A measure of the amount of incident energy that is absorbed per unit distance or unit mass of a substance.

In radiography, or ultrasound, the difference between the energy that enters a body part and the energy that is not detected: "The differences that occur with attenuation coefficients are caused by the absorption and scattering of energy within the body tissues."

A measure of the extent to which the index of refraction changes with applied high electric fields; such as, several parts per ten thousand for applied fields of the order of twenty volts per centimeter.

Since the phase shift of a light wave is a function of the index or refraction of the medium in which it is propagating, the change in index can be used to phase modulate the light wave by shifting its phase at a particular point along the guide, by changing the propagation time to the point.

The percentage of water that will be absorbed by a completely dry mass of soil and be held in equilibrium if the soil comes in contact with a saturated atmosphere.

The constant of proportionality in a formula for hysteresis loss.

The number of ion pairs formed per unit distance along the track of an ion passing through matter.

The ratio of observed osmotic pressure to that calculated for a solution of ideal behavior.

Referring to a measure of the technical efficiency with which a wind turbine converts wind energy into electricity: A power coefficient calculation is obtained by the rotating turbine as a percentage of the total energy of the wind passing through the area of rotation.

It does not necessarily follow that the higher the coefficient the better because above a certain wind speed excess energy must be wasted to avoid undue stress on the system.

1. The ratio of the complex electric field strength or voltage of a reflected wave to that of the incident wave.
2. The ratio of the phasor representing the magnitude and phase of the electric field of the backward-traveling wave at a specified cross section of a waveguide to the phasor representing the forward-traveling wave at the same cross section.