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!

Homework Help: Equipotential surfaces electric field problem

  1. Jan 27, 2010 #1
    1. The problem statement, all variables and given/known data
    A given system has the equipotential surfaces shown in the figure
    What is the magnitude of the electric field?
    What is the direction of the electric field? (degrees from + x axis
    What is the shortest distance one can move to undergo a change in potential of 5.00

    2. Relevant equations
    E= V/d



    3. The attempt at a solution
    I seem to be getting the same answer and its wrong I used the pythagoreon therom to find distances of each and divided the volts by the respecitive distances. I do not know what I am doing wrong I keep getting 2.24*10^2 V/m. Moreover, when I do the angle part I just do some trig and use that. Either way I try to do it and get 26.6 or 63.2. What am I doing wrong? Is the first part just the slope
     
  2. jcsd
  3. Jan 27, 2010 #2

    rl.bhat

    User Avatar
    Homework Helper

    Where is the figure?
     
  4. Jan 27, 2010 #3
    I can't see the figure yet either, but unless you're dealing with a uniform electric field then you can't use the equation you listed. As you said, electric field is the slope of a potential vs. position graph. If you're using calculus, it's the derivative with respect to position.
     
  5. Jan 27, 2010 #4
    I think I uploaded it now. Sorry!
    It is an attachment
     

    Attached Files:

  6. Jan 27, 2010 #5

    rl.bhat

    User Avatar
    Homework Helper

    Slope of the equipotential lines is tan(theta) = 2/4 = 1.2.
    Find theta.
    Distance between the equipotential lines d is x*sin(theta). Here x = 4 cm.
     
  7. Jan 28, 2010 #6
    SO part A is the slope = -1/2? But when I do tan^-1 (2/4) I still get 26.6. What am I doing wrong?
     
  8. Jan 28, 2010 #7

    vela

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    What is the relationship between the directions of the electric field and the equipotential lines?
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook