Parallel Wires: Force per Unit Length Calculation

[Kris1120]

Homework Statement

Two parallel wires are 6.8 cm apart, and
each carries a current of 23.8 A.
The permeability of free space is 4pi ×
10−7 T · m/A.
If the currents are in the same direction,
find the force per unit length exerted by one
of the wires on the other.
Answer in units of N/m.

Homework Equations

F/L = (permeability)/(2*pi*d) * 2I

The Attempt at a Solution

F/L = (4*pi*10^-7 T*m/A)/(2*pi*0.068m) * 2(23.8 A)
= 0.00014 N/m

 

[alphysicist]

Hi Kris1120,

Homework Statement

Two parallel wires are 6.8 cm apart, and
each carries a current of 23.8 A.
The permeability of free space is 4pi ×
10−7 T · m/A.
If the currents are in the same direction,
find the force per unit length exerted by one
of the wires on the other.
Answer in units of N/m.

Homework Equations

F/L = (permeability)/(2*pi*d) * 2I

This equation is not correct. Do you see what it needs to be?

 

[Kris1120]

I^2 and not 2I!

 

[Kris1120]

Thanks!