| SI unit | Watt (W) |
|---|---|
| Relationship | Constant power × time = energy |
| Do not confuse with | Stored energy |
Definition and context
Power indicates how much energy is transferred per unit of time. Its unit is the watt, equivalent to one joule per second. A high power does not in itself imply greater total energy: we need to know how long it operates and how it changes.
In a fictional example, a device that delivers 20 W for ten seconds transfers 200 J if the power remains constant. Another that delivers 10 W for thirty seconds transfers 300 J. The first is more powerful while operating, and the second delivers more energy over the interval selected. When comparing devices, this distinction prevents us from interpreting a power rating as though it were a storage capacity.
What we know and its limits
Introductory reference sheet. Properties and applications depend on measurement conditions; consult the sources before making comparisons.
Follow the evidence
The original sources for exploring this explanation and its limits.
- SI Units
National Institute of Standards and Technology
Base and derived units of the International System.
Image credits
SciClue · AI-generated illustration (OpenAI) · Original source · Recurso editorial de SciClue · generado con IA