Search results
Results from the WOW.Com Content Network
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:
A ceramic heater as a consumer product is a space heater that generates heat using a heating element of ceramic with a positive temperature coefficient (PTC). [1] [2] [failed verification] Ceramic heaters are usually portable and typically used for heating a room or small office, and are of similar utility to metal-element fan heaters.
In this region the device has a small negative temperature coefficient. At the Curie point temperature, the dielectric constant drops sufficiently to allow the formation of potential barriers at the grain boundaries, and the resistance increases sharply with temperature. At even higher temperatures, the material reverts to NTC behaviour.
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.
The spectrum of light produced by an incandescent lamp closely approximates that of a black body radiator at the same temperature. [85] The basis for light sources used as the standard for color perception is a tungsten incandescent lamp operating at a defined temperature. [86] Spectral power distribution of a 25 W incandescent light bulb.
The first term has a negative temperature coefficient; the second term has a positive temperature coefficient (from its ). By an appropriate choice of N {\displaystyle N} and R 1 {\displaystyle R1} and R 2 {\displaystyle R2} , these temperature coefficients can be made to cancel, giving an output voltage that is nearly independent of temperature.
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".
Chemical reactions involving thermal runaway are also called thermal explosions in chemical engineering, or runaway reactions in organic chemistry.It is a process by which an exothermic reaction goes out of control: the reaction rate increases due to an increase in temperature, causing a further increase in temperature and hence a further rapid increase in the reaction rate.