# Homework Help: Parallell magnetic wires

1. Jul 7, 2008

### K3nt70

1. The problem statement, all variables and given/known data
Consider two parallel conducting wires along the direction of the z axis as shown below. Wire 1 crosses the x-axis at x = -1.80 cm and carries a current of 2.60 A out of the xy-plane of the page. Wire 2 (right) crosses the x axis at x = 1.80 cm and carries a current of 8.80 A into the xy plane.
At which value of x is the magnetic field zero? (Hint: Careful with sign)
http://img234.imageshack.us/img234/6758/14937203wx9.png [Broken]
2. Relevant equations

$$B = \frac{ \mu I}{2 \pi r}$$

3. The attempt at a solution

Since i know that the point im looking for will be to the left of -1.80 cm on the x-axis, i should be able to deduce a distance from that point using:

$$\frac{2.6}{d} = \frac{8.8}{d + 3.6}$$

I found d to be 4.2871. I added this to 1.8 meaning the point it at -6.09 cm on the x axis, which is incorrect. Is my math wrong?

Last edited by a moderator: May 3, 2017
2. Jul 7, 2008

### K3nt70

edit: actially, i found d to be 1.50967 and the point on the x axis to be -3.3096 cm. This makes sense, but im kind of afraid to try it since i only have one more attempt at the problem. Any confirmations?

3. Jul 7, 2008

### K3nt70

nevermind. I checked my answers with the formual for magnetic field, and it was correct.