# Planck's constant

**Planck's constant** was first discovered by Max Planck in experiments that helped lead to the formation of quantum mechanics.^{[1]} He formed the Planck Hypothesis, stating that radiation could only come in discrete packets now called photons. Planck's constant is usually written as *h,* but it's often useful to divide Planck's constant by , and then it is written , which is called h-bar:

^{[2]}

The value of the Planck constant^{[3]} is:

The value^{[4]} of :

To learn more about Planck's constant please see hyperphysics.

## References

- ↑ Rod Nave Hyperphysics (2015, June 20).
*Plank hypothesis*. [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/mod2.html#c3 - ↑ Rod Nave Hyperphysics (2015, June 20).
*Plank constant*. [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/tables/funcon.html - ↑ NIST (2015, June 20).
*Plank constant*. [Online]. Available: http://physics.nist.gov/cgi-bin/cuu/Value?h%7Csearch_for=planck - ↑ NIST (2015, June 20).
*Plank constant over*. [Online]. Available: http://physics.nist.gov/cgi-bin/cuu/Value?hbar%7Csearch_for=h-bar