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UPSC 2010: Indiscriminate disposal of used fluorescent electric lamps causes mercury pollution in the environment. Why is mercury used in the manufacture of these lamps?
(a)A mercury coating on the inside of the lamp makes the light bright white
(b)When the lamp is switched on, the mercury in the lamp causes the emission of ultra-violet radiations
(c)When the lamp is switched on, it is the mercury which converts the ultra-violet energy into visible light
(d)None of the statement given above is correct about the use of mercury in the manufacture of fluorescent lamps
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Not attemptedCorrect Answer: (b) When the lamp is switched on, the mercury in the lamp causes the emission of ultra-violet radiations
Inside a fluorescent lamp an electric discharge passes through low-pressure mercury vapour; excited mercury atoms emit predominantly ultraviolet radiation. The UV then strikes the phosphor coating, which fluoresces to visible light. Thus mercury’s role is to produce UV, not to coat the glass or directly convert UV to visible photons. ([zeromercury.org](https://www.zeromercury.org/about-mercury/mercury-in-products/lamps/?utm_source=openai))
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Frequently Asked Questions
What is the correct answer to this UPSC 2010 Science & Technology question?▼
The correct answer is option (b): When the lamp is switched on, the mercury in the lamp causes the emission of ultra-violet radiations. Watch the detailed video explanation in our Sherlocking Prelims course on UnlockIAS.
Which year was this Physics question asked in UPSC Prelims?▼
This question was asked in UPSC CSE Prelims 2010, GS Paper 1, as Question 108. It falls under Science & Technology > Physics.
What is the difficulty level of this UPSC question?▼
This question is rated "moderate". It requires sound conceptual understanding of the topic.
How many UPSC Prelims questions have been asked from Physics?▼
UPSC has asked 104 questions from Physics (under Science & Technology) across multiple years. Visit the topic page to see the full list and year-wise trends.