Question

A vertical straight wire carrying an upward 28 -A current exerts an attractive force per unit length of 6.7*10^-4 N/m on a second parallel wire 6.0 cm away.

A.)What current (magnitude) flows in the second wire?

B.What current (direction) flows in the second wire? Upward or Downward.

Answer 1

I am going to answer part B first. Since the force between the two wires is attractive, that automatically tells us that the currents are flowing in the same direction. Since the current in the first wire travels upward, then so does the current in the second.

Now to find the value,

The formual to use is

F/l = μ_oI₁I₂/2πr

6.7 X 10^-4 = (4π X 10^-7)(28)(I₂)/(2π)(.06)

I₂ = 7.18 A