Q. 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 lifespan 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? (UPSC Prelims 2011)
Answer:
1 and 3 only
Notes: The correct answer is
1 and 3 only. Compact Fluorescent Lamps (CFLs) and Light Emitting Diodes (LEDs) represent two different generations of energy-saving lighting technology, each with distinct physical properties.
- Mechanism of Light Production (Statement 1 is Correct): A CFL works by sending an electric current through a tube containing argon and a small amount of mercury vapour. This generates invisible UV light that excites a phosphor coating on the inside of the tube, which then emits visible light. In contrast, an LED is a solid-state lamp that uses a semi-conductor material. When electricity passes through the diode, it releases energy in the form of photons (light).
- Lifespan (Statement 2 is Incorrect): LEDs are far superior in terms of longevity. An average CFL lasts about 8,000 to 15,000 hours, whereas a high-quality LED lamp can last between 25,000 to 50,000 hours or more. Therefore, the statement that a CFL lasts "much longer" is factually reversed.
- Energy Efficiency (Statement 3 is Correct): LEDs are the most energy-efficient lighting option currently available. They use significantly less wattage to produce the same amount of lumens (brightness) as a CFL. For example, an 8W LED can often replace a 13-15W CFL, resulting in lower electricity consumption.