Which term describes the amount of light reflected by an object?

• A. Absorptivity
• B. Reflectivity
• C. Transmittance
• D. Brightness

Answer: (B)

Reflectivity describes how much light bounces off a surface. When light hits an object, part is reflected, part absorbed, and if the material isn’t opaque, part can also be transmitted. Reflectivity is the ratio of the reflected light to the incident light, often expressed as a value from 0 to 1. In opaque materials, almost all light is either reflected or absorbed, so reflectivity and absorptivity together approximate the total interaction with light. In transparent materials, transmission becomes significant, so reflectivity is just one part of the picture. Brightness, by contrast, is a perceptual effect that depends on illumination and viewing conditions rather than a fixed physical property. A mirror has high reflectivity, while a black matte surface has low reflectivity. So the term that describes the amount of light reflected by an object is reflectivity.