# Electric and Magnetic field relationship

1. Oct 26, 2007

### Tareth

1. The problem statement, all variables and given/known data
Show that B = (k)v(cross)E

3. The attempt at a solution
I have no idea where to start. I have the F = qE and F = q(v(cross)B)

2. Oct 28, 2007

### Tareth

Just a starting point would be much help.

3. Oct 28, 2007

### learningphysics

did you post the question exactly?

Is the question asking to prove that in general:

$$B = k\vec{v}\times\vec{E}$$

I don't recognize this relationship... is this for a specific situation?

4. Oct 28, 2007

### Tareth

That is the first part of the problem.

Show that $$\vec{B} = k\vec{v}\times\vec{E}$$

Find the fundamental units of k, which I believe I have correct as $$m^2/s^2$$

Find $$\vec{B}$$(dot)$$\vec{E}$$

Find $$\vec{E}\times\vec{B}$$

I believe with the 1st part I can figure the rest out. I just don't know where to start to prove the first part.

5. Oct 28, 2007

### learningphysics

In general? Or for a specific situation?

6. Oct 28, 2007

In general.