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!

Magnetic flux in Toroid?

  1. Jan 17, 2017 #1
    1. The problem statement, all variables and given/known data
    The general method to find the total magnetic flux through an object is found by:
    Φ =∫B*ds (dot product)
    what is the ds over which we take the integral on??
    what surface is it?, is it the surface over which the magnetic flux enters?

    2. Relevant equations
    Φ =∫B*ds (dot product)

    3. The attempt at a solution
    well the problem is that a magnetic field can extend so far right??
    but in a toroid we assume that almost B= 0 anywhere other than in between the inner and outer radius.
    Therefore the surface should be one in between the inner and outer radii of the toroid, in a toroid like the in the figure attached the magnetic field is µ0NI/2πr
    therefore the total flux Φ =∫(µ0NI/2πr)*ds
    In the book ds is defined as h*dr (in the direction of phi)
    why can't ds simply be h*(b-a) namely the height of the toroid multiplied by the outer radius - the inner radius
    why is the term dr necessary??
    furthermore what is ds usually in general?

    Thank you
     

    Attached Files:

  2. jcsd
  3. Jan 17, 2017 #2

    NascentOxygen

    User Avatar

    Staff: Mentor

    H is not constant, it varies with r. So each of the small B.dA terms that you need to sum are going to have different values depending on r, hence the need for integral calculus.
     
  4. Jan 17, 2017 #3
    Thank you sir, now I get it
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Magnetic flux in Toroid?
Loading...