Color Recognition

Description: Students identify the actual colors of objects bathed in monochromatic light.

Objective: To show how space observatories make use of monochromatic filters to collect data on the color of objects in space.


Materials:

Indoor/outdoor colored flood lamps (red, green, blue)
Lamp base
Various colored objects (apple, banana, grapes, pear, plum, etc.)
Dark room

Procedure:

1. Darken the classroom and turn on the red lamp.

2. Hold up the colored objects one at a time. Ask students to make notes as to how bright or dark the objects appear in the red light.

3. Turn off the red light and turn on the green light and repeat with the same objects. Repeat again, but this time use the blue light.

4. Turn on the room lights and show the students the actual colors of the objects.

5. Challenge the students to identify the colors of new objects. Show them the unknown objects in the red, green, and then blue lights. By using their notes, the students should be able to determine the actual colors of the objects.

6. Hold up a Granny Smith or Golden Delicious apple to see if the students can correctly judge its actual color or will instead jump to an erroneous conclusion based on shape.

Discussion:

Astronomical spacecraft working in the visible region of the electromagnetic spectrum, such as the Hubble Space Telescope, collect images of stars and galaxies in various colors. Color filters rotate into the light path so that the detector sees one color at a time. The image in each of these colors is transmitted to Earth as a series of binary numbers. Image processing computers on Earth combine the data to reconstruct a multi-colored image. Telescopes also use filters that pass only a very narrow range of wavelengths. This technique allows the astronomer to obtain an image that shows the light from just one element such as helium.

This activity demonstrates the color imaging process. By examining various objects in red, green, and then blue light, the students

Next page Teacher Resources


Last modified prior to September, 2000 by the Windows Team

The source of this material is Windows to the Universe, at http://windows2universe.org/ from the National Earth Science Teachers Association (NESTA). The Website was developed in part with the support of UCAR and NCAR, where it resided from 2000 - 2010. © 2010 National Earth Science Teachers Association. Windows to the Universe® is a registered trademark of NESTA. All Rights Reserved. Site policies and disclaimer.