# Spin angular momentum of a spin-1 particle

1. Feb 10, 2014

### liometopum

The spin angular momentum of a spin 1/2 particle is given by S = √(s(s+1))ℏ. If s =1/2,
S= ((√3)/2)ℏ

So, if s=1 is S= √2ℏ ?

2. Feb 10, 2014

### Staff: Mentor

Do you have some reason to be skeptical of the arithmetic?

3. Feb 11, 2014

### liometopum

Not at all. Every source I checked to confirm it only gave S for spin-1/2. Thanks!

4. Feb 11, 2014

### Staff: Mentor

It's a general relationship that applies to all kinds of angular momentum in QM.

Spin angular momentum: $S = \sqrt{s(s+1)} \hbar$

Orbital angular momentum: $L = \sqrt{l(l+1)} \hbar$

Total (spin + orbital) angular momentum: $J = \sqrt{j(j+1)} \hbar$

5. Feb 11, 2014

### liometopum

Thanks so much for helping clarify this!