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!

General charge question

  1. Feb 1, 2009 #1
    1. The problem statement, all variables and given/known data
    If I have a 24 volt power supply.The positive lead is attached to a disk and the negative lead is attached to another. The disks are separated by about 24 cm. The disks are on a sheet of carbon impregnated paper. Is the charge on the disk 24 volts?

    I am trying to determine the electric field strength at a point directly in the middle of the two disks.

    E= 2*8.99x10^9*q/r^2

    but I am not sure what the charge is on the sphere.
     
  2. jcsd
  3. Feb 1, 2009 #2

    Delphi51

    User Avatar
    Homework Helper

    You've got me confused, or at least the question has! Am I correct in picturing the two disks sitting flat on carbon paper with 24 cm between their outer edges?
    Under these circumstances, I don't think it is possible to determine the charges on the disks, if any. Where is the sphere?

    How could their be a single point in the middle of both disks?
     
  4. Feb 1, 2009 #3
    Thanks for responding.
    Sorry for the confusion.
    I am supposed to chart the electric field between two point charges.
    And determine the excess charge on each sphere.

    The carbon impregnated paper is used to model the electric field in a plane that passes through the center of two spheres. In this case, pennies.

    So basically, I attached the positive lead from the power source 24v to one disc and the negative lead to the other.

    I attached the negative lead of a voltmeter to the negative disc and used the positive to find the 4v,8v,12v,16v, and 20v equipotential lines on the paper. These locations I plotted on to a graph paper.

    I need to calculate the electric field strenght at a point b which is the intersection of a straight line that runs through the center of the discs and the 12 v equipotential line.

    I know the distance between the discs but I am not sure what the charges on the discs would be.
     
  5. Feb 1, 2009 #4

    Delphi51

    User Avatar
    Homework Helper

    Oh, interesting! You can actually measure the potential anywhere and find the lines. E field lines are perpendicula to equipotential lines. Neat.

    With all that information, you could use E = V/d to find the potential. Here "V" should be a delta V, the difference in potential between two points at the location you are interested in. Measure the potential difference and the distance between the two points - then you can calculate the Electric field strength.
     
  6. Feb 1, 2009 #5
    Thank you, I appreciate your response. It helped.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: General charge question
  1. General Question (Replies: 6)

  2. General questions (Replies: 2)

  3. General Questions (Replies: 1)

Loading...