investigations using ultra-violet radiation (uvr) final

8/8/2019 Investigations Using Ultra-Violet Radiation (UVR) Final

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Figure 1: Taken from http://stargazers.gsfc.nasa.gov/


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Introduction to UV Radiationy Short wavelength in the

electromagnetic spectrum

y 3 types of UV:y UVA (315-400nm),

y UVB (280-315nm),

y UVC (200-280nm)

y Dangers of UV Radiationy Absorption in excessive amounts by:

y Eyes: snow-blindness/ photokeratitis(absorption of UVB in lens/cornea)

y Skin: Photo-aging of skin leading to

skin cancer in long termFigure 2: Taken from http://www.epa.gov/sunwise/


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Maximum permissible exposures (MPE) for UVB

and UVC radiation

Figure 3: Data for the graph obtained from lab script developed by Prof. Spyrou, University of Surrey for Level 2 - Investigations using UVR


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Scientific Theoryy Most radiation sources will have a broad spectrum

of relative spectral distribution.

y UVR of certain wavelengths have specificcorresponding calibrated detectors (radiometers)that measure radiation power irradiance

y

Beer-Lambert law predicts the irradiance decreasesexponentially with the increase in radiation absorberthickness, i.e.: I = Ioe -x, where is the absorptioncoefficient.


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General Experimental Apparatus

2cm grid onmat of 8cm by24cm

Radiometer

Detectorcorresponding

to UVR

UV Lamp (A or B or C)

Figure 5: Taken from www.seoulin.co.krigure 4: Taken from www.lot-oriel.com


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Figure 6: Taken from lab script developed by Prof. Spyrou, University of Surrey for Level 2 - Investigations using UVR

Incidentlight beam Non-

uniformintensity

of lightacross thesensor

Image showing the projected area from an incident light beam onto a sensor


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Experimental Apparatus (1)

2cm grid onmat of 8cm by

24cm

Radiometer


to UVR

UV Lamp (A or B or C)

A layer ofcling filmwith UVprotectionplaced on thedetector



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Results and Analysis (1)

UVprotection

used

Type of UV light used with its corresponding detector

UVA with

UVX-36

UVB with

UVX-31

UVC with

UVX-25

Total radiationPenetration(%)

Total radiationpenetration(%)

Total radiationpenetration(%)

No UV protection 100.00 100.00 100.00

PlasticG

oggles0.

21 0.00 0.10

Shades - Eclipse Info 99 0.21 0.00 0.05Shades - Superdrug 0.18 0.00 0.05

Tesco SPF 10 0.48 0.00 0.57 Tesco SPF 30 0.28 0.00 0.11

Piz Buin SPF 15 0.20 0.12 0.06


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Experimental Apparatus (2)

2cm grid onmat of 8cm by24cm

Radiometer


to UVR

UV Lamp (B only)

Layer(s) ofglass placedon thedetector



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Where isthe

absorptioncoefficient

of the

windowglass

= (4.60.7) cm

Results and Analysis (2)


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Conclusion & Future worky The best form of all UV protection is through suncreams.

y Darker shades prevent almost all UVB and UVCpenetration to the eye.

y In order to stay within the MPE for UVB radiation for 1000seconds, a glass of thickness 0.2cm is needed.

y The window glass has to be a tleast 21cm thick tocompletely exclude the UVB radiation.

y Future work should involve work with direct sunlight,including possible experiments with UVC light andwindow glass together.


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investigations using ultra-violet radiation (uvr) final

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