electricity

Electricity is a form of energy resulting from the presence and movement of electric charges. It includes static electricity, the buildup of charge on objects, and electric current, the continuous flow of charged particles through a conductor. Charge is measured in coulombs, current in amperes, voltage in volts, resistance in ohms, and power in watts. In circuits, energy is transferred when charges move under the influence of a potential difference, described by relationships such as Ohm's law and the power equations P = VI and P = I^2R.

Most electricity is generated by converting energy forms at power plants, then transmitted at high voltage to minimize losses and distributed to consumers. Alternating current (AC) is standard for long-distance transmission because voltages can be easily stepped up and down with transformers; direct current (DC) is used in some modern grids and applications. The electrical grid includes generation, transmission lines, substations, and distribution networks that deliver appropriate voltage levels for homes and industry.

Historically, observations of electrical phenomena date back to ancient times, but systematic study began in the 17th–19th centuries with discoveries by scientists such as Volta, Faraday, and Ohm. The practical development of electric lighting, motors, and communications transformed modern life in the 19th and 20th centuries and continues with ongoing innovations in efficiency, electronics, and renewable energy integration.

Electricity powers devices, lighting, and machinery across nearly all sectors. Safety is a core concern, with risks from shocks, fires, and arc faults, addressed by insulation, grounding, circuit protection, and standards. The environmental impact of electricity depends on how the energy is produced; the shift toward low-emission generation and clean energy technologies aims to reduce emissions and improve reliability and access worldwide.