A spectrograph is an instrument used in scientific research to analyze the composition of materials based on their electromagnetic spectrum. Spectrographs work by dispersing light into its component wavelengths using a diffraction grating or prism, allowing researchers to identify the specific wavelengths of light emitted or absorbed by a sample. This information can be used to determine the chemical composition, temperature, density, and other properties of the material being studied. Spectrographs are commonly used in fields such as astronomy, chemistry, and environmental science for a wide range of applications including identifying elements in stars, analyzing the composition of atmospheric gases, and studying the properties of molecules.