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!

Electricity and Magnetism

  1. Mar 25, 2010 #1

    So say you have a small ball hanging vertically below a positively charged plate. When the ball is released from rest with the string at a small angle to the vertical, it swings in periodic pendulum motion. If the ball is now positively charged, does the period increase, decrease or stay the same? And why?

    - Well at first, when it's neutral, there would be a slight attraction between the ball and the charged plate. But when the ball becomes positive as well, there would be now a slight repulsion. So would it stay the same?
  2. jcsd
  3. Mar 25, 2010 #2
    Do you know the differential equation for a simple pendulum? You could derive a similar equation with the electric force included. The solution should have the same form, so the period should be fairly obvious
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook