# Homework Help: Differentiating electromagnetic field

1. Feb 5, 2004

### jlmac2001

For question 3, i don't know ho to differentiate the electromagnetic field. Can someone help me?

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2. Feb 5, 2004

### jlmac2001

correction

It's question 2

3. Feb 6, 2004

### HallsofIvy

If F(x,y,z,t) the "total derivative of F is:
$$\frac{\partial F}{\partial x}dx+\frac{\partial F}{\partial y}dy+\frac{\partial F}{\partial z}dz+\frac{\partial F}{\partial t}dt$$

4. Feb 6, 2004

### jlmac2001

help with #2 not #3

I put the wrong question number down. It's #2 that I need help with. Can someone help?

5. Feb 7, 2004

### HallsofIvy

Odd. Your second post telling us that it is "problem 2 not problem 3" appears after my post but with an earlier "time stamp".

In any case, I have already given the general formula for "total differential". You might also want to know that, for a vector valued function E, $$\frac{\partial(E.E)}{\partial x}= 2E.\frac{\partial E}{\partial x}$$. That should be all you need.

Last edited by a moderator: Feb 7, 2004