Noun 1. **constant of proportionality** - the constant value of the ratio of two proportional quantities x and y; usually written y = kx, where k is the factor of proportionality

factor of proportionality
**constant** - a number representing a quantity assumed to have a fixed value in a specified mathematical context; "*the velocity of light is a constant*"
**Planck's constant**, h - the **constant of proportionality** relating the energy of a photon to its frequency; approximately 6.626 x 10^-34 joule-second
**factor** - any of the numbers (or symbols) that form a product when multiplied together. [Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.]

"In mathematics, two variables are proportional if a change in one is always accompanied by a change in the other, and if the changes are always related by use of a constant. The constant is called the *coefficient of proportionality* or *proportionality constant*.

- If one variable is always the product of the other and a constant, the two are said to be directly proportional. x and y are directly proportional if the ratio y/x is constant.
- If the product of the two variables is always equal to a constant, the two are said to be inversely proportional. x and y are inversely proportional if the product x/y is constant.
- If a linear function transforms 0, a and b into 0, c and d, and if the product a b c d is not zero, we say a and b are proportional to c and d. An equality of two ratios such as a/c = b/d, where no term is zero, is called a proportion." Wikipedia, Proportionality

See Also

**Figure 14.10 - Proportionate Tonal Relations dictate Contraction or Expansion**
**Figure 6.17 - Areas and Volumes - Relations and Proportions**
**Figure 6.19 - Sphere to Cube - Relations and Proportions**
**Law of Definite Proportions**
**law of multiple proportions**
**Locked Potentials and Subdivisions**
**Locked Potentials and the Square Law**
**Part 12 - Russells Locked Potentials**
**Plancks Constant**
**Proportion**
**Reciprocating Proportionality**
**Scale of Locked Potentials**
**Table 2 - Controlling Modes and Proportions**
**3.13 - Reciprocals and Proportions of Motions and Substance**
**6.8 - Proportionate and Relative Geometries**
**9.12 - Velocity of Sound and its Propagation Rate are Proportional**
**12.00 - Reciprocating Proportionality**
**13.15 - Principle of Proportion**