# resistance of various metals

Discussion in 'Electronic Basics' started by Chris W, Feb 25, 2008.

1. ### Chris WGuest

I have seen charts that show how the resistance of various metals
compare. What I haven't seen is a way to make determine how much larger
say a stainless steel rod would need to be to have the same resistance
as a copper rod of some given diameter. For example if I had a 30 awg
copper wire and a 1" dia Stainless steel rod, even though the copper is
a better conductor, in this case the 1" dia stainless steel rod is going
to have less resistance. Is there a rule of thumb, or chart that tells
how much larger to make a conductor to have equivalent resistance to copper?

--
Chris W
KE5GIX

"Protect your digital freedom and privacy, eliminate DRM,

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2. ### Phil AllisonGuest

"Chris W"

** Are you for real ????

Got no idea that a wire's or rod's resistance is * inversely proportional *
to its cross sectional area ?

Ever figure out that two similar wires run in parallel have half the
resistance of one ???

** A real dope -

even by the most humble standards of ham operators.

........ Phil

3. ### Al ForsterGuest

"Chris W" wrote in message news:20vwj.5938\$...
No chart that I'm aware of, but not difficult to calculate. Find a
table of resistivities for metals eg
http://en.wikipedia.org/wiki/Electrical_resistivity#Table_of_resistivitiesand calculate fromResistance = (resistivity * length) / x-sectional area.Hope this helpsAl

4. ### ChrisGuest

Easy to calculate from the equation Al gave. Total resistance is the
same, total length is the same, so if you have a material that's eight
times the resistivity, by the equation it will have to have eight
times the cross-sectional area. Simple algebra.

Which means the resistivity chart the OP is looking at is actually the
chart he needs -- if he has a calculator, he can divide the
resistivity of stainless steel by the resistivity of copper, and that
tells him how many times more cross-sectional area he needs.

And a newbie alert if Chris is doing the calculations to determine
Charts for resistivity are frequently expressed for CM, circular
mils. One circular mil is the area of a circle 1 mil in diameter.
This is *not* 1 square mil -- you need to convert!

http://en.wikipedia.org/wiki/Circular_mils

Chris

5. ### Don KlipsteinGuest

#Table_of_resistivities

You will have to look up or determine the resistivity of your specific
stainless steel - there are a lot of different stainless steels.

- Don Klipstein ()