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

Electron field around sphere

1. Homework Statement
A 2.40 -mm-diameter glass sphere has a charge of + 1.70 nC.
What speed does an electron need to orbit the sphere 1.40 mm above the surface?

2. Homework Equations
Electric Field of Sphere: E=k*Q/(r^2)
q*E=M*v^2/r


3. The Attempt at a Solution
It seems pretty straight forward but I must be doing something wrong with the r values. Could someone tell me what the radius is considered. For the electric field is it the radius of sphere + the distance away or what and same for the other equation. Ive tried pretty much all the combos I can think of and still am getting it wrong so not sure where Im going wrong.
 

Answers and Replies

1,860
0
It says above the surface so you would have to add the radius of the sphere to the radius of the orbit.
 
Last edited:

Related Threads for: Electron field around sphere

  • Last Post
Replies
3
Views
6K
Replies
2
Views
10K
Replies
2
Views
1K
Replies
1
Views
5K
  • Last Post
Replies
1
Views
808
  • Last Post
Replies
7
Views
16K
  • Last Post
Replies
2
Views
4K
Top