Which term is used to describe lines that represent light rays and the direction they travel?

The term used to describe lines that represent light rays and the direction they travel is "ray." In optics, a ray is a straight line that indicates the path along which light travels. This concept is foundational in the study of light behavior, such as reflection, refraction, and diffraction. Rays are visualized in optical diagrams to demonstrate how light interacts with different surfaces and mediums.

While "path" could refer to anything that an object follows, it does not specifically denote the representation of light in physics. "Line" is a more general term that does not capture the specific nature of light travel. "Vector" pertains to a quantity that has both magnitude and direction, and while light can be described using vectors in more advanced contexts, the simpler and more direct term for the representation of light in ray diagrams is indeed "ray."