The incandescent light bulb is a notoriously inefficient way to convert electric power into visible light. The tungsten filament emits blackbody radiation at a temperature that is limited by its melting point. Define the lighting efficiency as the ratio of the power emitted in the visible range (400–750 nm) to the total power emitted. What is the theoretical maximum efficiency of a tungsten light bulb, given that tungsten melts at 3422℃?