Energy systems
ElectroCity
8. Things that Glow in the Dark
Overview
Students discover how an ultraviolet (UV) LED can make a fluorescent pattern glow in the dark. Then they learn about how different forms of radiation are related, including ultraviolet, visible and infrared light.
Advance Preparation
- Make a simple circuit with an ultraviolet (UV) LED and two coin batteries, and use it to light up a “secret message.” Save the components for a classroom demonstration. See a video and diagrams showing how. Make a chart showing the circuit diagram.
- Make a chart labeled Different Forms of Radiation, with the headings “Infrared”, “Visible Light” and “Ultraviolet”. Leave space for additional headings.
- Photocopy worksheet and assessment (downloadable at bottom of page).
Procedure
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Things that glow: Demonstrate how to light up a secret message using a UV LED. If possible, have someone turn off the lights so the effect is more dramatic. Conduct a discussion about what is happening:
- What is making this glow?
- How could you use this idea?
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Make something that glows in the dark: Provide materials and time for students to make their own images and messages that can glow in the dark.
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Different forms of radiation: This lesson uses ultraviolet (UV) light and the next one will focus on infrared (IR) light, so this is a good opportunity to discuss different forms of light and of other kinds of radiation (see a video). Ask students:
- What do you know about infrared light, visible light and ultraviolet light ?
- What is the effect of each kind on us?
- What can each type be used to do?
Chart their observations. Explain that these are all forms of radiation, and ask:
- What other forms of radiation are there?
- How is each type of radiation produced?
- What can it be used for?
Worksheet: Things that Glow in the Dark
Assessment
Troubleshooting
If the secret message or image glows but is too dim, some things to try are:
- Make sure there are two coin batteries in series (see a video)
- Use a different background color (see a video)
- Turn off the lights or find a darker place.
If the UV LED doesn’t come on at all, check to see that the batteries are stacked correctly (see a video). To learn more about this issue, you can use the Digital Multi meter – click here to explore further.