A spectroscope separates light into its component wavelengths by using a prism or diffraction grating. When light passes through a prism, it is refracted, or bent, at different angles depending on its wavelength. Shorter wavelengths, such as blue and violet light, are refracted more than longer wavelengths, such as red and orange light. This causes the light to be spread out into a spectrum of colors.

A diffraction grating works in a similar way, but instead of using a prism, it uses a series of parallel slits. When light passes through a diffraction grating, it is diffracted, or spread out, into a spectrum of colors. The diffraction grating produces a more precise spectrum than a prism because it spreads the light out into a wider range of wavelengths.

Spectroscopes are used to study the composition of light from stars and other astronomical objects. They are also used to study the composition of materials on Earth, such as minerals and chemicals.