Why is Planck's Constant important?
Even though it was first introduced in the Planck's law,
Where one quantum of radiation would have an energy,
Today almost all important relationships in quantum mechanics, contain Planck's constant (or the reduced Planck's constant
Examples would include,
1) de Broglie relation -
2) Schrodinger equation -
3) Commutator of
And so on.
It is to quantum mechanics, what the constants