Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: B-field wires

  1. Mar 23, 2004 #1
    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.
  2. jcsd
  3. Mar 24, 2004 #2
    Two equations. First, the magnetic field that a wire with current creates at a distance of [tex]r[/tex] from it is:
    [tex]B = \frac{\mu _0I}{2\pi r}[/tex]
    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)
    [tex]F_m = IBl[/tex]
    To find the force per length, just divide it by [tex]l[/tex].

    Now can you solve it? :smile:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook