1. Not finding help here? Sign up for a free 30min 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!

Needle suspended from string - dipole moment?

  1. Sep 23, 2008 #1
    1. The problem statement, all variables and given/known data

    A needle suspended from a string hangs horizontally. The electrical field at the needle's location is horizontal with magnitude 3.7 x 10^3 N/C
    and it's at an angle of 30 degrees with the needle. There is no net electrical force acting on the needle, but the string exerts a torque of 3.7 x 10^-4 Nm to hold the needle in equilibrium. What is the needle dipole moment???

    2. Relevant equations

    t = torque
    p = dipole moment
    E = electric field

    t = p x E

    3. The attempt at a solution

    The way I am trying to solve this seems very easy and I thought I better check before turning this in.

    we want the dipole moment which is p, therefore

    p = t / E -->> p = 3.7 x 10^-4 / 3.7 x 10^3

    but then I'm thinking, the angle given in the problem statement come in play somewhere right???
    Am I in the right track???
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you help with the solution or looking for help too?
Draft saved Draft deleted

Similar Discussions: Needle suspended from string - dipole moment?
  1. Mass moments (Replies: 0)

  2. Moment of Inertia (Replies: 0)

  3. Resultant and Moment (Replies: 0)

  4. Moments and torque (Replies: 0)

  5. Moments of Inertia (Replies: 0)