Search results
Results from the WOW.Com Content Network
A positive temperature coefficient (PTC) refers to materials that experience an increase in electrical resistance when their temperature is raised. Materials which have useful engineering applications usually show a relatively rapid increase with temperature, i.e. a higher coefficient.
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.
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.
The two types of diode are in fact constructed in similar ways and both effects are present in diodes of this type. In silicon diodes up to about 5.6 volts, the Zener effect is the predominant effect and shows a marked negative temperature coefficient. Above 5.6 volts, the avalanche effect dominates and exhibits a positive temperature coefficient.
A heating element is a device used for conversion of electric energy into heat, consisting of a heating resistor and accessories. [1] Heat is generated by the passage of electric current through a resistor through a process known as Joule heating.
The main feature of thermodynamic diagrams is the equivalence between the area in the diagram and energy. When air changes pressure and temperature during a process and prescribes a closed curve within the diagram the area enclosed by this curve is proportional to the energy which has been gained or released by the air.
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 .