B-field wires

[tandoorichicken]

Two parallel wires repel each other with a force per length of 1.00*10^-3 N/m when spaced a distance of 2.50 cm apart. If one wire has a current of 100A, what is the current in the other wire?

Don't know where to start this one.

[Chen]

Two equations. First, the magnetic field that a wire with current creates at a distance of r from it is:
B = \frac{\mu _0I}{2\pi r}
Second, the magnetic force that operates on a wire with current inside a magnetic field is: (When the magnetic field is perpendicular to the direction of the current)
F_m = IBl
To find the force per length, just divide it by l.

Now can you solve it? [:)]