Colored Shadows

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In this optics activity, learners discover that not all shadows are black. Learners explore human color perception by using colored lights to make additive color mixtures. With three colored lights, learners can make shadows of seven different colors. They can also explore how to make shadows of individual colors, including black. Use this activity demonstrate how receptors in the retina of the eye work to see color.

Quick Guide

Preparation Time:
10 to 30 minutes
Learning Time:
5 to 10 minutes
Estimated Materials Cost:
$5 - $10 per group of students
Age Range:
Ages 6 - 18
Resource Types:
Activity, Demonstration, Exhibit
Language:
English

Materials List (per group of students)

  • White surface. (A white wall, white posterboard, or white paper taped to stiff cardboard works well. Do not use a beaded or metal slide projection screen.)
  • Red, green, and blue lightbulbs or floodlamps, one of each color. Sylvania #11 colored lightbulbs or General Electric Dichrocolor Dichroic Floodlamps (150 watt) work well. We have even obtained excellent results with clear-colored Christmas tree lights. Smaller or dimmer bulbs are fine for tabletop use by a few students, but larger, brighter bulbs allow a larger-scale demonstration.
  • 3 light sockets of any type or arrangement that will get the light from the three bulbs simultaneously directed onto the same area of a white surface.
  • Any solid object such as a pencil, ruler, correction fluid bottle, finger, etc.
  • Adult help

Keywords

Subjects

  • Life Sciences
    • Human Body
      • The Brain and Nervous System
    • Human Senses and Perception
      • Vision
      • Perception
  • Physical Sciences
    • Vibration and Waves
      • Light and Optics
    • Light and Optics
      • Electromagnetic Spectrum
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations

Audience

To use this activity, learners need to:

  • see
  • see color

Learning styles supported:

  • Involves hands-on or lab activities

Other

This resource is part of:

Access Rights:

  • Free access

By:

Rights:

Funding Sources:

  • National Science Foundation
  • California Department of Education
  • NEC Foundation of America