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).

Materials


Per pair of students:
  • Ultravioloet (UV) LED, two coin batteries
General Supplies:
  • Paper fasteners, tape, hook-up wire, strippers, tape, rubber bands
  • Fluorescent markers (yellow hi-lighters), cardstock in assorted colors, small boxes
  • craft materials


Procedure


1. Things that glow: Demonstrate how to light up a secret message using a UV LED. If possible, have someone turn off the lghts so the effect is more dramatic. Conduct a discussion about what is happening:
  • What is making this glow?
  • How could you use this idea?
2. 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. 

3. 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?

Troubleshooting


If the secret message or image glows but is too dim, some things to try are: 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 Multimeter -- click here to explore further.

Worksheet: Things that Glow in the Dark

Things that glow.docx
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Assessment

Assessment of Lesson 8.docx
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