ABSTRACT
Heaters are o en de ned as devices that produce heat or, equivalently, as devices that can heat their surroundings; with such broad de nitions, since heat release is associated with all dissipative processes, all practical devices would be heaters (e.g., resistors, tires, personal computers, etc.). As an extreme example, though there is no dissipation in an “ideal” capacitor, “real” capacitors would also be heaters because of their parasitic resistances. It is therefore better to qualitatively de ne heaters as devices that effi ciently heat their surroundings; despite the intrinsic vagueness of this de nition (how e ciently should a device heat its surroundings to qualify?), it allows to focus on a crucial point: heaters transform an input signal (energy) into heat and, in most cases, it is important that this transformation be as e cient as possible.
