PBL Project Page

Driving Question

What causes the colors of a rainbow to appear when you look at a light bulb through a pair of rainbow glasses?

Introduction:

Diffraction glasses use rainbow glasses, a red laser, and Incandescent or other white-light ray box to separate the colors that make up white light, like a triangular prism. If you look at a bright light and put your hand between the glasses and the light, you would see your hand defract.

Materials:

♦ Rainbow glasses

♦ Monochromatic light source

♦ Red laser

♦ Meter stick

♦ Incandescent or other white-light ray box

♦ Protractor

♦ Transmissive diffraction grating (300–600 lines/mm)

Procedure:

For this project, first, I have to turn off the lights in the room to do the experiment. I have someone (or myself)

hold the flashlight facing in a certain direction. Then, I put on the diffraction glasses and the light becomes diffracted

and looks like its a color prism.

Scientific Principle:

Diffraction

Diffraction refers to various phenomena which occur when a wave encounters an obstacle.

Huygens principle

Every point on a wave-front may be considered a source of secondary spherical wavelets which spread out in the forward direction at the speed of light. The new wave-front is the tangential surface to all of these secondary wavelets.

Diffraction grating

Diffraction grating is an optical component with a periodic structure which splits and diffracts light into several beams travelling in different directions.