# Momentum vs angular momentum

1. Jul 6, 2010

### AJ Bentley

I was just reading a text on QED that equates the vector potential to electrodynamic momentum using the de Broglie relationship.
At a later stage, the current flow in a conductor is predicted by considering the total momentum of the charge in relation to the electrodynamic.
Everything works out and it all fits.

But when I look at the dimensions, I find that the electrodynamic part has the units of angular momentum. Whereas the total momentum is of course, well, I assume it's momentum.

Is this valid? can I simply add angular and linear momentum and equate that total to wavenumber.

Or is it that the total momentum being considered in the text is in actual fact the total angular momentum? Presumably the author felt it too obvious to mention?

2. Jul 6, 2010

### Creator

How can anyone have a clue how to answer you correctly, AJ, if you haven't given the derivation OR the reference??

...

3. Jul 6, 2010

### Eynstone

Many texts refer to angular momentum simply as 'momentum'.

4. Jul 7, 2010

### AJ Bentley

Thank you, that's what I thought.
(The actual context of the question isn't important Creator - there's no point anyone delving into the text)

Last edited: Jul 7, 2010