1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Magnetic field at the centre of a cable that has an offset hole

  1. Nov 16, 2011 #1
    1. The problem statement, all variables and given/known data
    [From Electromagetism by I. S. Grant & W. R. Phillips, Q4.7]

    A cable of circular cross-section & diameter 0.2 m has a long cylindrical hole with a diameter of 0.001 m drilled in it parallel to the cable axis. The distance between the axis of the hole and cable axis is 0.005 m. The cable has a uniform steady current density of 10[itex]^{5}[/itex]A/m[itex]^{2}[/itex] flowing in it, determine the magnetic field at the centre of the cable.

    Answer: ∏ x 10[itex]^{-6}[/itex] Tesla

    2. Relevant equations

    Ampere's Law

    3. The attempt at a solution

    I know that to find the magnetic field I need to calculate the magnetic field of the cylinder carrying the current density and then add to the field of a current density -J in the opposite direction that would be occupying the hole. I've come up with the equation:

    B = μ/2 * J * (r[itex]_{1}[/itex] - r[itex]_{2}[/itex]) where r[itex]_{1}[/itex] is the distance from the axis of the main cylinder to the centre of it and r[itex]_{2}[/itex] is the distance from the axis of the hole to the centre of the main cylinder. However this gives me an answer of ∏ x 10[itex]^{-4}[/itex] T when I use r[itex]_{1}[/itex] = 0.01 m and r[itex]_{2}[/itex] = 0.005 m.

    What am I doing wrong? Any help is appreciated.
     
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted



Similar Discussions: Magnetic field at the centre of a cable that has an offset hole
  1. Coaxial cable, E-field (Replies: 0)

  2. Magnetic Fields (Replies: 0)

Loading...