Homework Help: Magnetic field from four wires

1. Oct 8, 2012

Niles

1. The problem statement, all variables and given/known data
Hi

I am looking at four parallel wires of finite length L, whose currents run in the directions shown in the attached figure. There is no gradient along the wire-axis, so from Maxwell's equation
$$\frac{dB_x}{dx} = -\frac{dB_y}{dy} \equiv \tilde B.$$
How would I go about finding an expression for the gradient $\tilde B$ given some current I though the wires? This isn't a homework question, I have just not been able to find the answer anywhere.

Best,
Niles.

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Last edited: Oct 8, 2012
2. Oct 8, 2012

Staff: Mentor

I'm not seeing the figure...?

3. Oct 8, 2012

Niles

Sorry, I'll upload it in just a few minutes. Thanks for letting me know.

EDIT: I have attached it now. Thanks.