Direct current

Direct current (DC) is electric charge flow that maintains the same direction, though its magnitude may vary over time. It contrasts with alternating current, whose direction reverses periodically.

Electric current: Electric current is the rate at which electric charge passes through a surface. Direct current is the directionally steady form of this broader quantity.
Electric circuit: An electric circuit is an interconnected path through which electric current can flow. Direct current is analyzed as flow through a connected circuit.
Battery: A battery converts chemical energy into electrical energy through electrochemical reactions. Batteries are common sources of direct current for standalone devices.
Alternating current: Alternating current periodically reverses direction, often while its magnitude also changes. Its reversing direction is the defining contrast with direct current.
Voltaic pile: The voltaic pile was an early battery made from alternating metal discs and electrolyte-soaked separators. Volta's device supplied continuous unidirectional current in the early nineteenth century.
Electric charge: Electric charge is a fundamental property of matter that produces and responds to electromagnetic forces. Its motion through a conductor constitutes direct current.
Electromotive force: Electromotive force is energy supplied per unit charge by a source, measured in volts. It describes how a battery or generator can maintain charge separation.
Solar cell: A solar cell converts light into electrical energy using the photovoltaic effect. Photovoltaic cells produce DC that usually needs conditioning for practical use.
Pulsating direct current: Pulsating direct current flows in one direction while its magnitude varies periodically or irregularly. It remains direct current even when rectification leaves substantial ripple.
Alessandro Volta: Alessandro Volta was an Italian physicist who developed the voltaic pile. His battery made sustained direct current available for controlled experiments.

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