Electric power measures how fast a bulb uses energy from electricity. A 60-watt incandescent bulb uses energy eight times faster than an LED that produces the same brightness. When you compare their lux readings, the LED needs roughly one-eighth the power to match the incandescent bulb.

Not all the power a motor consumes does useful work. Some of it fights internal friction, converting energy into heat instead of motion. To measure that loss, you run four DC servomotors — ranging from 30 watts to 100 watts — with no load, measuring the input voltage and current. Then you switch off the power and time how long each motor takes to stop. Bigger motors have larger moving parts, and as the data shows, they lose more energy to friction — because larger moving parts consume power faster, even when the motor isn't doing any work.