1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Magnetic flux, current and magnetic field confusion

  1. Apr 25, 2017 #1
    1. The problem statement

    Relevant equations: I am confused. When dealing with Ampères law:
    dl is supposed to be the length element? Like when we have Gauss' law for electric fields and we use a circular Gaussian surface, we have E(4πr^2)=Qenclosed/ε
    So in this case, when we have a circular loop our dl will be 2πr, since that is the circumference of the loop ? Or do I just understand nothing of this type of problem?
    I am confused because we seem to use 2π no matter what, like in this problem:

    3. The attempt at the solution:
    I don't see anyway to include 2π, but they still do:

    Attached Files:

    Last edited: Apr 25, 2017
  2. jcsd
  3. Apr 25, 2017 #2


    User Avatar
    Homework Helper
    Gold Member

  4. Apr 25, 2017 #3
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted