Here's the question you clicked on:
SheldonEinstein
Can we prove the second postulate of bohr's work?
\[\large{mvr = \frac{nh}{2\pi}}\]
mvr = angular momentum
what do you mean prove it?
Yea like it mathematically.
oh man, thats some heavy math, i don't think i'm that good in it, try the math forum? and as far as i know it's not derived, it's postulated so i don't even know if you can prove it
No problem, well yes ! it's postulate so it can't be proved ... I hope scientists will find any way to prove it...
Like he said, it's a postulate. It can't be proven. I assume you're talking about the quantization of the angular momentum of the hydrogen atom.... this is a particular application of the general principle of Bohr-Sommerfeld quantization, in which classical physics is modified by requiring that integrals of the momenta over closed trajectories in phase space be equal to some integer multiple of planck's constant, or \[\int p_i dq_i = nh \] This technique was one of the first attempts at a workable quantum theory, and has long since been replaced by the full machinery of quantum mechanics. But, in many problems, it is an easy semi-classical approximation to the answer.
While not necessarily a proof, the 1927 De Broglie explanation sheds more light on its validity.