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!

Make sure electro does not fall!

  1. Jun 18, 2010 #1
    THIS IS NOT A HOME WORK QUESTION THIS AS FROM ANOTHER Tutorial

    find the electric field E need to prevent an electron from falling down to ground, when close to surface of the earth.

    i approached this question saying that take gravity into account and take earth to be negatively charged.

    then Fg=Eq then Fg/q=E..........

    mg/q=E

    is this correct?

    if not can you explain the reasoning plz!
     
  2. jcsd
  3. Jun 18, 2010 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Looks good to me.
     
  4. Jun 18, 2010 #3
    normally do we take earth to be + or negative?
     
  5. Jun 18, 2010 #4

    Doc Al

    User Avatar

    Staff: Mentor

    The electric field surrounding the earth points downward. (The earth is negatively charged.)
     
  6. Jun 18, 2010 #5
    thanks that makes more sense now!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook