Doran, Ysabel. "Who Discovered Ultraviolet Light?." Doran, Ysabel. "Who Discovered Ultraviolet Light?." ehowehow. 5 . 5 Feb 2009 <http://www.ehow.com/about_4588280_who-Feb 2009 <http://www.ehow.com/about_4588280_who-discovered-ultraviolet-light.html>.discovered-ultraviolet-light.html>.

• Dubbs, Lindsay. "Ecological impacts of UV-B radiation." Dubbs, Lindsay. "Ecological impacts of UV-B radiation." biology.duke.edubiology.duke.edu. 000405. duke education. 5 Feb 2009 . 000405. duke education. 5 Feb 2009 <http://www.biology.duke.edu/bio217/2005/lld20/index.html>.<http://www.biology.duke.edu/bio217/2005/lld20/index.html>.

• "UVA UVB skin." "UVA UVB skin." fda.govfda.gov. food and drug administration. 5 Feb . food and drug administration. 5 Feb 2009 <http://www.fda.gov/cdrh/tanning/uv_types.jpg>.2009 <http://www.fda.gov/cdrh/tanning/uv_types.jpg>.

• Nave, R. "Interaction of Radiation with matter." Nave, R. "Interaction of Radiation with matter." hyperphysics.phyhyperphysics.phy. hyperphysics. 5 Feb 2009. hyperphysics. 5 Feb 2009

• Nave, R. "interaction of radiation and matter." Nave, R. "interaction of radiation and matter." hyperphysics hyperphysics educationeducation. 5 Feb 2009 . 5 Feb 2009 <http://hyperphysics.phy-astr.gsu.edu/hbase/mod3.html#c5>. <http://hyperphysics.phy-astr.gsu.edu/hbase/mod3.html#c5>.

The EndThe End