ELECTRICAL POWER

"The rate at which an electrical source can supply electrical energy. E.g., a battery may be able to store a large amount of energy, but if it has a small power capability it can provide the energy (do some work) only slowly, and it will take a long time to discharge. Another battery with the same energy storage capability but larger power will provide the energy (do work) faster, but will also be discharged faster. Electrical power is expressed usually in units of watt, symbol: ""W"". Unfortunately, the terms ""power"" and ""energy"" are often used interchangeably in everyday language (and sometimes also in the technical literature) even though they are quite distinct concepts, e.g., when we talk about ""energy source"" or ""power source,"" we usually mean the same thing. Not only electrical sources but also loads are characterized by a power rating, e.g., an electrical motor or a light bulb is characterized by the power it needs to operate it. "