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.

 

[kerimek]

Dear student,

Your approach to the problem is correct, but there are a few things to keep in mind.

First, the equation you have used is the formula for the force between two parallel conductors, where μ is the permeability of free space, I(1) and I(2) are the currents in the two conductors, l is the length of the conductor, and a is the distance between the two conductors. This means that the force you have calculated is the force between the two wires, not on a specific wire.

Second, the force between two parallel conductors is attractive, which means that the two currents are flowing in the same direction. If one of the currents is twice the other, then the greater current must be the one in the wire that experiences the force.

With these points in mind, you can use the equation to solve for the greater current. Substitute the known values into the equation and solve for I(1). Then, since I(1) is twice I(2), you can multiply the value of I(1) by 2 to find the greater current.

I hope this helps guide you in the right direction. Keep up the good work in your studies!

Best,