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The equation model converts the resistance actually measured in a thermistor to its theoretical bulk temperature, with a closer approximation to actual temperature than simpler models, and valid over the entire working temperature range of the sensor.
As commonly used for commercial applications of RTD thermometers, the relationship between resistance and temperature is given by the following equations. The relationship above 0 °C (up to the melting point of aluminum ~ 660 °C) is a simplification of the equation that holds over a broader range down to -200 °C.
The typical operating temperature range of a thermistor is −55 °C to +150 °C, though some glass-body thermistors have a maximal operating temperature of +300 °C. Thermistors differ from resistance temperature detectors (RTDs) in that the material used in a thermistor is generally a ceramic or polymer, while RTDs use pure metals. The ...
Copper has a very linear resistance–temperature relationship; however, copper oxidizes at moderate temperatures and cannot be used over 150 °C (302 °F). [citation needed] The significant characteristic of metals used as resistive elements is the linear approximation of the resistance versus temperature relationship between 0 and 100 °C.
The SI unit of absolute thermal resistance is kelvins per watt (K/W) or the equivalent degrees Celsius per watt (°C/W) – the two are the same since the intervals are equal: ΔT = 1 K = 1 °C. The thermal resistance of materials is of great interest to electronic engineers because most electrical components generate heat and need to be cooled.
The defining equation for thermal conductivity is =, where is the heat flux, is the thermal conductivity, and is the temperature gradient. This is known as Fourier's law for heat conduction. Although commonly expressed as a scalar , the most general form of thermal conductivity is a second-rank tensor .
The Year Without a Santa Claus, a Christmas special from Jules Bass and Arthur Rankin, Jr., turns 50 this December. The beloved special was adapted from the book of the same name by Phyllis ...
The lower the coefficient, the greater a decrease in electrical resistance for a given temperature increase. NTC materials are used to create inrush current limiters (because they present higher initial resistance until the current limiter reaches quiescent temperature), temperature sensors and thermistors.