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The Callendar–Van Dusen equation is an equation that describes the relationship between resistance (R) and temperature (T) of platinum resistance thermometers (RTD). As commonly used for commercial applications of RTD thermometers, the relationship between resistance and temperature is given by the following equations.
Common RTD sensing elements for biomedical application constructed of platinum (Pt), nickel (Ni), or copper (Cu) have a repeatable, [b] resistance versus temperature relationship (R vs T) and operating temperature range. The R vs T relationship is defined as the amount of resistance change of the sensor per degree of temperature change. [1]
(room temperature) (alpha, polycrystalline) calculated 562 nΩm CRC (10 −8 Ωm) ... 78 Pt platinum; use 19.22 nΩm 96 nΩm 105 nΩm 107 nΩm 108 nΩm
Platinum has excellent resistance to corrosion. Bulk platinum does not oxidize in air at any temperature, but it forms a thin surface film of PtO 2 that can be easily removed by heating to about 400 °C. [17] [18] The most common oxidation states of platinum are +2 and +4. The +1 and +3 oxidation states are less common, and are often stabilized ...
At high temperatures, the resistance of a metal increases linearly with temperature. As the temperature of a metal is reduced, the temperature dependence of resistivity follows a power law function of temperature. Mathematically the temperature dependence of the resistivity ρ of a metal can be approximated through the Bloch–Grüneisen ...
When temperature-dependent resistance of a component is used purposefully, the component is called a resistance thermometer or thermistor. (A resistance thermometer is made of metal, usually platinum, while a thermistor is made of ceramic or polymer.) Resistance thermometers and thermistors are generally used in two ways.
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Werner von Siemens was the first to propose the use of a platinum resistance temperature detector in 1860, although his instrument readings were unstable. [2] Callendar developed an equation for the resistance of metal as a function of temperature, which was accurate to within 1% from 0-600 °C. [2]