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. For Unit 5: Geometric Optics, the wave nature of light can be ignored, that will be discussed in Unit 6: Waves, Sound, and Physical Optics. 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 used more in Lessons 5.2 and 5.4.