Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

What is the most direct way of observation of quantization of angular momentum?

share|improve this question
    
Possible duplicates: physics.stackexchange.com/q/11197/2451 and links therein. –  Qmechanic Apr 14 '13 at 9:55

2 Answers 2

up vote 3 down vote accepted

Rotational spectroscopy seems like a pretty obvious demonstration of quantised angular momentum. If you look at the microwave absorption spectrum of a diatomic molecule (with a non-zero dipole moment) you'll find equally spaced absorption lines. These arise because the angular momentum can only change in integral jumps of $\hbar$.

share|improve this answer

The Stern-Gerlach experiment also demonstrates (quite fantastically) the quantization of angular momentum.

The full details are in the Wikipedia page linked, but the essential principle of the experiment is this -

They sent a beam of silver atoms through an inhomogeneous magnetic field. Silver atoms have one unpaired electron, so the net angular momentum of the atom will be the spin angular momentum of the electron.

Classically you expect that the spin of the electron can be oriented along any random direction, therefore you'll see a spread of particles when they hit the photographic plate. But what they actually observed was two distinct beams of silver atoms. This was interpreted to mean that the angular momentum of an electron can have only two values: $\hbar/2$ and $-\hbar/2$.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.