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Simple Definitions

The most important electronics terms, demystified in one place.

Voltage source

Our Take

A voltage source is a power source that provides a set voltage no matter how much current is required to maintain that voltage level. An ideal voltage source can source infinite current but obviously that isn’t the case in reality. Voltage sources are the most common power sources in normal life and even in electrical engineering. Do not short-circuit voltage sources.

Book Definition

Supplies potential difference across two terminals. Has internal series ri.


A voltage source is a two-terminal device which can maintain a fixed voltage.[1] An ideal voltage source can maintain the fixed voltage independent of the load resistance or the output current. However, a real-world voltage source cannot supply unlimited current. A voltage source is the dual of a current source. Real-world sources of electrical energy, such as batteries, generators, can be modeled for analysis purposes as a combination of an ideal voltage source and additional combinations of impedance elements.

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