Direct current

Direct current (DC or "continuous current") is considered as the constant flow of electrons in the single direction from low to high potential. This is typically in a conductor such as a wire, but can also be through semiconductors, insulators, or even through a vacuum as in electron or ion beams. In direct current, the electric charges flow in the same direction, distinguishing it from alternating current (AC). A term formerly used for direct current was Galvanic current.

Types of direct current

Long after the usage of this term had been established, physicists realized that electrons actually flow to a negative potential (pole) and so-called "holes" flow to the opposite one. But the first usage of the term was not changed.

The first commercial electric power transmission that was developed by Thomas Edison in the late nineteenth century used direct current. Because of the advantage of alternating current over direct current in transforming and transmission, electric power distribution today is nearly all alternating current. For applications requiring direct current alternating current is distributed to a substation to convert the power to direct current.

See also

• Electric current
• Alternating current
• London Underground

Other websites

• "AC/DC: What's the Difference?". Edison's Miracle of Light, American Experience. (PBS)

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