Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Electric Field

  1. Feb 19, 2007 #1
    1. The problem statement, all variables and given/known data

    If the electric field at a point in space has a magnitude of 300 volts/meter, about how far apart are the equipotential surfaces that differ by 10 volts?

    well, i think that they are 30 meters apart. All I did was

    300 volts/meter/10 volts since that will cancel the volts out i believe and leaving me with 300 meter/10 which give 30 meters.

    I dont understand this question since my professor decided to skip this portion of the chapter and expect us to know it.

    Any help on understanding would be great.
  2. jcsd
  3. Feb 19, 2007 #2


    User Avatar

    Staff: Mentor

    I think your answer and your intuition are correct. They certainly are for parallel plate capacitors. And I think they probably apply here for this spherical situation as well.
  4. Feb 19, 2007 #3


    User Avatar
    Homework Helper

    I don't think your math is correct. Your answer is really saying 30/meter.
  5. Feb 19, 2007 #4
    Be careful with your units.

    EDIT: hage567 beat me to it.
  6. Feb 19, 2007 #5
    I just realize that. Now i have a problem on doing conversion with this. Can any of you guys give me some pointer on how to understand this since I quiet dont understand it.

    I know there is this formula E = Kq/r^2 but I am not sure if that is what i have to use to figure this out.

    I have also seek my lab TA for help on this and I still haven't even gotten a response and its been like 2 days.
    Last edited: Feb 19, 2007
  7. Feb 20, 2007 #6
    Okay, i got some help but can anyone double check this to see if its the correct way,

    10 volts/ 300vots/meter = .033 meter
  8. Feb 20, 2007 #7


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Yes, that is right (assuming a uniform E field...that assumption is needed to answer the question). It's clear that this is correct since if the potential changes by 300 volts over a distance of 1.00 meter, it must take only 1.00 meter/30 to get a change of 10 volts.
  9. Feb 20, 2007 #8
    Sweet, thanks for checking it.

    thanks to everyone who posted here.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook