Consider the following statements: An ordinary light bulb has a rather short life because the:1. filament wire is not uniform.2. bulb cannot be evacuated completely.3. wires supporting the filament melt at high temperatures.Which of the above statements are correct?
✓ Correct answer: d) 1, 2 and 3
ExplanationStatement 1 is correct: The filament in a light bulb is typically made of tungsten.When the filament is not uniform , the thinner sections tend to heat up more, leading to higher temperatures and stress, which can cause premature failure.Statement 2 is correct: Light bulbs typically contain an inert gas, like argon, to prevent oxidation of the filament and improve lifespan.Complete evacuation of the bulb is not possible.A small quantity of gases left behind which expands on heating by heat through filament.If the bulb is not evacuated properly, the filament would burn out quickly causing the bulb to have a short life.Statement 3 is correct: The wires supporting the filament are designed to withstand high temperatures.However if they are not robust enough or if the filament heats up too much, and they can melt, causing the bulb to fail.278
Practice more Science PYQs
Attempt a free 10-question quiz or browse the full Science & Technology previous-year-question bank with instant answers and explanations.
🔬 Science PYQs →