Nonconductive wall with charge density and finding electric field

AI Thread Summary
A nonconducting wall with a uniform charge density of 13.62 μC/cm² is being analyzed to find the electric field 5.7 cm in front of it. The discussion highlights confusion regarding the application of Gauss's law and the appropriate formula for calculating the electric field due to a uniformly charged infinite plane, specifically E = σ/2ε. Participants express frustration over the lack of lecture coverage on this topic and the absence of clear problem parameters. One contributor mentions an attempt to calculate the electric field but received an incorrect answer, suggesting potential issues with significant figures or unit conversions. The conversation emphasizes the need for clarity in understanding electric fields related to charge density in nonconductive materials.
Dtails
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Homework Statement


A nonconducting wall carries a uniform
charge density of 13.62 μC/cm2.
What is the electric field 5.7 cm in front of
the wall? Answer in units of N/C.



Homework Equations


Gauss's law...?


The Attempt at a Solution


Honestly, this bugger's got me scratching my head since our prof never even mentioned it in lecture, and I'm trying to get the homework done a week ahead of time. I've looked around for the relation of electric field to charge density...and it's not been pretty. I tried E=Q/e where little e is our freespace constant, but that's wrong, so I'm not seeing this right.

And I've searched everywhere on the web and not one god damned how-to for this type of problem. Anybody want to be merciful?
 
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Are you told the dimensions of the wall? Or are you supposed to assume that it is "very large"?

If you are 5.7 cm from a "very large wall", it essentially looks like an infinite plane doesn't it?...Surely you've calculated the field due to a uniformly charged infinite plane in your lectures?:wink:
 
You'd be amazed just how bad my prof is. We haven't. And the problem is the problem word for word. Just told it has a uniform charge density, and to find the electric field.

I did try E=σ/2ε. Shot down my answer twice with it. :/
 
Dtails said:
I did try E=σ/2ε. Shot down my answer twice with it. :/

Did you make sure to convert your answer to units of N/C? What was your answer?
 
769491 was the latest one. I take care of the coulomb and meter conversions when I punch through the calculations, so I'm not sure what exactly is up with this problem. Since the answer is rather large it might just be anal about significant figures of some sort since it doesn't define any freespace constants, as they usually do. Blah...
 
Dtails said:
769491 was the latest one.

You seem to be missing about 4 zeroes from the end of that!
 
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