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B Magnetic permeability...

  1. Sep 25, 2015 #1
    Who is credited for deriving the value of magnetic permeabilty in a classical vacuum?
    How would one go about sourcing information in relation to such a value?
  2. jcsd
  3. Sep 25, 2015 #2


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    μ0 = π * 4E-7. It's just a passed value, that is comfortable.

    Say you have a long straight conductor carrying a current = 1 Adc.

    In a distance, R = 1 m, you will find H = 1A / 2πR [ A/m ] = 1 / 2π [ A/m ].

    To find the B-value, you multiply by μ0, so

    B = 2E-7

    which some people regarded as a comfortable value ?

    Anyway the value π is not included in the value of B, and B "becomes close to" about 1T in practical applications ( a magnet you know where to buy ).

    It's just like 1 meter = a long step.
  4. Sep 26, 2015 #3
    when using this value in a research paper who would I give credit to?
  5. Sep 26, 2015 #4


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    Well, mayby the members at some congress have voted as for the factor 4*10-7.

    I think the factor π has just been accepted as ok. :smile:

    The idea has just been to achieve a practical unit ( Tesla ) with a value about 1. ( for a "normal" magnet ).
    Last edited: Sep 26, 2015
  6. Sep 26, 2015 #5
    µ0 = 4π×10−7 N / A2 ≈ 1.2566370614...×10−6 H / m or T·m / A or Wb / (A·m) or V·s / (A·m)

    So when using any of the above values in a peer review research paper, I would give reference to electromagnetic theory and electromagnatism?
  7. Sep 26, 2015 #6


    Staff: Mentor

  8. Sep 26, 2015 #7
  9. Sep 26, 2015 #8

    Vanadium 50

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    If you had taken the advice PF had given you, you would be reading journals, and you would have all the citation examples you could use.
  10. Sep 27, 2015 #9


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    Thread closed.
    Last edited by a moderator: Sep 27, 2015
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