Electric field inside a slab of with constant charge density.

  • Thread starter theBEAST
  • Start date
  • #1
364
0

Homework Statement


I have attached the question in a picture. I also attached a picture a drew as my attempt at understanding the question.


Homework Equations


flux = EA = Qenclo


The Attempt at a Solution


So I am not sure how to interpret this question. Is the charge distributed uniformly? If it is then it can be very difficult to solve as you can see in my diagram the electric field goes every where.

Instead of a cylinder I was thinking of using a sphere as my surface... Does that even make sense?


Here is an answer I found online:
http://answers.yahoo.com/question/index?qid=20100124155001AAmSOpU

Do you guys agree? I notice the solution only used the top and bottom area of the gaussian surface...
 

Attachments

  • Capture.PNG
    Capture.PNG
    22.5 KB · Views: 488
  • photo (7).JPG
    photo (7).JPG
    39.2 KB · Views: 436

Answers and Replies

  • #2
BruceW
Homework Helper
3,611
120
usually, the slab is taken to be infinitely (or at least, very) wide in the x and y planes. So using symmetry, what do you think would be the electric field component in the direction of the cylinder's curved side?
 
  • #3
364
0
usually, the slab is taken to be infinitely (or at least, very) wide in the x and y planes. So using symmetry, what do you think would be the electric field component in the direction of the cylinder's curved side?

It seems like it should be zero, if it isn't it's extremely difficult to solve.... But I don't know why...?
 
  • #4
BruceW
Homework Helper
3,611
120
Yeah, its zero. When I was doing undergraduate physics, the explanation they offered was that due to symmetry, it will be zero. If you think about the situation, it would be hard to imagine how the electric field in this direction would be non-zero, while still keeping the symmetry of the problem.

I guess to do this problem properly, you could use rigorous mathematical arguments about symmetry groups. But that is stuff beyond most physics undergraduates, so an intuitive explanation is OK.
 

Related Threads on Electric field inside a slab of with constant charge density.

Replies
2
Views
3K
Replies
4
Views
31K
Replies
1
Views
2K
  • Last Post
Replies
0
Views
5K
  • Last Post
Replies
10
Views
8K
  • Last Post
Replies
5
Views
3K
Replies
2
Views
641
Replies
1
Views
855
Top