[PLAIN]http://img46.imageshack.us/img46/1699/dsfadsfas.png [Broken](adsbygoogle = window.adsbygoogle || []).push({});

The formula holds in the rest frame.

Why is this particular extension 'the' extension?

(Context is Electrodynamics/SR. It's just a piddly 16 lecture course that outlines Electrodynamics and SR and a bit of Quantum phenomena at the end. Ohm's law hasn't been mentioned and I don't think you're expected to know a lot about Ohm's law itself)

[edit]

Oh.

If you use a "taylor series in U" as in,

[tex]\sigma F^{ab}U_b = J^a + \lambda U^a[/tex]

and solve for lambda, it does turn out as what it's meant to be.

But why is this the correct thing to substitute in? Or is it a naughty question that demands us to be psychic?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Electrodynamics - relativistic generalization of a formula

**Physics Forums | Science Articles, Homework Help, Discussion**