PURPOSE: Demonstrate continuous spectrum using water as the dispersing medium.

DESCRIPTION: The bright point source is used to provide a continuous white light spectrum. Light from the point source is focused by a condenser lens with iris and a 20 cm focal length cylindrical lens onto a slit. A 20 cm focal length convex lens then images the slit onto the screen through a prism consisting of an equilateral triangular plastic box filled with water. The spectrum created has less dispersion than that of a glass prism due to the smaller index of refraction of water. The spectrum of a quartz glass prism is shown at the right above for comparison.

SUGGESTIONS:

REFERENCES: (PIRA 6A42.65)

EQUIPMENT: Bright point source with condenser lens and iris, 20cm focal length cylindrical convex lens, slit, 20cm spherical convex lens, and water prism.

SETUP TIME: 5 min.