Final answer:
A spectroscope or spectrometer is the device that separates light into its component wavelengths using a narrow slit, a collimating lens, a prism or grating, and a detector like a CCD.
Step-by-step explanation:
A device that can separate light into its different wavelengths is known as a spectroscope or spectrometer. The process it uses is called spectroscopy. When light enters the spectroscope through a narrow slit, it is collimated by a lens into a beam of parallel rays. This collimated light then passes through a prism (or grating) where it is dispersed into its component wavelengths, forming a spectrum. Different wavelengths of light are bent by different amounts as they pass through the prism, causing them to spread out into a rainbow of colors. A second lens focuses these different colors onto a CCD (charge-coupled device) or other detector, allowing astronomers and scientists to analyze the spectrum and learn about the composition and other properties of the light source.