1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    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!

How many excess electrons?

  1. Sep 1, 2013 #1
    The problem statement, all variables and given/known data

    A negatively charge balloon has 2.4 μC of charge. How many excess electrons are on this balloon? The elemental charge is 1.6e-19 C. Answer in units of electrons.

    The attempt at a solution

    I keep getting 1.5e13 electrons but the system is telling me it's wrong. I put it in many different forms and it still won't take it. (ex: 15000000000000)

    Is there something that I'm missing here?
  2. jcsd
  3. Sep 1, 2013 #2


    User Avatar
    2017 Award

    Staff: Mentor

    I can confirm your answer, and I don't know which format the website wants if 1.5e13 and 15000000000000 are not accepted.
  4. Sep 1, 2013 #3
    Thanks anyways. I hate these online homework systems.
  5. Sep 2, 2013 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    How about 1.5e+13?
  6. Sep 2, 2013 #5


    User Avatar

    Staff: Mentor

    The problem says "Answer in units of electrons." Could it be as simple as adding the word "electrons" to the result?
  7. Sep 2, 2013 #6
    I tried 1.5e13, 1.5e+13, 15000000000000, and 1.5e13 electrons. All of those answers register as the same. It says "You have already tried this answer". Gonna chalk this up as an error on their part. I'm sure my prof will get extra points.

    Thanks anyways guys...
  8. Sep 2, 2013 #7


    User Avatar
    2017 Award

    Staff: Mentor

    Well, at least the code to analyze answers is good :D.
    We all agree on the numerical value here, so the error is somewhere in the question or answer.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted