College Physics III – Thermodynamics, Electricity, and Magnetism
Definition
Direct current (DC) is a type of electrical current where the flow of electric charge is unidirectional. It contrasts with alternating current (AC), which periodically reverses direction.
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Direct current is used in many low-voltage applications such as batteries, electronics, and solar panels.
In a DC circuit, the voltage remains constant over time.
Ohm's Law ($V = IR$) applies straightforwardly to DC circuits for calculating voltage, current, and resistance.
DC can be converted to AC using an inverter, while AC can be converted to DC using a rectifier.
The first electric power transmission systems used direct current before being replaced by more efficient alternating current systems.
Review Questions
What distinguishes direct current from alternating current in terms of electron flow?
How does Ohm's Law apply differently in DC circuits compared to AC circuits?
What devices are commonly powered by direct current?
Related terms
Alternating Current (AC): A type of electric current where the direction of the flow of electrons switches back and forth at regular intervals or cycles.
Rectifier: An electrical device that converts alternating current (AC) to direct current (DC).
Inverter: A device that converts direct current (DC) into alternating current (AC).