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: Still confused about this one

  1. Feb 8, 2004 #1
    The electric field at a distance of 10 cm from an isolated point charge of 2 x 10^-9 C is:

    A)1.8 N/C
    B)180 N/C
    C)18 N/C
    D) 1800 N/C
    E)none of these

    This is the formula I used Q=rv/k

    so (2x10^-9 C)(9x10^9 Nm^2) / .1 m C^2

    I am getting 180 N m/C - I have an extra m in the equation, which would make it none of the about. Evidently I am doing something wrong.

    Thanks
    Nautica
     
  2. jcsd
  3. Feb 8, 2004 #2

    jamesrc

    User Avatar
    Science Advisor
    Gold Member

    [tex] E = \frac{kq}{r^2} [/tex]
     
  4. Feb 8, 2004 #3
    You want E, not V.

    For a point charge:

    E = kq/r^2
     
  5. Feb 8, 2004 #4
    1800 N/C, thanks, nautica
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook