Q: Is a reflectance always a positive real number? ¶
A: Yes.
Q: Is a reflectance the fraction of electromagnetic power reflected from a specific sample? ¶
A: Yes, while reflectivity is a property of the material itself, which would be measured on a perfect machine if the material filled half of all space.
Q: Is a reflectance uniform? ¶
A: Yes, radiation is reflected in all angles equally or near-equally.
Q: Is a reflectance an important concept in the fields of optics? ¶
A: Yes, and solar thermal energy, telecommunication and radar.