OBJECTIVES:
VOCABULARY:
MATERIALS:
BACKGROUND:

Emphasize that this segment concentrates on visible light which is a part of the electromagnetic wave spectrum. Review how light carries energy in tiny packets of electromagnetic radiation called photons. Light travels at 296,000 meters per second or 186,000 miles per second and doesn't need a medium to travel in. All colors of light travel at the same speed, but they have different wave frequencies (short and long waves).

Look at the illustration to the right and notice the direction of the shadow is away from the source. During midday it would be the shortest, and in afternoon it would be on the opposite side.

Light can be reflected or refracted. In reflection, light bounces off a surface and is diffused. Light travels in a straight line and refraction is the bending of this light. The light breaks up into different frequencies therefore causing a rainbow or a "broken" look.

This activity demonstrates different components of refracted light. If students do not know the light spectrum, give them the following pneumonic device to help them remember. ROY G. BIV = red, orange, yellow, green, blue, indigo and violet.

Light is bent twice when it passes through a prism and the separation of color is quite noticeable - a rainbow. The prism separates the frequencies of light, so a rainbow appears. What colors can you separate from the white light? If your classroom has bright sunlight that is a good source of light; otherwise use a flashlight. Light must be directed toward the prism at the correct angle in order to get a rainbow.

PROCEDURE:
  1. Read Light Magic. Make sure the students understand the story. You may want to refer back to this story when you are doing the lab. If you have time at the end, you may want to refer back to the book.

  2. Discuss with students what a prism does to light. It refracts. Go over that rainbows are only created when there is refraction.
  3. Notice that you have 3 different types of prisms. One of them is a right angle prism. Go over with student the difference. Which on is longer? Which is thicker? Ask them to describe the prisms.
  4. Tell them they are going to do an experiment. Do prisms make better rainbows inside or outside. Give them a flashlight and turn off the lights and try to make rainbows on the ceiling, lab tables, or floor. Make sure they look at all the different prisms. Remind children that they should see "Roy G. Biv." Suggest to students that they move the angle of the light. Does that make a difference? Which way produces the strongest color? Do they always see "Roy G. Biv" every time they make a rainbow. Keep asking questions to direct their learning? You do not need an answer, just to focus their observation.
  5. Then go outside and use natural light. If the day is overcast it may be difficult to get a rainbow outside. But then, that should be part of the discussion. Ask them why there is no rainbow.
  6. Go back inside and discuss what they saw. Let them decide which made the best rainbow of the 3 shapes and where did they create the best rainbow. Ask questions again about Roy G. Biv. Please note repetition is important.
  7. If you have time, have students color the ROY G BIV Rainbow.