Understanding the Difference Between B and E Fields

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Discussion Overview

The discussion revolves around the terminology and conceptual differences between the magnetic field (B) and electric field (E), particularly focusing on why B is referred to as magnetic induction rather than magnetic field strength. Participants explore the implications of these terms in various contexts, including material properties and theoretical frameworks.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants question why B is not called magnetic field strength like E, suggesting that "magnetic induction" is less descriptive.
  • Others explain that the terminology stems from historical decisions made during international conferences, highlighting a split between physicists and engineers regarding the naming of physical quantities.
  • It is noted that B is referred to as magnetic flux density in units of Weber per square meter, which some find unwieldy.
  • One participant argues that B is not a good descriptor of magnetic field strength when considering material properties, suggesting that H is a better descriptor.
  • Another participant clarifies the relationship between E, H, B, and D, indicating that E and H are counterparts, while B is the counterpart of D (electric flux density).
  • There is a mention that B and H may appear similar macroscopically, but they differ significantly on a smaller scale, similar to the relationship between E and D.
  • It is proposed that B depends on the medium, whereas H does not, adding another layer to the discussion of their differences.

Areas of Agreement / Disagreement

Participants express differing views on the appropriateness of the terms used for B and E, with no consensus reached on the best terminology or conceptual framework. The discussion remains unresolved regarding the implications of these terms in various contexts.

Contextual Notes

Participants reference historical context and definitions that may not be universally accepted, indicating that the discussion is influenced by varying interpretations of physical quantities and their relationships.

manjuvenamma
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Why don't we call B magnetic field strength like we call E, the electrical counterpart. In stead we call it magnetic induction which is less descriptive.
 
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That is due to the intenational conferences the "named" physical quantities and invented SI. Unfortunately, there was a split in the '50s between physicists and (mostly industrial) engineers. The engineers were most interested in magnetic flux, which powered their generators. They invented the Weber of flux and called B "magnetic flux density" in units of Weber per square meter. That name was unwieldy, even for them, so someone suggested the strange term "magnetic induction". The engineers were careful not to give B the same name as E, so as not to confuse the two. Physicists know it is no confusion, after Maxwell and Einstein, that E and B are just different components of the same tensor. Several advancedl EM texts call B the magnetic field as you and I suggest.
These books also use the same unit, gauss, for B and E, in gaussian units.
 
The problem is that, as soon as you look at material properties, B is not a good descriptor of magnetic field strength, which is better described by H.
 
manjuvenamma said:
Why don't we call B magnetic field strength like we call E, the electrical counterpart. In stead we call it magnetic induction which is less descriptive.

I'm not sure what you mean by "counterpart"? "E" has units of volts/meter, and is the electric field intensity. "H" has units of amps/meter and is called magnetic field intensity. It appears that E and H are "counterparts". Also, at a boundary of 2 different materials, the "normal" (perpendicular) components of "B" in both materials, and that of "D" in both are equal. But, the tangential components of "E" are equal for both materials, as well as that of "H".

It is obvious that "B" is the counterpart of "D", the electric flux density, aka "electric displacement", whereas "H" is the counterpart of "E".

I hope this helps. BR.
 
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see B is magnetic induction which gives effect of magnetic field H .they both look like same macroscopicaly but on a smaller scale there is a huge diff. b/w them just like there is b/w E and D.
B will also depend on the medium while H does not.
 

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