Multiple choice

Sodium vapour lamps are preferred to incandescent lamp because of

  1. Higher tolerance to voltage fluctuation

  2. Higher intensity of illumination

  3. Easy installation

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sodium vapor lamps produce nearly monochromatic yellow light (589 nm) with very high luminous efficacy - around 100-200 lumens per watt compared to 10-20 lumens per watt for incandescent lamps. This gives them much higher intensity of illumination for the same power consumption.

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