Discussion
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 semiconductor 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 ?
Answer: C
Statements 1 and 3 are correct, so the answer is 1 and 3 only.
A CFL is a fluorescent tube folded into a compact shape: an electric discharge through mercury vapour gives ultraviolet light, which the phosphor coating turns into visible light (1). An LED produces light directly from a semiconductor junction. Because an LED wastes far less energy as heat, it gives more light per watt, so a CFL is the less energy-efficient of the two (3).
Statement 2 is the wrong one. An LED lamp typically lasts around 25,000 hours or more, several times the 8,000 to 10,000 hours of a typical CFL, so the CFL's life span is shorter, not longer. Any option including 2 fails.
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