Question

an optical ____ is a device that refracts light rays into a spectrum, or the colors that make up light.

answer input:
spelling counts but capitalization doesnt.

Explanation:

In physics (a subfield of Natural Science), a prism is an optical device that refracts light to separate it into its constituent colors (spectrum) due to the different wavelengths of light being refracted at different angles.

Answer:

prism