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NiChrome and Resistance Studies
Name: Vishnu
Status: student
Grade: other
Location: VA
Question:
What are the properties (in terms of structure) of
Nichrome wire that makes it perfect for resistance investigations?
Replies:
Hi Vishnu,
I am not at all sure what you mean by "resistance
investigations", but Nichrome wire is far from perfect for
use in resistance measurement. The main attribute of Nichrome
is that, like Kantal and other similar alloys, Nichrome can
withstand very high temperatures without oxidation. Therefore
it is an excellent material to make electrical heating
elements from, that must operate at red-heat. Nichrome's
resistance increases substantially, as its temperature
increases, which makes it relatively useless for making
precision resistance devices.
The main attribute needed in making accurate resistors is
that the resistance of the wire used to make the device, must
not significantly change over temperature. After all, what use
is a resistance measurement "standard", against which you are
comparing unknown resistances, if the "standard" resistor
changes it resistance as temperature changes.
Two alloys that maintain a constant resistivity over a wide
temperature range, and which are commonly to make wire used
in making resistors, and "shunts" (low-value resistors that
are part of an ammeter) are Constantin and Cupron.
Regards,
Bob Wilson.
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Update: June 2012
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