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A temperature coefficient describes the relative change of a physical property that is associated with a given change in temperature. For a property R that changes when the temperature changes by dT , the temperature coefficient α is defined by the following equation:
Quantity (common name/s) (Common) symbol/s Defining equation SI unit Dimension Temperature gradient: No standard symbol K⋅m −1: ΘL −1: Thermal conduction rate, thermal current, thermal/heat flux, thermal power transfer
in which α is a positive coefficient called the thermal diffusivity of the medium. In addition to other physical phenomena, this equation describes the flow of heat in a homogeneous and isotropic medium, with u ( x , y , z , t ) being the temperature at the point ( x , y , z ) and time t .
The coefficients of the differential quantities are intensive quantities (temperature, pressure, chemical potential). Each pair in the equation are known as a conjugate pair with respect to the internal energy. The intensive variables may be viewed as a generalized "force".
A positive-temperature-coefficient heating element (PTC heating element), or self-regulating heater, is an electrical resistance heater whose resistance increases significantly with temperature. The name self-regulating heater comes from the tendency of such heating elements to maintain a constant temperature when supplied by a given voltage.
In crystal oscillators for temperature compensation, medical equipment temperature control, and industrial automation, silicon PTC thermistors display a nearly linear positive temperature coefficient (0.7%/°C). A linearization resistor can be added if further linearization is needed. [23]
A plot illustrating the dependence on temperature of the rates of chemical reactions and various biological processes, for several different Q 10 temperature coefficients. The rate ratio at a temperature increase of 10 degrees (marked by points) is equal to the Q 10 coefficient. The Q 10 temperature coefficient is a measure of temperature ...
The Van 't Hoff equation relates the change in the equilibrium constant, K eq, of a chemical reaction to the change in temperature, T, given the standard enthalpy change, Δ r H ⊖, for the process. The subscript r {\displaystyle r} means "reaction" and the superscript ⊖ {\displaystyle \ominus } means "standard".