Although the result may be less evident or imperceptible, exactly the same process of energy conversion goes on when current flows through any electronic component. The power output of a lamp, resistor, or other component, is defined as the rate of change of electrical energy to heat, light, or some other form of energy. 0.6 W of heat are generated in this resistor. To prevent overheating, it must be possible for heat to be lost, or dissipated , to the surroundings at the same rate. A resistor's ability to lose heat depends to a large extent upon its surface area.
Larger resistors dissipate heat more effectively.
Some resistors are designed to pass very large currents and are cased in aluminium with fins to increase surface area and promote heat loss. Input and signal processing subsystems in electronic circuits rarely involve large currents, but power rating should be considered when circuits drive output transducers, such as lamps, LEDs, and loudspeakers. Up Go to Checkpoint .