Dictionary.com

Planck's constant

or Planck constant

Save This Word!

noun Physics.

the fundamental constant of quantum mechanics, expressing the ratio of the energy of one quantum of radiation to the frequency of the radiation and approximately equal to 6.624 × 10−27 erg-seconds. Symbol: h

QUIZZES

QUIZ YOURSELF ON “ITS” VS. “IT’S”!

Apostrophes can be tricky; prove you know the difference between it’s and its in this crafty quiz!
Question 1 of 12
On the farm, the feed for chicks is significantly different from the roosters’; ______ not even comparable.

Origin of Planck's constant

First recorded in 1905–10; named after M. K. E. Planck
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

Medical definitions for Planck's constant

Planck's constant
[ plängks ]

n.

The constant of proportionality relating the energy of a photon to the frequency of that photon. Its value is approximately 6.626 X 10-34 joule-second.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for Planck's constant

Planck's constant
[ plängks ]

A physical constant that is used extensively in quantum mechanics and fixes the scale of quantization of many phenomena, such as the relation between the energy of a photon (a quantum of light) and its wavelength. Its value is approximately 6.626 X 10-34 joule-seconds (equivalent to units of angular momentum). Planck's constant is fundamental to phenomena as the quantization of angular momentum and is used in Heisenberg's Uncertainty Principle. See also Dirac's constant quantize.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for Planck's constant

Planck's constant

A universal constant, first discovered by Max Planck, that states the mathematical relationship between the frequency of an electromagnetic wave and the energy in that wave. Planck's discovery unifies the seemingly contradictory observations that energy sometimes acts like a wave and at other times acts as if it is made up of particles.

Knowing Planck's constant sets the scale of energy for events in which the atom and subatomic particles take part.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
What's This Word?