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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:

  • Ultraviolet (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 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?

  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?

worksheet

Worksheet: Things that Glow in the Dark

Things that glow.docx

assessment

Assessment

Assessment of Lesson 8.docx

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.