Resistivity of tungsten down to -40degC

[cupoftea]

Hi,
All web pages only give tungsten resistivity down to 20degC.
Do you know it down to -40degC?

Also, is this tungsten IR lamp have a filament made of tungsten?

Infra Red 118mm 500 watt Slim Ruby R7s Patio Heater Light Bulb

www.lamps2udirect.com

..its "datasheet" doesnt say.

 

[wwfeldman]

according to
Lide, D. CRC Handbook of Chemistry and Physics, 75 edition. CRC Press, 1995: 12.
at

Resistivity of Tungsten - The Physics Factbook

hypertextbook.com

"electrical resistivity of tungsten RW in n-ohm·m are given in
RW = 48.0 (1 + 4.8297 × 10−3 T + 1.663 × 10−6 T2)"

i added the last parenthesis
interesting unit - looks like nano ohm meters to me


this website talks about the temperature coefficient of resistivity

20.3 Resistance and Resistivity – College Physics

pressbooks.online.ucf.edu

as does this one:

Resistivity and Conductivity - Temperature Coefficients Common Materials

Resistivity, conductivity and temperature coefficients for common materials like silver, gold, platinum, iron and more..

www.engineeringtoolbox.com

 

[FvM]

In a first order estimation, resistance of pure metals is proportional to absolute temperature, surely sufficient accurate for your problem.

 

[crutschow]

All web pages only give tungsten resistivity down to 20degC.
Do you know it down to -40degC?

According to my extrapolation of the tungsten resistance curve, at -40°C it should be about 73% of the value at 20°C.

Also, is this tungsten IR lamp have a filament made of tungsten?

I would expect so, but it could also be an alloy like NiChrome, used in may heating elements such as toasters and stove tops.