Lightbulb efficiency

Lightbulb efficiency

• A. The longest rated life
• B. The bulb with the lowest heat emission
• C. The one that gives off the least heat
• D. The brightest output

Answer: (C)

Efficiency of a lightbulb is about how well electrical energy is turned into visible light, with any energy not used for light showing up as heat. Heat represents energy wasted, so a bulb that gives off the least heat for a given amount of light is the best indicator of efficiency—it means more of the energy is becoming light rather than heat. The other traits, like a long rated life or very bright output, don’t by themselves prove efficiency because they can occur with different energy use; a bulb can be bright but still waste a lot of energy as heat, or last long but be inefficient.

Efficiency of a lightbulb is about how well electrical energy is turned into visible light, with any energy not used for light showing up as heat. Heat represents energy wasted, so a bulb that gives off the least heat for a given amount of light is the best indicator of efficiency—it means more of the energy is becoming light rather than heat. The other traits, like a long rated life or very bright output, don’t by themselves prove efficiency because they can occur with different energy use; a bulb can be bright but still waste a lot of energy as heat, or last long but be inefficient.