With reference to street-lighting, how do sodium lamps differ from LED lamps?
- 1.Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps.
- 2.As street-lights, sodium lamps have a longer lifespan than LED lamps.
- 3.The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street-lighting.
Select the correct answer using the code given below.
- A.3 only
- B.2 only
- C.1 and 3 only
- D.1, 2 and 3
▶ Answer & Explanation
Correct answer: C. 1 and 3 only
Sodium vapour lamps emit light in all directions, necessitating reflectors to direct light downwards, whereas LED lamps are inherently directional. Sodium lamps produce a distinctive yellow-orange light, which is monochromatic and offers poor colour rendering. In contrast, LED lamps can produce a wide spectrum of colours, providing better visual clarity and colour recognition, which is crucial for identifying objects and people in street lighting. While older sodium lamps might have had comparable or slightly longer lifespans, modern LED technology has significantly advanced in durability and efficiency, often surpassing that of sodium lamps.
Source: UPSC gs1 2021