Rectifying my logic of Gauss's Law

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Homework Help Overview

The discussion revolves around the application of Gauss's Law in the context of electric charges distributed in a system involving inner and outer shells. Participants are examining the relationships between the charges and the implications for the electric field within conductors.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are attempting to identify errors in charge calculations and are questioning the specifics of the charge distribution on the shells. There is a focus on understanding how the charges interact and the implications for the electric field within the conductor.

Discussion Status

The discussion is actively exploring different interpretations of the problem, particularly regarding the charge on the inner and outer surfaces of the shells. Some participants have provided guidance on the relationship between the charges, but there is no explicit consensus on the final interpretation.

Contextual Notes

Participants note that the original poster has missed lectures, which may contribute to gaps in understanding the problem's requirements and the application of Gauss's Law. There is an emphasis on ensuring clarity regarding what specific charge the question is asking for.

The Blind Watchmaker
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Homework Statement


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Homework Equations


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The Attempt at a Solution


E4Πr2 = Q/∈0
49000⋅4Π4.12 =Q/∈0
Q = 91.6 μC
Qshell = Q = 91.6 μC
Qshell = Qinner + Qouter
91.6 = -3.3 + Qouter
Qouter = 94.9 μC

Can someone point out the error? I have skipped too many lectures and I am catching up right now. Any help would be appreciated! :)
 

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Pay close attention to the actual question posed! Precisely what charge are they going for?
 
gneill said:
Pay close attention to the actual question posed! Precisely what charge are they going for?
Ah I think I get it. Since the electric field inside a conductor must be 0, there must exist a charge on the inner surface of the larger shell that is equal and opposite to 3.3 μC. Thus, the remaining charge is 91.6 - 3.3 = 88.3 μC. Is this what you are hinting at?
 
The Blind Watchmaker said:
Ah I think I get it. Since the electric field inside a conductor must be 0, there must exist a charge on the inner surface of the larger shell that is equal and opposite to 3.3 μC. Thus, the remaining charge is 91.6 - 3.3 = 88.3 μC. Is this what you are hinting at?
Something like that, but take care... Sure, the inner shell's charge is matched and effectively "cancelled" by the charge on the inner surface of the outer shell. So what remains on the outer surface must be what Gauss's Law "sees" as the contained charge...
 
gneill said:
Something like that, but take care... Sure, the inner shell's charge is matched and effectively "cancelled" by the charge on the inner surface of the outer shell. So what remains on the outer surface must be what Gauss's Law "sees" as the contained charge...
So if the question is asking for the "charge of the larger shell" it would be 91.6 + 3.3 μC, but since this question is only asking for the outer surface, the charge is taken to be 91.6 μC?
 
The Blind Watchmaker said:
So if the question is asking for the "charge of the larger shell" it would be 91.6 + 3.3 μC, but since this question is only asking for the outer surface, the charge is taken to be 91.6 μC?
Right!
 
gneill said:
Right!
It is 3 AM here but thanks!
 

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