Capacitance of four metal plates

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Homework Help Overview

The problem involves determining the equivalent capacitance between two points, A and B, in a system of four identical parallel metal plates arranged in air. The external plates are connected by a wire, and the configuration suggests a need to analyze the connections and potential differences between the plates.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the identification of nodes and the arrangement of capacitors formed by the plates. There are attempts to visualize the connections and potential differences, with some questioning the reasoning behind the arrangement and the implications of the plates being at the same potential.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the capacitor arrangement. Some have suggested numbering the capacitors and considering charge distributions to aid in understanding the setup. There is no explicit consensus yet, but various lines of reasoning are being examined.

Contextual Notes

Participants are working under the constraints of the problem as presented, with a focus on the relationships between the plates and the implications of their connections. There is an emphasis on recognizing the capacitors formed by the plates and understanding their configurations.

Patrikp
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Homework Statement


Four identical parallel metal plates with area $$S$$ and distance between each two $$d$$ are located in air. The external plates are connected by wire. What is the equivalent capacitance between A and B?
This is problem from Irodov.

Homework Equations


$$q=UC$$[/B]

The Attempt at a Solution


Plates 1 and 4 are always on same potential which I am not sure how to use.
I tried to simplify as on the picture but that turns out to be wrong(why?).

[/B]
 

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As I see it there are three nodes, A, B and C (the wire connecting the outer plates 1 and 4).

Draw the three nodes on paper. There is capacitance between...

A and B
A and C
B and C
 
CWatters said:
As I see it there are three nodes, A, B and C (the wire connecting the outer plates 1 and 4).

Draw the three nodes on paper. There is capacitance between...

A and B
A and C
B and C
Can you explain how did you get that? Thanks
 
You have to recognize the 3 capacitors, its easier if you number them, say capacitor plate 1,2,3 and 4 , so the 3 capacitors are (12),(23) and (34), now try figuring out the the arrangement of these capacitors, by considering which are connected and which are not.
Patrikp said:
Can you explain how did you get that?
If you want to know how to recognize the 3 capacitors try giving the plates charges, imagine A is the +ve terminal and see which all plates should have +ve and which -ve, once you figure that out, i think you'll be able to get the answer.
 
Patrikp said:
Can you explain how did you get that? Thanks

Try..

image.jpg


PS the colours don't mean anything they are just to highlight the three nodes.
 

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