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!

Excess electrons or protons on drop.

  1. Jan 15, 2008 #1
    1. The problem statement, all variables and given/known data

    A small drop of water is suspended motionless in air by a uniform electric field that is directed upward and has a magnitude of 8450 N/C. The mass of the water drop is 3.80 10-9 kg.

    (b) How many excess electrons or protons reside on the drop?






    2. Relevant equations



    3. The attempt at a solution

    i'm not sure what i'm doing wrong, but i get about 4.1071 x 10^-12 C

    and for the drops i get 2.754 x 10-31

    not sure why its wrong?

    i used this for formula, see image: http://img180.imageshack.us/img180/6734/80350082pv3.png
     
  2. jcsd
  3. Jan 16, 2008 #2

    Kurdt

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I'm not sure what you're asking here really. I presume the image is the answer to the question and you're wondering why yours is different. From the 2.754x10-31 it appears you've multiplied the charge on the drop by that on a proton.
     
  4. Jan 16, 2008 #3
    well the image has different values to be calculated, and the image was just another example to show what was going on,

    the problem i calculated was different, but it should still be calculated the same.

    and it should be: 2.75e+07 but not sure why???
     
  5. Jan 16, 2008 #4

    hage567

    User Avatar
    Homework Helper

    I'm getting slightly different numbers than you, but are you sure you're dividing by the electron charge and not multiplying? That's the only way I can see you getting an answer with that magnitude.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Excess electrons or protons on drop.
Loading...