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!

Homework Help: Voltage difference, line integral

  1. Feb 21, 2013 #1
    1. The problem statement, all variables and given/known data

    I don't understand the follow formula of the integral :

    Integral of ( E dot dL) from B to A

    What direction is the dr vector? Is it the direction of the line integral?

    Say I want to derive the formula for electric potential due to a point in Space. E has a direction vector of ar
    assume dL is pointing from infinity to A (-ar), which is opposite of the Eletric Field. And the formula ends up with a negative sign, which is not consistent with the formal formula.
    Last edited: Feb 21, 2013
  2. jcsd
  3. Feb 21, 2013 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    The integral is you described, "Integral of ( E dot dL) from B to A", is $$\int_B^A \vec{E}\cdot\vec{dL}$$... that what you meant?

    dr points wherever you define it to point.

    The integral is along a line, which, in general, will curve in most coordinate systems.
    But does the potential difference in an electric field depend on the path taken? What does the rest of the theory say?

    I think you may have misplaced a minus sign.
    Last edited: Feb 21, 2013
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook