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UPSC 2011: What is the difference between a CFL and an LED lamp? 1. To produce light, a CFL uses mercury vapour and phosphor while an LED lamp uses semi-conductor material. 2. The average life span of a CFL is much longer than that of an LED lamp. 3. A CFL is less energy-efficient as compared to an LED lamp. Which of the statements given above is/are correct?
(a)1 only
(b)2 and 3 only
(c)1 and 3 only
(d)1, 2 and 3
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Not attemptedCorrect Answer: (c) 1 and 3 only
1. CFLs generate light from an electric discharge in mercury vapour that excites a phosphor, whereas LEDs use a semiconductor junction—statement 1 is true. 2. Typical CFL life is 8 000–15 000 h, while LEDs last 25 000–35 000 h, so LEDs (not CFLs) have the longer lifespan—statement 2 is false. 3. LEDs use about 25–30 % less energy than CFLs for the same lumens, making CFLs less efficient—statement 3 is true. Therefore statements 1 and 3 only are correct (option c). ([greenamerica.org](https://www.greenamerica.org/green-living/cfls-vs-leds-better-bulbs))
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Frequently Asked Questions
What is the correct answer to this UPSC 2011 Science & Technology question?▼
The correct answer is option (c): 1 and 3 only. Watch the detailed video explanation in our Sherlocking Prelims course on UnlockIAS.
Which year was this Energy & Environment question asked in UPSC Prelims?▼
This question was asked in UPSC CSE Prelims 2011, GS Paper 1, as Question 64. It falls under Science & Technology > Energy & Environment.
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 Energy & Environment?▼
UPSC has asked 48 questions from Energy & Environment (under Science & Technology) across multiple years. Visit the topic page to see the full list and year-wise trends.