Ultraviolet Rays What are ultraviolet rays A type

Ultraviolet Rays

What are ultraviolet rays? • A type of electromagnetic wave with a shorter wave length. They are invisible to the naked eye, and typically come from the suns radiation to the earth. • Ultraviolet means beyond violet, and violet is the color of the shortest wavelength of visible light.

The Discoverer l Johann Wilhelm Ritter l l l Dec 16 1776 - Jan 23 1810 German chemist and physicist Died at a young age, they believe it was because he used his own body in his electrical experiments.

How did he discover it? n n n After hearing of Hershel's discovery of Infrared light, and it being non visible, he decided to conduct experiments as well. Ritter realized that silver salts/silver chloride darkened when it was exposed to sunlight He called them de-oxidizing rays (taking the effects of oxygen away)

Frequency and Wavelength l 750 -30, 000 THz = frequency range l 400 -10 nm = wavelength

How is it used? • In medicine it kills bacteria and viruses • Disinfecting water, food processing • Sun tanning • security (credit cards, passports, drivers license) • Black lights • Fire Detectors • Sterilization • Lasers • Determining substance abuse in public places A bird shows up on many Visa cards when placed under UV lights

Does it have any effects? l l l Therapeutic purposes (such as treating skin disease) It is the biggest cause for skin cancer. Ages skin faster Trigger allergic reactions Long exposures can result in blindness over time Sunburns Malignant melanoma-one of the three skin cancers you can get.

Interesting… • Ultraviolet tattoo • Suntans come from after they have killed your skin cells, and damaged others. • On average around 70 80% of a person’s life time exposure to the sun occurs by the age of 18. • Approximately 80 - 85% of UV rays pass through clouds. • Cat urine, and scorpions both glow in black light Does this work? You can buy it on ebay…

sources http: //en. wikipedia. org/wiki/Ultraviolet_Ray s l www. spacebuffs. com/glossary l Google images: UV rays l information from the BG health department www. hvbg. de/e/bia/fac/strahl/uv_str_e. pdf l http: //simun. inspiringteachers. com/custom 2. html l