1. Limited time only! Sign up for a free 30min personal 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!

B If r=0 then will the electric charge of two points=infinity?

  1. Dec 26, 2017 #1
    I found that the electric field at r=0 equals infinity. What if two negative charges were put infinitely close together so the electric field was infinite, then would the charge of those two points be -infinity as well?
     
  2. jcsd
  3. Dec 26, 2017 #2

    Nugatory

    User Avatar

    Staff: Mentor

    The infinity that you found is telling you that the ##F=Cq_1q_2/r^2## formula doesn't apply and shouldn't be used when ##r=0##. It works anywhere outside of a charged sphere (a very large number of interesting and problems, which is why we use it), but ##r## is never zero if you are outside the charged sphere.
     
  4. Dec 26, 2017 #3
  5. Dec 26, 2017 #4

    Nugatory

    User Avatar

    Staff: Mentor

    That is the equation for the field. I gave the equation for the force, which is the product of the field and the charge the field is acting on. So replace the ##C## in my formula with ##k## - it's Coulomb's constant either way - and identify ##Q_1## as the source charge and the two equations are saying the same thing.
     
  6. Dec 27, 2017 #5

    PeroK

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    ##\frac10 \ne +\infty##

    ##\frac10## is undefined.

    What you can say is that:

    As ##r \rightarrow 0, \ \frac1r \rightarrow +\infty##

    What this means that as ##r## gets smaller, ##1/r## increases without bound. But, at no time do you arithmetically arrive at ##+\infty##.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Loading...