Question

Which of the following gas is used to fill electric bulbs?
A. Argon
B. Nitrogen
C. Helium
D. Oxygen

Answer 1

Hint: Filling a bulb with an inert gas slows down the evaporation of the tungsten filament compared to operating it in a vacuum. This allows for greater temperatures and therefore greater efficacy with less reduction in filament life.

Complete step-by-step answer:
Argon is a commonly used gas, used to fill incandescent light bulbs. It increases the bulb life by preventing the tungsten filament from deteriorating too quickly. Other gases such as helium, neon nitrogen and krypton are also used in lightning.

So, among the mentioned options the correct answer is Option A.

Inert gases are reactive towards the burning filament of the bulb. Therefore we have to use either inert gases like Argon or inactive nitrogen.

In the option it is mentioned as nitrogen which is active and can react with the burning filament so it is not the correct answer.

Note: A light bulb full of oxygen would not work well as the bulb’s tungsten filament if it is ignited that all would burn very brightly and short out quickly. Furthermore, once charged through with electricity, the bulb’s oxygen content might make the filaments and bulb explode.

Helium is not used in the incandescent light bulbs because it is expensive and there are other cheaper gases which are better for the job. The high thermal conductivity of helium helps cool the LED filaments in the absence of a metal heat sink.