Voltage source

A voltage source is a two-terminal device which can maintain a fixed voltage. 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 and generators, can be modeled for analysis purposes as a combination of an ideal voltage source and additional combinations of impedance elements.

A voltage source is a two-terminal device which can maintain a fixed voltage. 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 and generators, can be modeled for analysis purposes as a combination of an ideal voltage source and additional combinations of impedance elements. |- align="center" |style="padding: 1em 2em 0;"| |style="padding: 1em 2em 0;"| |- align="center" | Ideal Voltage Source | Ideal Current Source |- align="center" |style="padding: 1em 2em 0;"| |style="padding: 1em 2em 0;"| |- align="center" | Controlled Voltage Source | Controlled Current Source |- align="center" |style="padding: 1em 2em 0;"| |style="padding: 1em 2em 0;"| |- align="center" | Battery of cells | Single cell The internal resistance of an ideal voltage source is zero; it is able to supply or absorb any amount of current. The current through an ideal voltage source is completely determined by the external circuit. When connected to an open circuit, there is zero current and thus zero power. When connected to a load resistance, the current through the source approaches infinity as the load resistance approaches zero (a short circuit). Thus, an ideal voltage source can supply unlimited power. If two ideal independent voltage source are directly connected in parallel, they must have exactly the same voltage; Otherwise, it creates a fallacy in logic, similar to writing down the equation 1=2 . If two ideal independent voltage sources are connected in parallel via a resistor, the source with the lower voltage becomes a consumer. If the source voltages are equal, there is zero current and thus zero power. Voltage sources in parallel shares the burden of current: If an exact duplicate of voltage is connected in parallel to the original one, either one of them will provide half of the electric current that the original voltage source would provide. For the remainder of the circuit, nothing has changed: These two voltage sources together provide the same voltage, and the same current as the original one alone. No real voltage source is ideal; all have a non-zero effective internal resistance, and none can supply unlimited current. However, the internal resistance of a real voltage source is effectively modeled in linear circuit analysis by combining a non-zero resistance in series with an ideal voltage source (a Thévenin equivalent circuit). ==References and notes== ==See also== Dependent source Bandgap voltage reference Voltage divider Voltage reference Voltage regulator

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