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

  1. Nov 3, 2009 #1
    1. The problem statement, all variables and given/known data

    a long straight 6mm diameter conducting wire is carrying a current of 4A.

    1)What is the magnitude of the magnetic field at a point 1mm inside the surface of the wire.

    2)what is the magnitude of the magnetic field at a point 2cm from the centre of the wire


    2. Relevant equations

    using amperes law:
    for part 1 i got 44*10^-9

    and for part 2: 50*10^-9

    I wnt to make sure i have done it right though, becuase it is a past exam question that i dont have solutions for. So if anyone is good at these questions, it would be helpful to check my answers in case i have stuffed up.


    3. The attempt at a solution
     
  2. jcsd
  3. Nov 3, 2009 #2

    kuruman

    User Avatar
    Homework Helper
    Gold Member

    The answers to both parts are incorrect.
     
  4. Nov 3, 2009 #3
    how do you calculate current inside the wire? And do you notice units of all parameters when you calculate?
     
  5. Nov 3, 2009 #4
    what i tried was:

    diameter =6mm. At a point 1mm inside the conducting wire, diameter is 4mm, therefore r=2mm

    using amperes law:

    ∫B⋅ds=μ₀I{Through}

    ds=2πr
    I{Through}=I∗((πr²)/(πR²)) where R=6mm and r =2mm
    B*2πr=I∗((πr²)/(πR²))

    B=μ₀Ir/2πR²
    B=μ₀(4)(0.002)/2π(0.006)²
     
  6. Nov 3, 2009 #5
    You wrote diameter = 6mm but then when you put it into eq, you wrote R=6mm.
     
    Last edited: Nov 4, 2009
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Magnetic field
  1. Magnetic Field (Replies: 0)

Loading...