Difference between Resistance and resistivity

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Discussion Overview

The discussion revolves around the distinction between resistance and resistivity, focusing on their definitions, properties, and implications in the context of materials and devices. Participants explore theoretical and conceptual aspects of these electrical properties.

Discussion Character

  • Conceptual clarification
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant defines resistivity as a specific property of a material, expressed as E/J, while resistance is described as resistivity over a unit length and area, suggesting that resistance measures resistivity over a volume.
  • Another participant reiterates the relationship between resistance and resistivity, stating that resistance is proportional to length and inversely proportional to area, with resistivity as the proportionality constant.
  • A third participant provides a mechanical analogy, explaining that resistance is a property of a device, whereas resistivity is a property of a material, comparing the differences in strength between aluminum foil and an aluminum baseball bat.
  • A later reply emphasizes that the resistance of a material depends on its dimensions, while resistivity is a more useful concept as it is independent of dimensions and can be referenced from data books.

Areas of Agreement / Disagreement

Participants generally agree on the definitions of resistance and resistivity, but there are nuances in how they relate to material properties and device characteristics. The discussion remains somewhat unresolved regarding the implications of these differences in practical applications.

Contextual Notes

Some participants express uncertainty about their understanding and the definitions provided, indicating a potential reliance on different sources for information. The discussion highlights the importance of context when discussing resistance and resistivity.

SpartanG345
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What is the difference between these 2 quantities?

from my textbook defines resistivity as a specific property of a material
and is = E/J

where the resistance is the resistivity over a unit length and area. So I suppose the resistance is a measures of resistivity over a volume

Resistance = pL/A

thats what i think but i am not sure if i am right

PS i am sorry if this is a noob question, but my answer differed by one provided on yahoo answers, but then again yahoo answers is only yahoo answers( i got worried)
 
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SpartanG345 said:
Resistance = pL/A
This is what you need. Resistance of a piece of material is proportional to its length and inversely proportional to its area. The proportionality constant p is called the resistivity, which is a property of the kind of material.

Read this: http://hyperphysics.phy-astr.gsu.edu/HBASE/electric/resis.html#c2"
 
Last edited by a moderator:
Resistance is a property of a device and resistivity is a property of a material. For a mechanical analogue you might think of the difference in strength between a piece of aluminum foil and an aluminum baseball bat. They are both made out of aluminum, so they both have the same Young's modulus, but they are shaped differently so they have different stiffness.
 
SpartanG345 said:
What is the difference between these 2 quantities?

from my textbook defines resistivity as a specific property of a material
and is = E/J

where the resistance is the resistivity over a unit length and area. So I suppose the resistance is a measures of resistivity over a volume

Resistance = pL/A

thats what i think but i am not sure if i am right

PS i am sorry if this is a noob question, but my answer differed by one provided on yahoo answers, but then again yahoo answers is only yahoo answers( i got worried)

Suppose you set me this question:What is the resistance of aluminium?I would answer that It's a silly question because it depends on the cross sectional area and the length of the aluminium.If you now asked me what is the resistivity of aluminium I would refer to a data book and come back with an answer.Knowing the resistivity and the dimensions of the aluminium it is easy to work out the resistance.Resistivity,therefore, is a much more useful concept because it is a property of the material and independent of its dimensions.
 

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