UPSC CSE Prelims
Question 51
What is the difference between a CFL and an LED lamp?
- To produce light, a CFL uses mercury vapour and phosphor while an LED lamp uses semi-conductor material.
- The average life span of a CFL is much longer than that of an LED lamp.
- A CFL is less energy-efficient as compared to an LED lamp.
Which of the statements given above is/are correct?
View correct answer and explanation
Correct answer: C
Correct Option: C
Explanation: A CFL produces light from an electric discharge through mercury vapour and phosphor coating; an LED uses electroluminescence in a semiconductor, usually more efficiently and for longer.
Statement / Item-wise Analysis:
1: Correct - Correct: CFLs contain mercury vapour and phosphor, LEDs use semiconductor junctions.
2: Incorrect - Incorrect: LEDs generally last much longer than CFL lamps.
3: Correct - Correct: LED lamps typically deliver more light per watt than comparable CFLs.
Option-wise Analysis:
A: Incorrect - omits supported item 3.
B: Incorrect - includes unsupported item 2; omits supported item 1.
C: Correct - includes the supported statements and excludes the unsupported ones.
D: Incorrect - includes unsupported item 2.