Final answer:
The ability of a substance to reflect light is called its reflectivity. Smooth, shiny surfaces like mirrors can reflect over 90% of light, and they are crucial to the function of optical devices, which use properties of light like reflection and refraction. Total reflection can be realized through total internal reflection, a refraction-related phenomenon.
Step-by-step explanation:
The ability of a substance to reflect light is generally termed its reflectivity or reflectance. This property varies depending on the substance, with smooth and shiny surfaces like mirrors typically having high reflectivity. A highly reflective surface can reflect over 90% of the light that falls on it, making it useful in a variety of applications, including optical instruments such as telescopes and eyeglasses.
Mirrors and other reflective surfaces operate on the concept that when light strikes them, it is bounced back into the environment, following the law of reflection. This behavior of light - which also includes refraction, or the bending of light when it passes from one medium to another - is essential for the functioning of many optical devices.
Furthermore, it's interesting to note that total reflection can be achieved through a phenomenon associated with refraction called total internal reflection. This occurs when light traveling within a denser medium is incident at an angle larger than the critical angle for that medium and is completely reflected back into the medium, rather than refracted out.