[SI-LIST] Re: Resistance
- From: Ray Anderson <Raymond.Anderson@xxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Mon, 13 Aug 2001 13:09:08 -0700 (PDT)
The number he meant to quote was 5.8e+7 which is conductivity (sigma)
in Siemens/meter
The nominal resistivity of copper is about 1.7241e-8 ohm-meters (the reciprocal
of
sigma)
Low resistivity equates to high conductivity.....
-Ray
>
>Hi Mick!
>
>Aside from the differences (plated vs anealed, pure vs alloyed and layered)
>others have pointed out, is it possible you had a sign error in your
>calculations? resistivities for copper are in the mid e+7s not e-7s as you
>have below.
>
>Aubrey Sparkman
>Signal Integrity
>Aubrey_Sparkman@xxxxxxxx
>(512) 723-3592
>
>
>> -----Original Message-----
>> From: Zhou, Xingling (Xingling) [mailto:xlzhou@xxxxxxxxx]
>> Sent: Monday, August 13, 2001 9:07 AM
>> To: Si-List (E-mail)
>> Subject: [SI-LIST] Resistance
>>
>>
>>
>> Hi,
>>
>> When you calculate the DC resistance of wires and traces,
>> which resistivity
>> values should be used or more practical ? Most books give
>> 1/5.8e-7 = 1.724e-8 for pure cooper. However, Dr. Johnson's book gives
>> 6.787e-7 (p.411) and he explained his reasons. On p.409, he
>> mentioned that "
>> the authors have used MathCad to evaluate each of the
>> following formulas in
>> well-known test cases...". Obviously, the
>> two values are quit different, three times ! So, please provide your
>> suggestion ?
>>
>> Thanks.
>>
>> Mick
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>
>
>
>
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