Question

why the bulb of incandescent bulb filled with nitrogen gas​

Answer 1

Answer: i'm guessing because filling a bulb with an inert gas such as argon or nitrogen slows down the evaporation of the tungsten filament compared to operating it in a vacuum

Explanation:  This allows for greater temperatures and therefore greater efficacy with less reduction in filament life.

Answer 2

Answer:

The main reason that bulbs are filled with an inert gas is to reduce evaporation of the filament and prevent its oxidation. The most popularly used filling in electric bulbs is a mixture of Argon and Nitrogen.

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