Question

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Answer 1

Stays the same, as far as I understand this question. Ordinary light bulbs work by simply heating a tungsten filament until it glows. The filament acts very much like a black body, so the amount of energy in visible and infrared (heat) radiation is determined just by the temperature of the filament. If you're asking questions about how the resistivity of the filament changes over time, so that the same applied voltage might change the current, and hence the temperature, this is a more subtle question.