Question

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 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.  

1. 3 only
2. 2 only
3. 1 and 3 only
4. 1, 2 and 3

Answer 1

Correct Answer - Option 3 : 1 and 3 only

The correct answer is 1 and 3 only.

• Difference Between Sodium Vapor and LED Lights
  • Sodium lamps are omnidirectional in that they emit light at 360 degrees, while led lamps emit light at 180. Hence, Statement 1 is correct.
  • The two different technologies are entirely different methods of producing light.
  • LED lifespan can be greater than 100,000 hours, more than four times that of sodium lamps. Therefore, the Lifespan of LED is more than Sodium. Hence, Statement 2 is incorrect.
  • Sodium vapor bulbs contain metals that are evaporated into inert gas within the glass casing while LEDs are a solid-state technology.
  • Both technologies are very efficient.
  • The difference is that sodium vapor lights were the most efficient technology of the 1970s while LEDs are the modern-day equivalent.
  • Sodium lamps are monochromatic, and LEDs can be designed to generate the entire spectrum of visible light colors without having to use the traditional color filters required by traditional lighting. Hence, Statement 3 is correct.
  • Although sodium vapor lighting beats virtually every other technology in terms of energy efficiency (which is why it was chosen to illuminate the streets of so many cities), it loses out to LEDs.
  • Both LEDs and sodium vapor lights emit electromagnetic radiation across a small portion of the visible light spectrum, however, LEDs waste much less energy producing waste heat and they also provide an incredibly better variety of high color rendering index options to the user (thus eliminating the monochromatic black appearance of objects illuminated by LPS and HPS bulbs).