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 longer life span than LED lamps. 3. The spectrum o

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Q: (IAS/2021)
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 longer life span 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.

question_subject: 

Science

question_exam: 

IAS

stats: 

0,88,71,39,18,88,14

keywords: 

{'sodium lamps': [0, 0, 0, 1], 'lamps': [0, 0, 1, 5], 'lighting': [0, 0, 0, 1], 'visible light': [0, 0, 6, 6], 'lights': [0, 0, 0, 6], 'light': [16, 4, 34, 62], 'significant colour advantages': [0, 0, 0, 1]}

Option 1 states that Sodium lamps produce light in 360 degrees but it`s not the case with LED lamps. This is accurate since Sodium lamps emit light in a full 360 degrees, whereas LED lamps emit light in a specific direction, reducing the need for reflectors and diffusers that can trap light.

Option 2 suggests that Sodium lamps as street-lights have a longer lifespan than LED lamps. However, this is incorrect, because LED bulbs have a life span of up to 50,000 hours, significantly longer than that of Sodium lamps which typically only last between 12,000-24,000 hours.

Option 3 claims that the spectrum of visible light from Sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street-lighting. This is true as Sodium lamps produce a narrow spectrum of light in the yellow range, making things appear monochromatic yellow or grey, whereas LED lamps produce white light which allows for better color recognition.

So, the correct answer is Option 3, which includes 1 and 3 only. The viability of option 2 is the only difference between Options 3 and 4.