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Anonymous Poster

Resistivity Question

01/10/2011 5:40 AM

Is there any formulae for converting "grams" to "ohms".
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user-deleted-1105
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#1

Re: conversion

01/10/2011 5:46 AM

It's the same formula that converts colour to smell.
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Anonymous Poster
#3
In reply to #1

Re: conversion

01/10/2011 5:49 AM

I am serious,...if 1000 grams copper, how many ohms??
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user-deleted-1105
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#5
In reply to #3

Re: conversion

01/10/2011 6:22 AM

Ah, you've now added the fact that you are talking about copper.
Maybe next you'll tell us what shape this copper will take?
That is also vital information, a long thin wire will have more resistance than a cube.
There is no conversion grams to ohms.
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RDGRNR
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#9
In reply to #1

Re: conversion

01/10/2011 8:47 AM

Is that a cat thing?

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Tornado
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#2

Re: conversion

01/10/2011 5:48 AM

No. Those units are completely incommensurable with each other, and mutually irrelevant. Please look up any of these terms that you may not already know.

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Anonymous Poster
#4

Re: conversion

01/10/2011 6:05 AM

some strange transducer may do your purpose
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PWSlack
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#6

Re: conversion

01/10/2011 6:56 AM

Not without placing that question into some context.

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Anonymous Poster
#7

Re: conversion

01/10/2011 7:29 AM

Nyet.
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fixitorelse
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#8

Re: conversion

01/10/2011 7:37 AM

Someone once told me that there were no stupid questions. I think I have just found out that is not true.
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Anonymous Poster
#13
In reply to #8

Re: conversion

01/10/2011 11:12 AM

same answer was given to those famous persons who invented lot of things usefull to our life. You are legally not certified your birth.
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Usbport
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#10

Re: conversion

01/10/2011 8:50 AM

With a bit of common sense and imagination, yes:

The resistivity, ρ, of copper is 1.68·10-8 ohm·meters.

The density, d, of copper is about 8.98·106 grams/meter3

The Resistance is given by R = ρ· L/A, where L is the Length and A is the Area of the wire. Volume is V = L·A, and Mass is d·L·A. A length of wire 1 meter long will have an Area of A = M/d (in square meters).

So, if you assume a Length of 1 meter for the wire, then R = ρ/A.

So R = ρ·d/M.

Thus, for a length of wire 1 Meter long, the Ohms for a given number of grams is:

R (in Ohms) = (1.68·10-8 · 8.98·106)/M (where M is in grams)

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JRaef
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#11
In reply to #10

Re: conversion

01/10/2011 10:39 AM

Nicely done. I took issue with it at first because I was missing the fact that you accounted for the cross sectional area in your formula.

It still doesn't account for skin effect however. It's a minor issue in comparison yet significant in AC circuits, but of course the OP never qualified the question in that regard.

I wonder if his professor will mark off some points in his homework assignment for not mentioning it?

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user-deleted-1105
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#12
In reply to #11

Re: conversion

01/10/2011 10:50 AM

If his homework answer is written with the same clarity as his post he won't get anything.
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kwcharlie
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#14
In reply to #10

Re: conversion

01/10/2011 11:41 AM

Yes GA but it's like hearing "to be or not to be, that is the question" and telling Hamlet that the question must have been "what is the square root of 4 B squared"

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#15

Re: Resistivity Question

01/10/2011 3:58 PM

This will work for any material:

1) gr=o

2) a=h
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