To produce full brilliance in an incandescent lamp, what temperature must the tungsten filament reach?

The correct choice relates to the fact that an incandescent lamp's tungsten filament must reach a high temperature to emit a bright white light, which is often compared to the brightness of natural sunlight. The typical temperature for a tungsten filament to achieve this brightness is around 5,000 degrees Kelvin. At this temperature, the filament produces a balance of visible light that appears very bright to the human eye, resulting in what is often described as a "full brilliance" in incandescent lighting.

This temperature is significant not only because of the light output but also due to the filament's ability to withstand such heat without melting, which is a critical characteristic of tungsten. Other temperatures listed are either higher or lower than what is considered optimal for brass incandescent lighting, thus impacting the efficiency and quality of light produced.