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!

Electric field due to dipole in polar coordinates

  1. Feb 22, 2015 #1
    For a dipole, if there is point subtending an angle ##\theta## at the centre of dipole and at a distance ##r## from centre of dipole, then the electric feild at that point can be broken into 2 components. One along the line joining the point and centre of dipole and point given by $$E_r=-\frac{\partial V}{\partial r}$$ and the other component along the perpendicular to that line as $$E_{\theta}=-\frac{1}{r}\frac{\partial V}{\partial \theta} $$
    This is given in my book. I understood E_r. But how did they get ##E_\theta## ?
    here ##V=\frac{pcos\theta}{4\pi\epsilon_0r^2}## ,r>>a.
     
  2. jcsd
  3. Feb 23, 2015 #2

    Orodruin

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    The electric field is minus the gradient of the potential. The equations you have written down are simply the expressions for the components of the gradient in spherical coordinates (apart from the ##\varphi## component that will be zero in this case).
     
  4. Feb 23, 2015 #3
    Why is there a 1/r term in E along theta? Is sphericcal coordinates beyaond my level?
     
  5. Feb 23, 2015 #4

    Orodruin

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    The components of the gradient essentially tell you how much something changes per length in that direction. If you change the radial coordinate by dr, you move a distance dr. Therefore, the radial component is ##-\partial V/\partial r##. If you change the coordinate ##\theta## by ##d\theta##, then you move a distance ##r\,d\theta## and the ##\theta## component is therefore ##-(1/r) \partial V/\partial\theta##.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Electric field due to dipole in polar coordinates
  1. Electric Dipole Field (Replies: 1)

Loading...