How Do You Calculate the Resistance of a Copper Sheet Given Its Dimensions?

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Homework Help Overview

The discussion revolves around calculating the resistance of a copper sheet given its dimensions and resistivity. The original poster is working with a specific volume of copper and its thickness, questioning how to derive the length and area necessary for the resistance calculation.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to apply the formula for resistance but expresses uncertainty about deriving length and area from the given volume and thickness without assuming a specific shape. Other participants question how the resistance might vary based on the orientation of the current flow through the copper piece.

Discussion Status

Participants are exploring different interpretations of the problem, particularly regarding the assumptions needed to calculate resistance based on the dimensions provided. There is an acknowledgment of the dependency of resistance on the direction of current flow, indicating a productive line of inquiry.

Contextual Notes

The original poster is constrained by the requirement to calculate resistance from a specific volume and thickness, raising questions about the assumptions regarding the shape of the copper sheet.

T7
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Hi,

Part of a question I am working on asks me to "calculate the resistance of 1cm^3 of copper in the form of a thin sheet 0.5mm thick (between the faces of the sheet), given a resistivity of 1.69x10^-8 Ohm metres".

Given that p = RA/L, it is clear that R = pL/A = 1.69x10^-8 x L/A. So far, so good. But I am not sure that I can obtain L and A from merely a volume (1cm^3) and a thickness without making some assumption about its shape (a square sheet, perhaps)? Am I missing something?

Thanks!
 
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T7,

What's the resistance of a 1cm x 2cm x 3cm piece of copper?
 
jdavel said:
T7,

What's the resistance of a 1cm x 2cm x 3cm piece of copper?

Doesn't it depend on which side the current is going through (ie. which sides make up the area)?
 
t7,

"Doesn't it depend on which side the current is going through (ie. which sides make up the area)?"

Absolutely! So, let's say the current is in the direction of the longest dimension (3cm). What's the resistance of that "wire"?
 

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