What is the definition of an incident ray?

An incident ray is defined as a ray that travels towards an object or a surface. This is a fundamental concept in optics, particularly when discussing how light interacts with different surfaces. When light reaches an object, the behavior of the incident ray—whether it gets reflected, refracted, or absorbed—depends on the properties of the object it encounters.

In the context of light interactions, the incident ray is the one approaching the surface before any interaction occurs. For example, when light strikes a mirror, the ray that comes in contact with the mirror first is the incident ray. Understanding this concept is essential when studying optics, as it sets the stage for exploring other phenomena such as reflection and refraction.