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M0CNL > TECH 23.05.06 03:52l 74 Lines 2424 Bytes #999 (0) @ WW
BID : E00499M0CNL
Read: DL1LCA GUEST
Subj: Re: Possible error in ARRL Handboo
Path: DB0FHN<DB0RGB<DB0MRW<DK0WUE<SP7MGD<7M3TJZ<ZL2BAU<GB7YKS<GB7SYP<GB7ESX<
GB7COS
Sent: 060523/0231Z @:GB7COS.#31.GBR.EU #:31971 [Essex, Point Clear] FBB7.00i
From: M0CNL@GB7COS.#31.GBR.EU
To : TECH@WW
VK2ZRG WROTE:
> Possible error in the ARRL Handbook.
>
> I've been collecting data on the resistance of various metals over the
> past few days. I couldn't find anything on chromium in the reference books
> I usually use, so I had a look in the ARRL Handbook. Chromium was listed
> in Table 2 of chapter 2 but I was amazed when I saw it listed as having
> just 1.8 times the resistance of copper. I know that silver has the lowest
> resistivity, then copper, gold and aluminium next. But chromium only
> slightly more resistive than aluminium I thought, no way, they've got to
> joking.
> So I looked up chromium in my encyclopedia and found that the electrical
> conductivity of pure chromium was given as 12.2% that of copper. That means
> that it has around 8.1 times the resistance of copper NOT 1.8 times.
>
> Just for fun I looked up the resistance table in the first copy of
> the ARRL Handbook that I bought the year I gain my amateur licence.
> Lo and behold, there was the same figure of 1.8 times the resistance of
> copper. So is the ARRL book right or the encyclopedia?
>
> Has anyone got listings of metal resistivities other than the ARRL book
> to confirm either 1.8 or 8.1 times?
This is the info I found:
Table of resistivities at 293.15 kelvins (20 degrees Celsius)
Material Resistivity (ohm metres) Temperature coefficient per kelvin
Silver 1.59 x10-8 .0061
Copper 1.673 x10-8 .004041
Gold 2.44 x10-8 ?
Aluminium 2.65 x10-8 .004308
Tungsten 5.6 x10-8 .0045
Iron 9.66 x10-8 .00651
Steel Stainless 7.2 x10-7 ?
Platinum 1.1 x10-7 .003927
Chromium 1.8 x10-7 .0000059
Lead 2.2 x10-7 ?
Manganin 4.82 x10-7 .000002
Mercury 9.8 x10-7 .0009
Brass 7 x10-6 .002
Nichrome (Ni,Fe,Cr alloy commonly used in heating elements)
1.50 x10-6 .0004
Constantan Cu,Ni alloy
4.9 x10-5 .000002
Tin 1.15 x10-5 .0042
Silver, German 3.3 x10-5 .0004
Carbon* 3.5 x10-5 -.0005
Seawater 2.0 x10-1 ?
Germanium* 4.6 x10-1 -.05
Silicon* 6.40 x10+2 -.07
Pure water 2.5 x10+5 ?
Sulfur 2 x10+15 ?
Quartz (fused) 7.5 x10+17 ?
* The resistivity of semiconductors depends strongly on the presence of
impurities in the material, a fact which makes them useful in solid state
electronics.
I Hope some of these are usefull
All The Best
Paul
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