The conversion of electrical energy into heat is integral to the functioning of any resistor. In most cases the power dissipated is either negligible, or easily allowed for by selection of the appropriate product size. But there are circumstances where temperature rise must be carefully managed. The obvious example is to prevent the overheating of materials within a product, but another is to mitigate the effect of small internal temperature variations on the accuracy of a precision circuit. This webinar will review the principles and pitfalls of designing with regard to the energy output of power resistors, as well as the energy input.