Electrical power

Electrical power is the rate at which an electrical circuit transfers or converts energy. It is measured in watts and depends on voltage and current.

Electric current: The rate at which electric charge passes a point in a circuit. Current combines with voltage to determine the rate of electrical energy transfer.
Electric charge: A fundamental property of matter that causes electric forces and is measured in coulombs. Current is charge flow, the moving quantity whose energy transfer power measures.
Electric power system: A network that generates, transmits, and distributes electricity to users. Its equipment is rated and operated according to electrical power flows.
Electrical energy: Energy transferred or stored through electrical interactions, commonly measured in joules or kilowatt-hours. Energy accumulates over time; power describes the rate of that transfer.
Voltage: The electric potential difference between two points, equal to energy transferred per unit charge. Voltage sets the energy available per unit charge moving through a circuit.
Energy: A physical quantity that measures the capacity of a system to cause change or perform work. Electrical power is energy transfer per unit time, not energy itself.
Electric motor: A device that converts electrical energy into mechanical motion. Its electrical input power is compared with mechanical output to measure efficiency.
Apparent power: The product of RMS voltage and RMS current in an AC circuit, measured in volt-amperes. It differs from real power when voltage and current are out of phase.
Ohm's law: The relation stating that current through a conductor is proportional to voltage across it when temperature and other conditions are fixed. Combining this relation with power gives formulas based on resistance.
Watt: The SI unit of power, equal to one joule per second. Electrical power is commonly reported in watts and multiples such as kilowatts.

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