Context: To improve the efficiency of the lamp, the filament usually consists of multiple coils of coiled fine wire, also known as a 'coiled coil'. For a 60-watt 120-volt lamp, the uncoiled length of the tungsten filament is usually 22.8 inches (580 mm), and the filament diameter is 0.0018 inches (0.046 mm). The advantage of the coiled coil is that evaporation of the tungsten filament is at the rate of a tungsten cylinder having a diameter equal to that of the coiled coil. The coiled-coil filament evaporates more slowly than a straight filament of the same surface area and light-emitting power. As a result, the filament can then run hotter, which results in a more efficient light source, while reducing the evaporation so that the filament will last longer than a straight filament at the same temperature.

Question: How long is a typical uncoiled tungsten filament for a 60-watt bulb?
Answer: 22.8 inches

Question: What is the advantage of a coiled-coil filament over a straight filament?
Answer: The coiled-coil filament evaporates more slowly

Question: What positive effects does a slower-evaporating filament enable?
Answer: more efficient light source

Question: What is the typical diameter of the filament on a 60-watt bulb?
Answer: 0.0018 inches

Question: What did not improve efficiency of the lamp?
Answer: Unanswerable

Question: How long is a typical uncoiled tungsten filament for a 40-watt bulb?
Answer: Unanswerable

Question: What are the disadvantage of the coiled coil vs a straight filament?
Answer: Unanswerable

Question: What negative effects does a slower evaporating filament cause?
Answer: Unanswerable