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

Join the discussion
Registration is free. Start your own thread to ask a follow-up.
4 replies · 4K views
Hami Hashmi
Messages
40
Reaction score
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?
 
Physics news on Phys.org
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.
 
Hami Hashmi said:
I thought the formula for an electric field E=k*Q/d^2 (where k=constant, Q=source charge, and d=distance between the centers of the two objects)?
http://www.physicsclassroom.com/class/estatics/Lesson-4/Electric-Field-Intensity
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.
 
Hami Hashmi said:
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?
##\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##.