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

Spherical conducting shell?

Consider a thin spherical shell of radius 14.5 cm with a total charge of +39.1 micro coulombs distributed uniformly on its surface. (Take radially outward as the positive direction.)
(b) Find the electric field 39.6 cm from the center of the charge distribution.

Round your answer to three significant figures.

...shouldn't the electric field at this point be given by E = k * (q / r ^ 2), where q is 3.91 x 10 ^ -6 C and r is 0.396 m? Same as a point charge right?
It wants the answer in megaNewtons / Coulomb; I give 2.24 MN/C and it's wrong? Why?

Thanks for any input.
 

Answers and Replies

Physics Monkey
Science Advisor
Homework Helper
1,363
34
Your formula for the field is certainly correct since the charge is distributed uniformly on the shell and you're looking outside the shell. The only thing I can see is that in your post you say you used the value q = 3.91*10^-6 C when in fact 39.1 micro coulombs would be q = 39.1*10^-6 C. Maybe this is just a typo, or maybe that's your problem.
 

Related Threads for: Spherical conducting shell?

  • Last Post
Replies
4
Views
922
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
8
Views
8K
Replies
2
Views
15K
  • Last Post
Replies
5
Views
4K
  • Last Post
Replies
8
Views
988
Top