What is the difference between reflectance and reflectivity, and how do they relate to each other in the context of light and surface interactions?
Reflectance refers to the amount of light that is reflected off a surface, while reflectivity is a measure of how efficiently a surface reflects light. Reflectance is a property of the surface, while reflectivity is a physical property of the material. In the context of light and surface interactions, reflectance and reflectivity are related in that they both describe how much light is reflected off a surface, but reflectivity specifically quantifies the efficiency of that reflection.