Intensive and extensive properties
Physical properties of materials and systems are often described as
intensive and extensive properties. This classification relates to the dependency of the properties upon the size or extent of the system or object in question. The distinction is based on the concept that smaller, non-interacting identical subdivisions of the system may be identified so that the property of interest does or does not change when the system is divided or combined. An
intensive property is a
bulk property, meaning that it is a physical property of a system that does not depend on the system size or the amount of material in the system. Examples of intensive properties are the temperature, refractive index, density and the hardness of an object. No matter how small a diamond is cut, it maintains its intrinsic hardness. By contrast, an
extensive property is one that is additive for independent, noninteracting subsystems. The property is proportional to the amount of material in the system. For example, both the mass and the volume of a diamond are directly proportional to the amount that is left after cutting it from the raw mineral.