• Support PF! Buy your school textbooks, materials and every day products via PF Here!

Electric field using Gauss' Law

1. Homework Statement
Two small insulating spheres with radius 9.00×10−2m are separated by a large center-to-center distance of 0.545 m . One sphere is negatively charged, with net charge -2.35 μC , and the other sphere is positively charged, with net charge 4.35 μC . The charge is uniformly distributed within the volume of each sphere.
What is the charge at the midway point between charged spheres
2. Homework Equations
Gauss' Law: I will use ∫ for closed surface integral
∫E⋅dA=Qenclosed/ε0

3. The Attempt at a Solution
I used two gaussian surfaces. One encapsulating the negatively charged sphere and one the positively charged sphere. The radius of my gaussian surface was half the distance between the spheres, 0.2725m.
In gauss' law E can come out of the integral and the integral of dA is A.
Area of sphere is 4πr2
E4π(0.2725m)2=(2.35x10-6C)/(8.85x10^-12C2/Nm2)
This E will be pointing away from the negatively charged sphere at the midpoint between two charged spheres.

I did this for the positively charged sphere as well using a gaussian surface with the same radius(as above). I obtained an Electric field that this sphere contributes at the midpoint. I summed them up and got a total electric field. This answer is incorrect.
Not sure what Im doing wrong,
The problem gives the radius of both charged spheres so maybe this comes into play somewhere?
Thanks a bunch!
 
Last edited:

Orodruin

Staff Emeritus
Science Advisor
Homework Helper
Insights Author
Gold Member
2018 Award
15,952
5,920
How do you imagine that we will be able to help you if you do not show us what you did? You need to both describe it in words and show us all your computations. Otherwise it is just not feasible to find where you go wrong.

Edit: You also failed to actually specify what the question asks you to do. You just described the setup.
 
How do you imagine that we will be able to help you if you do not show us what you did? You need to both describe it in words and show us all your computations. Otherwise it is just not feasible to find where you go wrong.

Edit: You also failed to actually specify what the question asks you to do. You just described the setup.
I didnt write out all my calculations because I was more asking if the method was correct. What I mean is with a problem like this would drawing two gaussian surfaces, one around each charge, be a good place to start?
 
How do you imagine that we will be able to help you if you do not show us what you did? You need to both describe it in words and show us all your computations. Otherwise it is just not feasible to find where you go wrong.

Edit: You also failed to actually specify what the question asks you to do. You just described the setup.
Just fixed question, my bad.
 

Want to reply to this thread?

"Electric field using Gauss' Law" You must log in or register to reply here.

Related Threads for: Electric field using Gauss' Law

  • Posted
Replies
7
Views
1K
Replies
3
Views
271
Replies
4
Views
2K
Replies
2
Views
1K
Replies
9
Views
831
Replies
1
Views
506
  • Posted
Replies
6
Views
2K
Replies
7
Views
2K

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top