Glass Prism - Discover Science This glass prism is made using optical glass and will demonstrate that white light is made up of the colours of the rainbow. This is known as a spectrum. Sir Isaac Newton in the 17th century was the first to prove that white light was in fact made up of different colours. He used a glass prism in his experiments. Glass prism dispersionHow does it work? When sunlight passes through a piece of glass with parallel sides, such as a window, the light emerges in the same direction that it entered the glass. When sunlight passes through glass at an angle, such as a prism, the light beam is bent or refracted. Each wavelength of light within bends at a slightly different angle (the light with shorter wavelengths bends less than the light with longer wavelengths) so that the beam is spread out as it passes through the prism, to be displayed on the other side as a spectrum of colours. The spreading out of the beam of light is known as dispersion.Put the prism on a window ledge for a rainbow of light in your room.Size: 50mm long. Each face 28mm. Corners are ground for safety.