Force Between Parallel Conductors

[miniradman]

Hi there, I really need help with one question and help/hints would be greatly appreciated

1. A wire 3meters long, mass 0.10kg and carrying a current of 70.0 Amps floats without support above a horizontal wire 2.0cm below and parrallel to it. Find the current in the lower wire



2. I'm guessing this could be relevant formulas area? this formula

F/L = µo/2(pi) * I1 I2/d

where:
L= 3.00m
I1(subscript 1) = 70.00A
I2(subscript 2) = ?
d= 2cm or 0.02m



3. This is the exact working out that I have attempted

1/3 = (4(pi)*10^-7)/2(pi) * (70.0 I2/0.02)

= (8.79*10^-5)I2/0.125

*I am confused about the weight

 

[omoplata]

Apply Newton's 2nd law to the floating wire. Then you can find F. Then all you have to do is solve for I2.

 

[miniradman]

Oh thanks mate, that was a lot of help!

(I feel dumb now)

Cheers!

 

[omoplata]

No problem.

I had trouble with those problems once too.