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Why we use relative permeability

  1. Nov 3, 2017 #1
    Why we use relative permeability if we have absolute
    permeability in electromagnetism?
     
  2. jcsd
  3. Nov 3, 2017 #2

    BvU

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    Because it's easier ?
    Perhaps you want to show some examples where you think different ?
     
  4. Nov 5, 2017 #3
    I am more concerned regarding the theoretical aspect. Why cannot we just take absolute permeability of any material? In fact i have started reading about transformers and there i found relative permeability.
     
  5. Nov 5, 2017 #4

    BvU

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    Theoretical aspect ? Is ##\vec B = \mu \vec H## absolute enough ?
    who is 'we ' ?
    Who say we can not ?
    I can't guess where you found this. Oherwise I could try to explain... Please tell us where.
     
  6. Nov 6, 2017 #5

    vanhees71

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    Well, while permittivity and permeability of the vacuum, ##\epsilon_0## and ##\mu_0## are mere conversion constants from unnatural SI units to natural units, ##\epsilon_r## and ##\mu_r## are effective physical properties of the material, derivable from the microscopic structure of it in terms of linear-response theory.
     
  7. Nov 6, 2017 #6

    Charles Link

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    The relative permeability ## \mu_r ## gives the factor that the magnetic field in the core material is increased by over the applied magnetic field from the current in the conductor coils of a solenoid or transformer. The absolute permeability ## \mu=\mu_o \mu_r ## has an extra factor of ## \mu_o ## in it, (in SI units), which obscures this simple result. ## \\ ## In c.g.s. units, ## B=\mu H=\mu_r H ##, this problem is absent, because ## B=H+4 \pi M ##, without any ## \mu_o ## in front of the ## H ##.
     
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