Replacing an incandescent bulb with a fluorescent bulb saves energy.

• A. Not enough information
• B. Depends on bulb type
• C. False
• D. True

Answer: (D)

Energy efficiency in lighting hinges on lumens per watt. Fluorescent bulbs convert electrical energy into visible light more efficiently than incandescent bulbs, so for the same amount of light output, a fluorescent bulb uses far less power. For example, a typical incandescent bulb at about 60 watts can be replaced by a fluorescent option in the teens or low twenties of watts while providing similar brightness. That higher light output per watt means real energy savings over time, especially in fixtures used frequently. There are practical notes—fluorescents may take a moment to reach full brightness, contain mercury, and modern LEDs offer even greater efficiency—but the basic fact remains: replacing an incandescent with a fluorescent bulb generally saves energy.