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Why Is 'B' Used For Referring To A Magnetic Field?

  1. Mar 8, 2013 #1
    Why is the letter 'B' used for referring to a magnetic field? I've been searching high and low for the origins of this!

    Naturally, using 'E' to refer to an electric field makes sense, but does anyone know why 'B' was chosen for the magnetic field?
  2. jcsd
  3. Mar 8, 2013 #2


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  4. Mar 8, 2013 #3


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    No reason. But why use I for current, Q for energy, L for inductance? Which language the term was first used in could possibly be relevant. Dunno. I shouldn't worry about it. You are unlikely to forget it after having written your post. :smile:
  5. Mar 8, 2013 #4
    Thank you for the responses,
    I was just generally curious in the possible reasons as to why this letter was chosen, but you are right sophiecentaur, there are so many out there that don't really seem immediately. Many do seem to have some explanation behind them though, but couldn't really find anything related to the choice of B for magnetic fields!

    PhysicoRaj, your link makes for an interesting read, thank you :)
  6. Mar 9, 2013 #5
    There's a reason for all of those, I is for 'intensity', L is because of Lenz' law, Q for energy I've not seen much but it's probably the same as for Q for heat as 'quantity' and B was because of the order Maxwell was using for his quantities (A for potential and stuff). It is of course entirely arbitrary but most of them do have a reason behind them, just an arbitrary one.
  7. Mar 9, 2013 #6


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    FWIW, the same explanation applies to some of the standard notation in solid mechanics, for example D for the "compliance matrix" relatiing stresses and strains, and B for the strain - displacement relationship in finite element formulations. One of the key early papers just named matrices in alphabetical order, and the B and D matrices turned out to be more generally useful than A and C - though it would be more logical to call the compliance matrix C mot D!

    Some of these notations are language-dependant. For example I've seen French mech engineers write Z for "mass" instead of M.

    And Laplace used "c" for the base of natural logs, not the modern "e".
  8. Mar 9, 2013 #7
    You could just refer to it as the "Bagnetic field" if the difference in letters bothers you. ;)
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