Final answer:
Reflectivity is the term used to describe the fraction of incident light that a body reflects, and it is distinct from absorptivity or emissivity. Reflectivity is an important property in physics that affects how energy is managed and utilized in various scientific applications.
Step-by-step explanation:
The fraction of incident light that a body reflects is known as its reflectivity. This is characterized by the intensity reflection coefficient, which is the ratio of the intensity of the reflected wave to that of the incident, or transmitted, wave. In contrast to absorptivity, which is the fraction of light that a material absorbs, and emissivity, which describes how effectively a material emits radiation, reflectivity specifically measures the proportion of incident light that is bounced back from the surface of an object. Surfaces with high reflectivity are poor absorbers of light and therefore do not model a perfect blackbody well; instead, absorptive surfaces are better models because they absorb most of the incident radiation.
Environmental factors such as changes in reflectivity can influence how much energy enters Earth's system. Reflectivity plays a crucial role in various scientific and engineering applications where managing light interaction with materials is important.