Ultraviolet (UV) radiation has wavelengths shorter than visible light. It is emitted by the sun and can be produced artificially. UV is divided into UVA, UVB, and UVC. While overexposure can harm health, moderate UV has benefits like vitamin D production. UV is used in applications like disinfection, lithography, and forensic analysis due to its ability to cause chemical reactions and fluorescence.

2. INTRODUCTION
 Ultraviolet(UV) is an electromagnetic radiation with
wavelength from 10nm to 400 nm .shorter than that of
visible light but longer than X-ray.
 These rays are invisible to human eye.
 Natural source of UVR is Sun.
 Artificially can be produced by electric arcs & specialised
lights such as Mercury Vapour lamp,tanning lamp & black
lights.
 Long wavelength UV radiation can cause chemical
reaction & cause many substances to glow or flouresce.
 Also the Biological effect of UV are greater than simple
heating effect ,Hence many practical application of UV
radiation derive from it’s interaction with organic
molecules.

4. DISCOVERY
 “Ultraviolet” means “Beyond violet” (Latin-
ULTRA-BEYOND). It was discovered in
1801 by German Physicist Johann Wilhelm
Ritter & Vaccum UV (radiation below
200nm),strongly absorbed by air was
discovered by German Physicist Victor
Schumann in 1893

5. Subtypes
 The electromagnetic spectrum of ultraviolet
radiation (UVR), defined most broadly as 10–400
nanometers, can be subdivided into a number of
ranges.
 ULTRAVIOLET A(UVA) 315nm-400nm
 ULTRAVIOLET B(UVB) 280nm-315nm
 ULTRAVIOLET C(UVC) 100nm-280nm
 NEAR ULTRAVIOLET (NUV) 300nm-400nm
 MIDDLE ULTRAVIOLET (MUV) 200nm-300nm
 FAR ULTRAVIOLET (FUV) 122nm-200nm

8. Solar ultraviolet
 The Sun emits ultraviolet radiation at all wavelengths,
including the extreme ultraviolet where it crosses into X-
rays at 10 nm.
 Sunlight in space at the top of Earth's atmosphere is
composed of about 50% infrared light, 40% visible light,
and 10% ultraviolet light, for a total intensity of about
1400 W/m2 in vacuum.
 However, at ground level sunlight is 44% visible light,
3% ultraviolet (with the Sun at its zenith), and the
remainder infrared.
 Sun's UV, almost entirely in the shorter UV wavelengths,
when the Sun is highest in the sky (zenith). Of the
ultraviolet radiation that reaches the Earth's surface,
more than 95% is the longer wavelengths of UVA, with
the small remainder UVB. There is essentially no UVC.

9. ARTIFICIAL SOURCES
 BLACK LIGHT
 SHORT-WAVELENGTH UV-LAMP
 GAS DISCHARGE LAMP
 UV-LEDS
 UV-LASERS

13. ULTRAVIOLET LIGHT FROM
STARS
 The Lyman-Alpha Mapping Project (LAMP)
onboard the Lunar Reconnaissance Orbiter can
peer into permanently shaded craters on the moon
by sensing the faint reflections of UV light coming
from distant stars.
 AURORAE
 JUPITER’S AURORA

14. ULTRAVIOLET ASTRONOMY
 Since the Earth's atmosphere absorbs much of the
high-energy ultraviolet radiation, scientists use
data from satellites positioned above the
atmosphere, in orbit around the Earth, to sense
UV radiation coming from our Sun and other
astronomical objects.
 Scientists can study the formation of stars in
ultraviolet since young stars shine most of their
light at these wavelengths.

16. THE OZONE "HOLE"
 Chemical processes in the upper atmosphere can
affect the amount of atmospheric ozone that
shields life at the surface from most of the Sun's
harmful UV radiation.
 Each year, a "hole" of thinning atmospheric ozone
expands over Antarctica, sometimes extending
over populated areas of South America and
exposing them to increased levels of harmful UV
rays.

18. WHY HUMAN EYE’S CAN’T PERCEIVE
UV?
 Because the lens of human eye blocks
most radiation in wavelength range of
300-400nm ,shorter wavelength are
blocked by Cornea.
 Neverthless,the photoreceptors of the
Retina are sensitive to near UV and
people lacking a lens,perceive near UV
as whitish blue or whitish Violet.

19. HARMFUL EFFECT & BENEFITS
OF UVR
 The impact of ultraviolet radiation on
human health has implications for the
risks and benefits of sun exposure, and
is also implicated in issues such as
fluorescent lamps and health.
 Getting too much sun exposure can be
harmful, but in moderation is beneficial

20. BENEFITS
 Production of vitamin D
 Improvement of mood
 Incresed energy
 Causes skin condition like Rickets,Vitiligo,Psoriasis
 Higher vitamin D tend to have lower rate of DIABATES,HEART
DISEASES,STROKES, & LOW BLOOD PRESSURE.
 Melanin is an excellent photoprotectant that
absorbs both UVB and UVA radiation and dissipates
the energy as harmless heat, protecting the skin
against both direct and indirect DNA damage.

21. HARMFUL EFFECT
 Impact on Skin,Eye,
& Immune System

22. Applications
 Because of its ability to cause chemical reactions
and excite fluorescence in materials, ultraviolet
radiation has a number of applications as follows.
 Air purification
 Evolution of enzymes and proteins

23.  13.5 nm: Extreme ultraviolet lithography
 30–200 nm: Photoionization, ultraviolet photoelectron
spectroscopy,
 standard integrated circuit manufacture by photolithography
 230–365 nm: UVID,
 label tracking, barcodes
 230–400 nm: Optical sensors, various instrumentation
 240–280 nm: Disinfection, decontamination of surfaces and
water (DNA absorption has a peak at 260 nm)
 200–400 nm: Forensic analysis, drug detection
 270–360 nm: Protein analysis, DNA sequencing, drug
discovery
 280–400 nm: Medical imaging of cells
 300–320 nm: Light therapy in medicine
 300–365 nm: Curing of polymers and printer

24. Source: WIKIPEDIA
NASA science
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