Objective: To study the range of colors in the visible spectrum.
Procedure: Method 1
1. Make an opaque screen approximately 25 cm square from a piece of cardboard, poster board, or wood. Cut a 5 cm-diameter hole out of the middle. Tape two pieces of opaque paper or aluminum foil over the hole so that there is a vertical gap between them that is no wider than 1 mm. Stand the screen upright between two books.
2. Arrange the slide projector, opaque screen, prism, and projection screen as shown in the diagram. Darken the room. Aim the projector's beam at the slot in the opaque screen and adjust the projector so that the light does not extend around the edges of the opaque screen.
3. Slowly rotate the prism until the narrow slot of light disperses the visible
spectrum. Depending upon the exact alignment, the spectrum may fall on a wall rather than on the screen. Adjust the setup so that the spectrum is displayed on the projection screen.
Procedure: Method 2.
1. For this method, you must obtain a piece of holographic diffraction grating--a grating produced by accurate holographic techniques. See page 31 for the source of the grating. Note: Method 2 will not work well with a standard transmission grating.
2. Make an opaque screen from two pieces of dark paper or other opaque material. Place the pieces on the overhead projector stage so that there is a narrow slot no wider than 2 mm where light can come through.