UPSC 2021 - Question 72

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 cast 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