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

AI Thread Summary
To calculate the resistance of a copper sheet, the formula R = ρL/A is used, where ρ is the resistivity, L is the length, and A is the cross-sectional area. Given a volume of 1 cm³ and a thickness of 0.5 mm, assumptions about the sheet's shape are necessary to determine L and A. The discussion highlights that the resistance also depends on the orientation of the current flow through the sheet. For a rectangular piece of copper, if the current flows along the longest dimension, the resistance can be calculated accordingly. Understanding these parameters is crucial for accurate resistance calculations in conductive materials.
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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