Voltage Source Vs Current Source

Reference data and engineering information about voltage source vs current source for electrical applications.

voltagesourcecurrentsource

Overview

Engineering reference data for Voltage Source Vs Current Source in electrical engineering.

$V = IR$

Voltage = Current × Resistance.

$P = VI = I^2R = V^2/R$

Electrical power.

$E = Pt$

Energy = Power × Time.

Voltage and current sources exhibit distinct behaviors under different load conditions:

Voltage Source: Maintains a constant voltage ( $V = V_s$ ) across its terminals regardless of load. Current is determined by the load resistance ( $I = V_s / R_L$ ). It performs best into an open circuit (infinite $R_L$ ).
Current Source: Maintains a constant current ( $I = I_s$ ) through the load regardless of terminal voltage. Voltage is determined by the load resistance ( $V = I_s \cdot R_L$ ). It performs best into a short circuit ( $R_L = 0$ ).

The power supplied by each source to a load resistance $R_L$ is:

For an ideal voltage source: $P = \frac{V_s^2}{R_L}$

For an ideal current source: $P = I_s^2 \cdot R_L$

Real sources have internal limitations:

Real Voltage Source: Modeled as an ideal voltage source $V_s$ in series with an internal resistance $R_s$ . Terminal voltage drops under load: $V_{terminal} = V_s - I \cdot R_s$ .
Real Current Source: Modeled as an ideal current source $I_s$ in parallel with an internal resistance $R_p$ . Output current diverts through $R_p$ as terminal voltage increases: $I_{load} = I_s \cdot \frac{R_p}{R_p + R_L}$ .

Every real voltage source (Thévenin equivalent) can be converted to a real current source (Norton equivalent) and vice versa:

$V_{\mathrm{Th}} = I_{\mathrm{N}} \cdot R_{\mathrm{Th}}$ $I_{\mathrm{N}} = \frac{V_{\mathrm{Th}}}{R_{\mathrm{Th}}}$

Where $R_{\mathrm{Th}} = R_{\mathrm{N}}$ represents the internal resistance of the source.