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Homework Help: Easy dipole question help

  1. Oct 26, 2012 #1
    1. The problem statement, all variables and given/known data
    Cosnider two dipoles, p1 oriented along z at the origin, and p2 oriented along x at a distance r in the
    x - y plane. Given that the torque on a dipole in a field E can be written N = p x E, find the torque on each dipole about its centre.

    2. Relevant equations
    N=pxE , E= (p/4ε∏r^3)[2cosθrhat +sinθhat]

    3. The attempt at a solution

    for p1, I thought , since its on the origin , θ=0 , E=(p/2ε∏r^3)rhat

    first of all how do I know which direction is rhat in the x-y-z plane is it just in the z direction? , Now to find
    torque = px(p/2ε∏r^3)rhat

    and since is the centre of dipole r=r/2

    what do you guys think ?
    Cheers guys
  2. jcsd
  3. Oct 27, 2012 #2


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    Staff Emeritus
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    If you are referring the torque on p1 due to p2, then [itex]\hat{r}\ [/itex] is [itex]\hat{x}\ .[/itex]
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