Home > Intensive quantity

1 Properties

Let there be one piece of substance of amount n and another piece of substance of amount m. Let V be an intensive variable. The value of variable V corresponding to the first substance is V(n), and the value of V corresponding to the second substance is V(m). If the two pieces are put together, forming a substance of amount n+m, then the value of their intensive variable should be

,

which is a weighted mean. Further, if then , i.e. the intensive variable is independent of the amount. Note that this property holds only as long as other variables on which the intensive variable depends stay the same.

The ratio of two extensive quantities is an intensive quantity. For instance, density (intensive) is equal to mass (extensive) divided by volume (extensive). For a more subtle example, consider the following: Pressure is force divided by area. But neither force nor area are either extensive or intensive. However, force multiplied by length is work, which is extensive, and area multiplied by length is volume, which is extensive. Therefore, pressure actually is a ratio of two extensive variables—work/volume—and so it is intensive.

The reciprocal of an intensive quantity is itself intensive.

2 Examples

Examples of intensive physical quantities are

• density
• temperature
• pressure
• specific heat
• voltage ( electric potential)
• speed

The following variables are neither extensive nor intensive: length, timeFor alternate uses of "time", see Time (disambiguation). Time quantifies or measures the interval between events, or the duration of events. Time has long been perceived as a dimension in which each event has a definite (but not necessarily unique) positi, areaThis article explains the meaning of area as a Physical quantity. Article area (geometry) is more mathematical. Area is a quantity expressing the size of a region of space. Surface area refers to the summation of the areas of the exposed sides of an objec, forceIn physics, a net force acting on a body causes that body to accelerate; that is, to change its velocity. The concept appeared first in the second law of motion of classical mechanics. It is usually expressed by the equation F m · a where F is the force,, angular momentumIn physics, angular momentum intuitively measures how much the linear momentum is directed around a certain point called the origin; the moment of momentum. Since angular momentum depends upon the origin of choice, one must be careful when discussing angu.