What describes the path of a single photon of light?

The path of a single photon of light is best described as a ray. This term is commonly used in optics to refer to the straight-line path along which light travels. In this context, a ray represents the direction and path of light propagation, illustrating concepts such as reflection, refraction, and lens effects in optical systems.

Understanding light as rays helps in visualizing how light interacts with various materials and surfaces, facilitating practical applications in designing eyewear, lenses, and other optical devices. While light also exhibits wave-like properties and can be thought of in terms of wave functions or particles, describing the trajectory of a single photon as a ray helps simplify the understanding of its travel in many optical contexts.