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CGS & SI in electromagnetism

  1. Oct 5, 2015 #1
    Dear friends,

    As you know, in CGS units we have vacuum permeability as unity (1). so H=B and we use Oersted for H.
    on the other hand, in SI, permeability is (4 x pi x 0.0000001) and we use Ampere per meter for H. unfortunately after trying for couple hours, I couldn't derive the algebra of converting these to each other. everywhere they simply say just multiply 1000/(4 x pi) to amper per meter. but why? and how to derive this conversion coefficient?

    I know that cgs is cm gram second and si is meter kilogram second and i know how to convert these, but when amperes come into play and when the formulas are different in a coefficient, I just get confused.

    I apologies in advance if this looks ridiculous.
  2. jcsd
  3. Oct 10, 2015 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
  4. Oct 11, 2015 #3
    sorry, I dont have any modifications.
  5. Oct 11, 2015 #4


    Staff: Mentor

    Thread moved to General Physics, where more people might see it.
  6. Oct 11, 2015 #5


    Staff: Mentor

    You cannot derive it. It is just a definition. There is no deeper reason besides the fact that is how the SI units are defined.
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