The document discusses how a glass prism refracts white light into a visible spectrum. It explains that when white light enters a prism, the different wavelengths of light are refracted by different amounts due to dispersion. This causes the light to separate into the colors of the visible spectrum from red to violet. An experiment is described where a beam of white light passes through a prism, producing a spectrum that can be used to measure the angles of refraction and dispersion.