- Another common mistake is to confuse energy with power, and this is done even more frequently. It betrays an ignorance of basic physics, and one that, regrettably, is not limited to lay usage. Energy is a scalar, which in physics is a quantity described only by its magnitude; volume, mass, density and time are other ubiquitous scalars. Power measures energy per unit of time and hence it is a rate (in physics, a rate measures change, commonly per time). Establishments that generate electricity are commonly called power plants—but power is simply the rate of energy production or energy use. Power equals energy divided by time: in scientific units, it is watts = joules/seconds. Energy equals power multiplied by time: joules = watts × seconds. If you light a small votive candle in a Roman church, it might burn for 15 hours, converting the chemical energy of wax to heat (thermal energy) and light (electromagnetic energy) with an average power of nearly 40 watts.34 ([Location 641](https://readwise.io/to_kindle?action=open&asin=B08SGC3TD3&location=641)) --- **Tags** -- [[quotes]] **Source** --