1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Geometric transformation of E field to B ?

  1. Feb 1, 2016 #1
    When a test charge is stationary, it generates an E field with zero curl.

    When it moves, it generates a circulating magnetic field B...( as well as the E field.)

    Is there a geometric reason for this? How does motion alone generate a circulating field B?

    Can we call this change a 'transformation' even?
  2. jcsd
  3. Feb 1, 2016 #2
    By moving an electric field, you are changing the electric field. A changing electric field is essentially a magnetic field.

    Not sure how much calculus you know, but this is very well-understood. The relationship is described in Maxwell's equations.
  4. Feb 1, 2016 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    The fundamental reason is relativity. The textbook by Purcell, Electricity and Magnetism, is the classic presentation of this. For a similar presentation, see section 23.2 of my book Light and Matter: http://lightandmatter.com/lm/ .
  5. Feb 1, 2016 #4
    Thanks much, that's what I needed i.e. a text that deals with this. I'm working through Griffiths E&M right now and I don't think he deals with it.
  6. Feb 1, 2016 #5


    User Avatar
    Science Advisor
    Gold Member

    According to numerous posts on PF, Griffiths does cover this topic in a manner similar to Purcell.
  7. Feb 1, 2016 #6
    It's not in chapter 5, maybe chapter 12 which introduces relativity.
  8. Feb 6, 2016 #7
    p.s. By the way, it is in Griffiths chapter 12, pretty much the last section of the last chapter, has a section on the transformation from E to B. However, I think bcrowell was referring to purcell because that would deal with it in more depth.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook