___ is the ratio of the actual power delivered by a load divided by the input power required by the load to operate.

The correct answer is efficiency, which is defined as the ratio of the actual power delivered by a load (output power) divided by the input power required by the load to operate. This concept is crucial in electrical engineering and energy management because it quantifies how well an electrical device converts input energy (usually electrical energy) into usable output energy (like mechanical energy, heat, etc.).

Efficiency is typically expressed as a percentage. For example, if a machine consumes 100 watts of input power and delivers 80 watts of output power, its efficiency would be 80%. This indicates that 80% of the input power is effectively used, while the rest may be lost as inefficiencies through heat, sound, or other forms of energy dissipation.

Understanding efficiency is important for evaluating and improving the performance of electrical systems, as well as for selecting equipment that minimizes energy consumption while maximizing output.