Mission EC3 Voltage, Power and Energy
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Mathematically, power is a rate quantity - a time-based quantity. It is the rate at which a force does work upon a charge. Power (P) is calculated from knowledge of the work done (W) and the time (t) required to do this work. The formula is
P = W / t.
It is often the case that the units of a quantity can be determined from the formula for the quantity. In the case of work, the units would be a unit of force multiplied by a unit of displacement. This would be a Newton • meter, abbreviated N•m. The unit Joule, abbreviated J, is defined to be equivalent to a N•m. Thus, Joule is the standard unit of work in the metric system.
In the case of power, the units would be a unit of work divided by a unit of time. This would be a Joule/second, abbreviated J/s. The unit Joule/second is defined to be equivalent to a Watt. Thus, Watt is the standard unit of power in the metric system.
