A 100A19 lamp has a rated output of 1750 lumens and a life of 750 hours. Its efficiency is?

To determine the efficiency of the A19 lamp, we need to calculate its luminous efficacy, which is expressed in lumens per watt (LPW). The formula to find the luminous efficacy is:

Luminous Efficacy (LPW) = Total Lumens Output / Wattage of the Lamp

In this case, the lamp has a rated output of 1750 lumens. Since it’s a 100A19 lamp, it consumes 100 watts of power. Thus, the calculation would be:

Luminous Efficacy = 1750 lumens / 100 watts = 17.5 LPW

This means that for every watt of power consumed, the lamp produces 17.5 lumens of light output, which provides a measure of the lamp's efficiency. The result makes it clear that option C, 17.5 LPW, correctly indicates the luminous efficacy of the lamp.

Understanding luminous efficacy is essential, as it helps assess the energy efficiency of lighting products. A higher LPW value indicates a more efficient light source, allowing consumers and designers to make informed decisions when selecting lighting solutions.