StellarLight Rays
Light rays are used to model light as a particle. In this case, light is modeled as a bunch of photons that travel in a single direction. Note that while light does also have a wave nature, this unit will only treat them as particles. A common source of light rays are lasers, which shoot light in a straight line which can be modeled as a ray.
Ray Diagrams are used to show where the light travels. It uses arrows that start where the light originates and points in the direction the light travels. This will be more useful when discussing images created by lenses or mirrors.