An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) Subdivision of an interval in a scale of measurement.
2) Geometry: Measure of angle, the 360th part of a circle.
3) Math.: Rank of an equation or expression as determined by the sum of the exponents of the variables.

From O.Fr. degré, from V.L. *degradus "a step," from L.L. degredare, from L. → de- "down" + gradus "step."

Darajé, from Ar. darajat "step, ladder."

The extent of → coherence of an → electromagnetic wave, as indicated by a → dimensionless number. Since interference takes place when waves are → coherent, using a → Young's experiment, the degree of coherence is measured from the → fringe  → visibility, V. It is defined as the ratio V = (I_max - I_min) / (I_max + I_min), where I_max is the intensity at a maximum of the → interference pattern, and I_min is the intensity at a minimum of the interference pattern. The electromagnetic wave is considered to be highly coherent when the degree of coherence is about 1, incoherent for nearly zero values, and partially coherent for values between 0 and 1.

→ degree; → coherence.

Of a → mechanical system, the number of → independent variables needed to describe its configuration.

→ degree; → freedom.

The number of electrons a neutral atom has lost in an ionizing physical process (radiation, shock, collision). In spectroscopy, the degree of ionization is indicated by a Roman numeral following the symbol for the element. A neutral atom is indicated by the Roman numeral I, a singly ionized atom, one which has lost one electron, is indicated by II, and so on. Thus O VI indicates an oxygen atom which has lost five electrons.

→ degree; → ionization.

The ratio of the intensity of polarized portion of light to the total intensity at a point in the beam.

→ degree; → polarization.

Statics: The → energy that must be expended to permanently disturb a specific state of → equilibrium of a body.

→ degree; → stability.

The → number of → edges incident on the → vertex.

→ degree; → vertex.

A equation in which the highest → exponent of the → variable is 1. Same as → linear equation.

→ first; → degree; → equation.

→ degree of polarization.

→ polarization; → degree.

A solid angle whose cone is a tetrahedral pyramid with an angle between its edges equal to 1°. 1 square degree = 3.046 x 10^-4 sr = 2.424 x 10^-5 solid angle of a complete sphere.

→ square; → degree.