# Planck's constant

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Related to Planck's constant: Reduced planck's constant

## Planck's constant

(plängks), fundamental constant of the quantum theoryquantum theory,
modern physical theory concerned with the emission and absorption of energy by matter and with the motion of material particles; the quantum theory and the theory of relativity together form the theoretical basis of modern physics.
. It is represented by the letter h and has a value of 6.62607 × 10−34 joule-second. The combination h/2π, denoted by h (called "h-bar"), occurs frequently.

## Planck's constant

A fundamental physical constant which represents the elementary quantum of action, action being defined as energy multiplied by time. Introduced by Max Planck in 1900, it has the value h = 6.6261 × 10-27 erg-second or 6.6261 × 10-34 joule-second. The symbol &planck;, sometimes called the Dirac h, is often used for convenience in physics to denote the quantity h/2π, where π = 3.1416….

As used by Planck in deriving his radiation law, h multiplied by the frequency of radiation represented a bundle of energy, that is, a quantum of energy. Radiant energy at any wavelength can occur only as multiples of this energy; thus energy is quantized. See Compton effect, Fundamental constants, Heat radiation, Quantum mechanics

## Planck’s Constant

(the quantum of action), a fundamental physical constant that determines a broad range of physical phenomena characterized by discreteness of action. These phenomena are studied in quantum mechanics. Planck’s constant was introduced by M. Planck in 1900 in establishing the law of energy distribution in a blackbody radiation spectrum. The symbol for the constant is h.

The most accurate value for Planck’s constant has been obtained on the basis of the Josephson effect: h = (6.626176 ± 0.000036) × 10–34 joule-Hz–1 = (6.626176 ± 0.000036) × 10–27 erg-Hz–1. The constant = h/2π = (1.0545887 ± 0. 0000057) × 10–27 erg-Hz–1, which is more often used, is also called Planck’s constant.

## Planck's constant

[′pläŋks ‚kän·stənt]
(quantum mechanics)
A fundamental physical constant, the elementary quantum of action; the ratio of the energy of a photon to its frequency, it is equal to 6.62606876 ± 0.00000052 × 10-34 joule-second. Symbolized h. Also known as quantum of action.
References in periodicals archive ?
This new NIST measurement joins a group of other new Planck's constant measurements from around the world.
We have expressed Planck's constant in terms of the spacetime continuum constants [[bar.
The size of each allowed orbit is determined by the key numerical quantity of quantum physics, Planck's constant.
This insight served to entrench Planck's constant in physical reality to a degree unapproached up to that time.
It was shown that in the absence of a purely gravitational measurement of Planck's constant one cannot at present rule out the possibility that gravitational quanta may be scaled by the more diminutive of nature's two elementary "actions", namely, [e.
The Planck time is also calculated from the gravitational constant, the speed of light and Planck's constant in such a way that moving at one Planck length per one Planck time would be equal to the speed of light.
Quantum theory began in the early 1900s with the investigations by Max Planck, who determined that energy (light, radiation, heat) on the atomic level is emitted not in an infinitely divisible range of values but in discrete packets, called quanta (singular quantum), the value of which is called h or Planck's constant.
wherein v, c, h, k and T represent the frequency of interest, the speed of light, *1 Planck's constant, Boltzmann's constant, and absolute temperature, respectively.
8:00 DETERMINING PLANCK'S CONSTANT FROM THE PHOTOELECTRIC EFFECT USING LEDs AND LASERS AS LIGHT SOURCES, Max F.
Those are the size of the electron's charge, the speed of light, and Planck's constant, which defines the scales at which quantum phenomena operate.
In addition, Warner Heisenberg (a collaborator of Bohr) proposed his now-famous uncertainty principle, which stated that Planck's constant is used to define the ultimate limit of the accuracy of measurements of subatomic particles.

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