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 potential when there is a negative test charge?

  1. Mar 1, 2014 #1
    For when there is a negative test charge:

    The work done to get from infinity to r would be negative, corresponding to a decrease in potential energy so

    since dr must be a path element and therefore in the negative direction (towards the source of the E field)

    does that mean the direction of the force I apply would be towards infinity?
  2. jcsd
  3. Mar 1, 2014 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    I believe a negative charge experiences a force towards the direction of the source of the E-field.
  4. Mar 2, 2014 #3


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    A field doesn't really have a 'source', though. A static E field exists between two charges or between a charge and infinity. It is far better just to start with the definition of field and potential (which involves energy or force associated with a Unit Positive charge) and just go along with where the signs of the charges and directions of any vectors etc. If you try to have a different rule for what will happen for every combination of charge sign, etc., then you are making life hard for you and your memory. Physics tries to avoid that sort of problem.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Electric potential when there is a negative test charge?