quantum

quantum

 [kwon´tum] (L.)

an elemental unit of energy; the amount emitted or absorbed at each step when energy is emitted or absorbed by atoms or molecules.

quan·tum

, pl.

quan·ta

(kwahn'tŭm, -tă),

1. A unit of radiant energy (Q) varying according to the frequency (ν) of the radiation.

2. A certain definite amount.

[L. how much]

quan·tum

, pl. quanta (kwahn'tŭm, -tǎ)

1. A unit of radiant energy (ε) varying according to the frequency (ν) of the radiation.

2. A certain definite amount.

[L. how much]

quantum

1. a quantity or amount.
2. the minimum quantity in which a neurotransmitter is secreted.
3. a unit of light.

photon 

The basic unit of radiant energy defined by the equation

E = hν

where h is Planck's constant (6.62 ✕ 10⁻³⁴ joule ✕ second), ν the frequency of the light and E the energy difference carried away by the emission of a single photon of light. The term photon usually refers to visible light whereas the term quantum refers to other electromagnetic radiations. See quantum theory; wave theory; troland.

quan·tum

, pl. quanta (kwahn'tŭm, -tǎ)

Unit of radiant energy (Q) varying by frequency (ν) of radiation.

[L. how much]