Quality (physics)

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This article is about quality in the physical sense. For other uses, see quality (disambiguation).
Not to be confused with Physical quantity.

In physics, quality has several different meanings.

[edit] Thermodynamics

The quality of a fluid is the percentage of mass that is vapor; i.e. saturated vapor has a "quality" of 100%, and saturated liquid has a "quality" of 0%. For instance, in analysis of the Rankine cycle the quality of a multi-phase working fluid would be understood to imply this definition.

An alternate meaning of quality of heat may be used to describe the availability of thermal energy as dictated by the second law of thermodynamics. Also see exergy efficiency.

[edit] Harmonics

In response theory, the quality of an excited system is related to the number of excitation frequencies to which it can respond. In the case of a homogeneous, isotropic system, the quality is proportional to the full width at half maximum.

This sense of the phrase is the primogenitor of the usage of the word in music theory. In music theory, quality is the number of harmonics of a fundamental frequency of an instrument (the higher the quality, the richer the sound).

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