Chemistry

Black Light Experiments



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Bring an eerie glow to your classroom with a black light. Turn off the lights, turn on the black light and watch for the glow. Because black lights glow a purplish black and give off an ultraviolet light, they cause anything with the synthetic substance, phosphor, to glow. Phosphor converts the energy found in the ultraviolet radiation emitted by the black light into visible light. Black lights are fascinating to most kids, allowing teachers to captivate student's attention with black light experiments in the classroom.

Cleanliness and the spread of germs

Simulate germ-fighting with your students. Have students cover their hands, front and back and around the nails, with a germ-simulating powder like Glo Germ. Turn on the black light and have students hold their hands underneath the light so they can see the "germs" on their hands. Have students wash their hands for five seconds and check them again. Ask them to wash their hands for another five seconds and check again. Repeat the hand-washing two more times, fifteen seconds the first time and twenty seconds the second time. Hold a class discussion on the need to wash hands thoroughly to avoid spreading germs. For more details and ideas, check here.

Shiny minerals 

Everything that glows isn't gold. Because of impurities, other rocks will glow when they react to your black light. Bring in several rocks for around the school. Include talc, calcite, gypsum, agate, quartz, or amber in the mix. Keep a record of which rocks glow and which do not. The electrons in the rocks absorb the black light energy which shows to the observers in a visible light showing brilliant colors. 

Highlighting it

Cause an unusual glow of your own. Pour water in three baby food jars. Cut open a pink, yellow and blue fluorescent highlighters. Drop one into each jar of water and let the water absorb the colors. Put lids on the jars. Turn off the lights and turn on the black light. Hold each jar up to the black light one at a time. Compare the ways the different colors glow. Draw conclusions from your data.

Glowing greens

Most of us think chlorophyll is green, but under the black light, a transformation takes place. Chop up a cup of spinach and place it in a blender. Add two ounces of rubbing alcohol and blend them. Strain the liquid into a jar by pouring it through a coffee filter. Put a lid on the jar. Hold the jar filled with chlorophyll next to the black light. Things are not always what they appear under a black light!

Testing, testing

Encourage students to bring objects to school that they think might respond to the black light. Everyday items might surprise them. For example, teeth will glow if you have brushed them with a whitener. Try regular Vaseline. Try laundry chemicals, vitamins, club soda and more. Bring in your overripe banana and compare it to a bruised apple. Let the kids have fun guessing which items will glow and which will not; then turn out the lights and learn the truth together. 

Black lights are fun and entertaining but they can teach your students too. Buy one today and make your science class glow.

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ARTICLE SOURCES AND CITATIONS
  • InfoBoxCallToAction ActionArrowhttp://www.bam.gov/teachers/activities/epi_4_hand_wash.pdf