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Flux Density in Mutual Induction Solenoid with Core

  1. Jul 12, 2016 #1
    For a standard solenoid, I've found that
    B=μnI
    where
    μ = permeability of the core (4π×10^-7 for free space)
    n = number of coils
    I = current

    Firstly, is the permeability of soft iron 0.08, as I found?

    Primarily, however, I'm wanting to know if this still applies for a mutual induction apparatus like in
    https://www.scientrific.com.au/PDFs/em2220-001.pdf
     
  2. jcsd
  3. Jul 12, 2016 #2
    I think B=μnI/l where l is the length of the solenoid.
     
  4. Jul 22, 2016 #3
    Keep in mind that nothing interesting will happen with DC currents. Yes, a magnetic field will be generated but you will not get any mutual induction unless your flux is changing (i.e. varying current through one of the coils.
     
  5. Jul 25, 2016 #4
    It's for an alternating current.
    Presumably the maximum flux density will occur at the current peak?
     
  6. Jul 25, 2016 #5
    Yes, because
    f7c6a5d2ff27b8dae2e9aa5657aa5909a8bc6d8e (sorry, click on the link, I couldn't copy-paste the formula)
    and here B is a linear function of the current (I) as I wrote in my first post.
    hth
     
  7. Jul 25, 2016 #6
    Thanks, that's what I though :)
    Is the formula for the flux a solenoid correct though?
     
  8. Jul 25, 2016 #7
    You mean this: B=μnI/l ?
     
  9. Jul 25, 2016 #8
    It is correct assuming the solenoids length is much longer than the radius. B can be considered almost homogeneous inside the solenoid.
    But in any case B is linearly proportional to I.
    hth
     
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