Power is the work done when electrons flow through a circuit. In a good conductor there are lots of free electrons and so little power is consumed. However, when resistance is present, work has to be done to release sufficient electrons for the required current to flow. This generates heat as wasted energy. By combining Ohm's Law and the formula for finding circuit power P then twelve resulting equations can be developed. Select the appropriate formula to determine the power rating of a resistor in a DC circuit. TEST YOUR UNDERSTANDING: DC Power calculations are useful when determining the physical size of a component to ensure it can handle the circuit demands made upon it. The calculations here relate to resistor power ratings. Search online to find suitable power rating of resistor preferred value lists from component suppliers. Note how the physical size relates to the power rating. Also explore the use of wire wound types and why they are only suitable for non-inductive applications.
