Educate
May. 08, 2015

Make a UV Detector

by Lawrence Hall of Science

Click to enlarge images
In this activity from Lawrence Hall of Science, you'll use tonic water to detect ultraviolet (UV) light from the sun.
 
Be sure to share what you've learned about the sun and UV light during Science Friday's Science Club, using the hashtag #ExplainTheSun.
 
Age Level: 7 and up 
 
Time
Preparation: 5 minutes 
Activity: 5 minutes
Cleanup: 5 minutes
 
Materials
• two clear cups (plastic or glass)
• tonic water 
• tap water
• flashlight
• black piece of paper
• pen
• two index cards
• tape
• hardcover book 
 
Step 1 
Use your pen and paper to make two signs labeled “Tonic Water” and
“Tap Water.” Tape these signs next to each other at the top of the
sheet of black paper, and tape the black paper to a hardcover book. Stand the book upright and place one cup under each sign. 
 
Step 2 
Fill each cup to the brim with the kind of water noted on the label.
While you’re indoors, shine a bright flashlight at both full cups.
Do you see any color difference between the cups? 
 
Step 3
Bring your black piece of paper outside, in full sunlight. Prop up the book so that the paper is vertical. Place the same two cups in front of the paper. Now what colors are the two liquids? 
 
What's Going On?
We can see visible light emitted by the sun. But the sun also emits light we can’t see, including UV light. Quinine is a substance found in tonic water that is sensitive to UV light. It can absorb UV light that we can’t see and then re-emit visible blue light that we can see. This process of converting ultraviolet into visible light is called fluorescence. When you shone a flashlight at the cups of water indoors, the tonic water did not fluoresce and glow blue. That’s because flashlights and everyday household lights do not emit a significant amount of UV light.
 
Examples of Fluorescence 
 Fluorescence is common in rocks and minerals. This image shows mineral specimens that are fluorescing. Some minerals appear a different color than others because of the different fluorescent elements present in each mineral. 
 
 
This activity is featured in DIY Sun Science, an iPhone/iPad app that allows you to investigate the Sun at home, at school, or anywhere you go! Download the free DIY Sun Science app at lawrencehallofscience.org/diysunscience
 
 
 

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About Lawrence Hall of Science

The Lawrence Hall of Science, UC Berkeley's public science center, has been providing parents, kids, and educators with opportunities to engage with science since 1968. Learn more at www.lawrencehallofscience.org

The views expressed are those of the author and are not necessarily those of Science Friday.
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line 6: 		$parent = $LayoutManager::url_resolved_values{'SEGMENT.nickname'};
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line 9: 		$parent = $LayoutManager::url_resolved_values{'VIDEO.nickname'};
line 10: 	}
line 11: 	elsif($LayoutManager::url_resolved_values{'DOCUMENT.nickname'}) {
line 12: 		$parent = $LayoutManager::url_resolved_values{'DOCUMENT.nickname'}
line 13: 	}
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line 16: 		my(@books) = &Database::SelectClause('BOOK',"parent = $parent");
line 17: 		if(!@books) {
line 18: 			$parent = '';
line 19: 		}
line 20: 	}
line 21: 	
line 22: 	if(!$parent) {
line 23: 		my(@sel) = &Database::SelectClause('GLOBAL','record all ""');
line 24: 		if(@sel) {
line 25: 			$parent = 'GLOBAL.' . $sel[0];
line 26: 		}
line 27: 			$main::ENV{'reading_header'} = "FEATURED READING";
line 28: 	}
line 29: 	
line 30: 	 = '';
line 31: 	
line 32: 	if($parent) {
line 33: 		my(@books) = &Database::SelectClause('BOOK',"parent = $parent");
line 34: 		0 = 0;
line 35: 		my $dots;
line 36: 		foreach(@books) {
line 37: 			my(%data);
line 38: 			&Database::GetRow($_,'BOOK',\%data);
line 39: 			my($status,$title,$author,$url,$image,$width,$height) = &SciFri::Schema::getAmazonItem($data{'isbn'});
line 40: 			if($data{'title'}) {
line 41: 				$title = $data{'title'};
line 42: 			}
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line 44: 				$author = $data{'author'};
line 45: 			}
line 46: 			if($status eq 'ok') {
line 47: 				 .= "<div class=\"box-2x1-item box-slide\" data-href=\"$url\">";
line 48: 				 .= "	<div class=\"box-2x1-item-photo\">";
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line 51: 				 .= "		</div>";
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line 60: 			}
line 61: 		}
line 62: 	}
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line 64: 	else { $main::ENV{'reading_header'} = "RELATED READING"; }
line 65:  };
line 66: &doEval();
line 67: 1;

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