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!

Net force on charges found to be zero

  1. Sep 3, 2006 #1
    I'm having trouble understanding some of these basic electrostatic priciples and my book isn't much help. I've put them in a true/false format. If I could get at few answers, it would really help me understand this.

    A positive point charge +q is placed at point p to the right of two charges, A and B. The net force on the +q charge is found to be zero. Which of the statements below are true?

    A-----------B-----------P
    ++++++++++++++++++++q

    True or False -- The magnitude of the charge A must be smaller than B.

    True or False -- Reversing the sign of +q to -q would make the force on it nonzero.

    True or False -- B must have the same sign as A and be less in magnitude.

    True or False -- B must have the opposite sign from A and be less in magnitude.

    True or False -- Either A or B must be positive.
     
  2. jcsd
  3. Sep 3, 2006 #2
    Welcome to PF eltel.
    What are your thoughts on how to go about solving the questions ?
    Start from the basics, namely Coulomb's law .
     
  4. Sep 3, 2006 #3
    I eltel,
    you must analyse two cases:
    A negative then B must be positive so that the net force be zero on p.
    A positive then B must be negative....
    Then use Coulomb's law to complete your reasoning.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?