optics.gif (6954 bytes)

INTERFERENCE IN A SOAP FILM








EQUIPMENT
    redball.gif (326 bytes) Lens (35 cm)
    redball.gif (326 bytes) Plastic Cylinder
    redball.gif (326 bytes) Soap Solution
    redball.gif (326 bytes) 6 Volt Light




NARRATIVE
            A soap film held vertically will form a wedge thicker at the bottom. When this wedge is illuminated with white light, particular wavelengths interfere constructively at particular thickness of the soap film wedge. The result is bands of color being reflected from the entire wedge. Place the plastic cylinder in the soap solution and place it in the holder so that reflected light passes through the converging lens and onto the screen.