# Cross product Question

1. Aug 1, 2006

### gjfelix2006

Hi, my question is the following:

$\frac{\delta\vec E}{\delta t}\times \vec B = ?$
In other words, how can i develop this cross product.
Are there any identity that reduces this product?
Thanks.

2. Aug 1, 2006

### Staff: Mentor

Do you have E as a function of time? What coordinate system are you taking the cross product in?

3. Aug 1, 2006

### gjfelix2006

of course E is a function of time, and i think for simplicity the coordinate system is cartesian. Thanks

4. Aug 1, 2006

### StatusX

There is the product rule d/dt(E x B) = dE/dt x B + E x dB/dt. That's about all I can tell you unless you give us what E and B are explicitly (which is what I think berkeman was asking).

5. Aug 1, 2006

### Staff: Mentor

Fair enough. Take the derivative and use the determinant form of the cross product. That should get you what you need.

http://en.wikipedia.org/wiki/Cross_product