PURPOSE: Demonstrate absorption spectrum of glass doped with various chemicals.
DESCRIPTION: A bright point source with condenser lens and iris is focused by a 10 cm focal length cylindrical convex lens onto a slit, which is in turn focused onto a distant screen by a 20 cm focal length spherical convex lens. A white light spectrum is obtained by inserting an equilateral prism just after the spherical lens. A sample of glass doped with a chemical is placed in the beam just before the slit. The system now shows the absorption spectrum of the glass.
The color of the glass is not an unsaturated color formed by a narrow bright band superposed on a continuum, but rather is a negative color that is achieved by removing other wavelengths.
REFERENCES: (PIRA unknown.)
EQUIPMENT: Bright point source with condenser lens and iris, 10cm focal length cylindrical convex lens, slit, 20cm spherical convex lens, and prism, with holmium oxide, neophane, and didymium glass samples.
SETUP TIME: 5 min..
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