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: Work Done line Integral question - Electrostatics - help please

  1. May 4, 2015 #1


    Can anyone please tell me where I am going wrong? I am getting the incorrect answer for the Word Done should be: WD = q(3x^2-6y) ...

    Apologies for not changing it into the format on here - but for my revision I have pretty much done that myself.
    Last edited: May 4, 2015
  2. jcsd
  3. May 4, 2015 #2


    User Avatar
    Science Advisor
    Homework Helper
    2017 Award

    You showed that ##\vec E## as given is curl free. Well done.
    Then you worked out that ##\displaystyle q\int_{(0,0,0)}^{(x_1, y_1,0)} \vec E\cdot \vec{dl} = q\left(3x_1^2y_1 - y_1^3\right )## (small omission of the ##^2## ).

    To check it, you could verify that ##V = -\nabla\cdot E## is satisfied if ##-V(x,y,z) = 3x^2y - y^3## and then you can immediately see that W.D. is what you found (when you fix the missing square) and not q(3x2-6y).

    You could double check with another path: from (0,0,0) to (0, y1, 0) and then to ( x1, 0, 0) which givves the very same result.

    Have some faith and if we're both wrong don't hesitate to inform me with another post ! I love (:wink:) to be corrected when I'm wrong.

    (happens all the time :cry: )
  4. May 4, 2015 #3
    Thanks - I guess I was just doubting myself! Really appreciate you helping me out like that. Sam.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted