Charge density on the surface of a conductor

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Homework Help Overview

The discussion revolves around the charge density on the surface of a conductor, specifically addressing the conditions under which the electric field inside the conductor is zero. Participants are exploring the relationships between surface charge densities denoted as σ1 and σ2, as well as the total charge Q on the conductor.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss setting the electric field inside the conductor to zero as a condition for solving the problem. There are mentions of deriving relationships between the unknowns σ1 and σ2, and some participants question the relevance of volume charge density in this context. Others point out potential sign errors in the established relationships.

Discussion Status

The discussion is ongoing, with participants providing guidance on correcting relationships between charge densities and suggesting the need for additional equations based on the total charge Q. There is acknowledgment of previous attempts and a recognition of the complexity involved in resolving the unknowns.

Contextual Notes

Some participants note the absence of a response from the original poster, indicating a potential delay in the discussion's progression. There is also a mention of a misunderstanding regarding the roles of participants in the thread.

marcos7615
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Homework Statement
There is a flat conductor, charge Q, very large surface area S and thickness
“a“ parallel to a surface charge distribution of density σ = 2Q/S
and separated a distance "d" from it, as shown in the figure. It is requested:

- The charge density σ1 on the outer surface of the conductor
of the load distribution.
Relevant Equations
σ = 2Q/S
1653165597565.png


I have tried to solve the problem by setting as a condition that the electric field inside the conductor has to be 0, but in this way I have two unknowns (σ1 and σ2):
1653166686126.png
 
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marcos7615 said:
I have tried to solve the problem by setting as a condition that the electric field inside the conductor has to be 0, but in this way I have two unknowns (σ1 and σ2):
1653168712217.png

Check the signs of the terms on the left side.

Also, you should be able to come up with another relationship between ##\sigma_1## and ##\sigma_2## using the fact that the total charge on the conductor is given to be ##Q##.
 
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Will it look like the picture below?
A12.jpg
 
alan123hk said:
Will it look like the picture below?
I don't understand this picture. Volume charge density ##\rho## is not relevant to this problem.

You made a good start in your first post where you got a relation between the surface charge densities based on the fact that ##E## must equal zero inside the conductor. However, there is a sign error in your relation
1653484077758.png


Once you make the correction, this relation gives you one equation for the two unknowns ##\sigma_1## and ##\sigma_2##. The total charge ##Q## of the conductor and the the charge density ##\sigma## of the plane are considered as known.

Try finding another equation involving ##\sigma_1## and ##\sigma_2## based on the idea that the net charge of the conductor is ##Q##.
 
Sorry I was in a hurry so the description in my previous post was wrong. By the way, I'm not the OP of this thread, I'm just interested in this question.

This is my answer after much deliberation. I believe this time should not go wrong.

A13.jpg
 
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alan123hk said:
By the way, I'm not the OP of this thread, I'm just interested in this question.
Yes, I mistakenly assumed you were the OP. It has been several days without any response from the OP.

Your solution is correct.
 
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