quantum (redirected from Quantum (physics))

quantum /quan·tum/ (kwon´tum) pl. quan´ta   [L.] a unit of measure under the quantum theory (q.v.).

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quan·tum (kwntm)

n. pl. quan·ta (-t)

1. The smallest amount of a physical quantity that can exist independently, especially a discrete quantity of electromagnetic radiation.

2. This amount of energy regarded as a unit.

3. A quantity or an amount.

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quantum (kwon´tm),

n a discrete unit of electromagnetic energy or of a roentgen. A quantity becomes quantized when its magnitude is restricted to a discrete set of values as opposed to a continuous set of values.

quantum theory,

n See theory, quantum.

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quantum

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

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quantum theory

radiation and absorption of energy occur in quantities (quanta) which vary in size with the frequency of the radiation.

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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.