Electric field point charges

  • Thread starter tuggler
  • Start date
  • #1
45
0

Homework Statement



Two points are resting on a string. The first point is resting at x = 6.0 m and has charge q1 =−7.1 µC. The second point is resting at x = −4.0 m and has charge q2 = −4.3 µC.
At what location is the total electric field zero from the two points(other than infinity)?


Homework Equations



[tex]E =\frac{KQ}{r^2}[/tex]

[tex]\frac{q_1}{r_1^2} = \frac{q_2}{r_2^2}[/tex]



The Attempt at a Solution



I divided away the constant K from my second equation because they cancel out when you set them equal to each other.

I don't know what my [tex]r_1,r_2[/tex] should be here?
 

Answers and Replies

  • #2
33
3
Why don't you set the distance from the first charge x and define the distance from the other with x and the distance between the two charges? Thus you introduce only one variable in one equation.
 
  • #3
20,854
4,544
Don't forget that the contribution to the electric field from each charge has direction, so, if the point is between the two charges, the contribution from the charge at x = 6 is pointing in the negative x-direction, and the contribution from the charge at x = -4 is pointing in the positive x-direction.
 
  • #4
45
0
I am not following can you guys elaborate more please?
 

Related Threads on Electric field point charges

  • Last Post
Replies
16
Views
17K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
4
Views
6K
  • Last Post
Replies
4
Views
834
  • Last Post
Replies
1
Views
820
  • Last Post
Replies
1
Views
7K
  • Last Post
Replies
0
Views
866
  • Last Post
Replies
1
Views
3K
  • Last Post
2
Replies
33
Views
4K
  • Last Post
Replies
10
Views
2K
Top