# Which of these does Planck's constant depend on?

Aug 18, 2017

Which what? Well, Planck's constant is... constant. So it should not depend on any variable. It is:

$h = 6.62607004 \times {10}^{- 34} \text{J"cdot"s}$

Common equations where you would see Planck's constant are:

• ${E}_{\text{photon}} = h \nu = \frac{h c}{\lambda}$, $\text{ }$ (Planck-Einstein Relation)

the energy of a single photon based on its frequency $\nu$. $c = 2.99792458 \times {10}^{8} \text{m/s}$ is the speed of light and $\lambda$ is its wavelength in $\text{m}$.

• $\lambda = \frac{h}{p} = \frac{h}{m v}$, $\text{ }$ (de Broglie Relation)

the wavelength of a particle with a mass $m$ and velocity $v$. $p = m v$ is its linear momentum.

• DeltaxDeltap >= ℏ/2, $\text{ }$ (Heisenberg Uncertainty Principle)

where ℏ = h//2pi is the reduced Planck's constant.