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
Correct Answer
D
1, 2 and 3
Explanation
Statements 1 and 3 are correct because sodium lamps emit light omnidirectionally (360°) and produce a monochromatic yellow light, whereas LEDs are directional and offer a broad color spectrum for better visibility. Statement 2 is incorrect because LEDs have a significantly longer lifespan (up to 50,000+ hours) compared to high-pressure sodium lamps (around 24,000 hours). The core concept tested is the comparative physical and functional properties of traditional versus modern lighting technologies.
PhysicsSodium Lamps vs. LED Lamps for Street LightingStreet-lightingsodium lampsLED lampslight production360 degreeslife spanvisible light spectrummonochromaticcolour advantages