Q. 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.
[A] 3 only
[B] 2 only
[C] 1 and 3 only
[D] 1, 2 and 3
Answer: C
Notes:
Why thisQuestion) Government focus on LED lights (Ujala Yojana); environment friendly.
Ans) c
Exp) Option c is correct.
Statement 1 is correct.Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps.LED lamps have 180-degree bulb angleto preserve light efficiency and allow for target lighting over areas.
Statement 2 is incorrect.As street lights,sodium lamps have on an average shorter lifespan than LED lamps. High Pressure Sodium lamps tend to have a lifespan averaging 24,000 hours. Whereas, LED lamps lifespan ranges from 25,000 to 200,000 hours.
Statement 3 is correct.The spectrum of visible light from sodium lamps is almostmonochromaticas they areknown for their warm yellow glow. On the other hand, LED lamps offer significant colour advantages in street-lighting. LEDs offer variety of colour options providing better lighting solutions than High Pressure Sodium counterpart.
Source)https://www.homelectrical.com/advantages-led-vs-high-pressure-sodium-area-lights.6.html
Subject) Science
