Current - two parallel conductors

[hawkbyte]

Homework Statement

Two long parallel wires are separated by 4.0mm. The current in one of the wires is twice the other current. If the magnitude if the force on a 2.0m length of one of the wires is equal to 7.0μN, what is the greater of the two currents?

Homework Equations

F(b)=μ*I(1)*I(2)*l/2∏a

The Attempt at a Solution

I'm afraid I oversimplified my approach to this problem. I plugged the known values into the equation above and solved for I. I was then going to multiply that value by two. I am certain that is wrong, and that I am missing an important concept with regards to the problem. A shove in the right direction would be much appreciated!

 

[rock.freak667]

I think you are going correct. I just can't recall the formula for the force, so I will assume the one you posted is correct.