# Definition:Planck's Constant

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## Definition

**Planck's constant** is the physical constant $h$ which defines the quantum nature of energy and relates the energy of a photon to its frequency.

Thus:

- $E = \dfrac h f$

where:

- $E$ denotes the energy of a photon
- $f$ denotes the frequency of that photon
- $h$ denotes
**Planck's constant**.

It is used for describing the behaviour of particles and waves at an atomic scale.

**Planck's constant** also occurs in Heisenberg's uncertainty principle.

This article is complete as far as it goes, but it could do with expansion.In particular: Define what it is in terms of the physical constants which give rise to it, or to which it gives rise. Explain that its value is what it is because it is one of the fundamental constants of the universe which is used as one of the reference points used to define SIYou can help $\mathsf{Pr} \infty \mathsf{fWiki}$ by adding this information.To discuss this page in more detail, feel free to use the talk page.When this work has been completed, you may remove this instance of `{{Expand}}` from the code.If you would welcome a second opinion as to whether your work is correct, add a call to `{{Proofread}}` the page. |

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Physical quantities with the same dimension include angular momentum and action.

### Value

\(\ds h\) | \(=\) | \(\ds 6 \cdotp 62607 \, 015 \times 10^{-34}\) | joule seconds | \(\quad\) This sequence is A003676 in the On-Line Encyclopedia of Integer Sequences (N. J. A. Sloane (Ed.), 2008). | ||||||||||

\(\ds \) | \(=\) | \(\ds 6 \cdotp 62607 \, 015 \times 10^{-27}\) | erg seconds |

### Symbol

- $h$

The symbol for **Planck's constant** is $h$.

The $\LaTeX$ code for \(h\) is `h`

.

### Dimension

**Planck's constant** has the dimension $\mathsf {M L^2 T^{-1} }$.

### Units

The SI unit for **Planck's constant** is given as joule seconds:

- $\mathrm {J \, s}$

## Also known as

**Planck's constant** is also seen referred to as **the Planck constant**.

## Also see

## Source of Name

This entry was named for Max Karl Ernst Ludwig Planck.

## Sources

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