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!

Electrostatics question

  1. Jul 30, 2016 #1
    1. The problem statement, all variables and given/known data
    Four point charges are placed at the corners of a square of side 1m as shown in Fig 18.54 Find
    a) the electric field, and
    b) the electric potential at the center of the square

    Photo is attached
    2. Relevant equations
    coulomb's law
    Ans of a=76.3 x 10^3 NC^-1 upward
    Ans of b=-25.4x 10^3 V
    3. The attempt at a solution
    I can do part a by 2x(2/10^6)x2x8.99x10^9xsin45 + 2x(2/10^6)x8.99x10^9xsin45=76.3 x 10^3 NC^-1 upward.
    I just attempted b part by 2x(2/10^6)xroot2x8.99x10^9xsin45 + 2x(1/10^6)xroot2x8.99x10^9xsin45
    because V=ED I just multiply each term by its length 1/root2 from the center.
    But the answer seems to be one third of the answer from part a, please teach me how to do.
     

    Attached Files:

  2. jcsd
  3. Jul 30, 2016 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Try doing it from the definition of the electric potential.
     
  4. Jul 30, 2016 #3
    Use the definition: work done per charge from infinity to the center?
     
  5. Jul 30, 2016 #4

    cnh1995

    User Avatar
    Homework Helper

    That will work. Potential at a point at a distance r due to a charge q is kq/r. You can add and subtract potentials aglebraically.
     
  6. Jul 30, 2016 #5
    Thanks I forget that voltage is scalar
     
  7. Jul 30, 2016 #6

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Well done.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Electrostatics question
  1. ElectroStatic Question (Replies: 5)

Loading...