Voltage Sources vs. Current Sources

Voltage and Current Sources - Comparison and characteristics of voltage sources and current sources in electrical circuits

CharacteristicVoltage SourceCurrent Source
DefinitionMaintains a fixed supply voltage independent of circuit load resistance and applied currentMaintains a fixed supply current independent of circuit load resistance and applied voltage
OutputConstant voltageConstant current
Load DependencyVoltage remains constant regardless of loadCurrent remains constant regardless of load
Ideal ConditionPrefers open circuits (no connection between poles)Prefers closed circuits (short circuits)
Internal ResistanceVery low (ideally zero)Very high (ideally infinite)
Real-world LimitsLimited maximum current and voltageLimited maximum voltage and current

Key Differences

Voltage Source

  • Maintains a fixed supply voltage to an electrical circuit
  • Voltage is independent of the circuit load resistance and the applied current
  • Real voltage and current sources have limits to the voltage/currents they can provide
  • A voltage source "prefer" open circuits (no connection between the poles)

Current Source

  • Maintains a fixed supply current through an electric circuit
  • Current is independent of the circuit load resistance and applied voltage
  • Real voltage and current sources have limits to the voltage/currents they can provide
  • Current sources "prefer" closed circuits (short cuts)