Parallellstrøm

Parallellstrøm refers to the distribution of electric current in a circuit that contains multiple parallel paths sharing a common voltage source. In a parallel arrangement the potential difference (voltage) across all branches is the same, while the currents through each branch can differ. The total current supplied by the source is the sum of the currents in all branches (I_total = Σ I_i). Kirchhoff's current law underpins this: the current into a node equals the current out.

For components that are purely resistive, the branch current is I_i = V/R_i, where V is the common branch voltage. The equivalent resistance of parallel resistors is given by 1/R_eq = Σ (1/R_i). Consequently, I_total = V/R_eq. Example: two resistors R1 = 6 Ω and R2 = 3 Ω in parallel with a 12 V source. Then I1 = 12/6 = 2 A, I2 = 12/3 = 4 A, I_total = 6 A, and R_eq = 2 Ω.

In AC circuits, or with non-resistive branches, the same parallel relation holds with impedances Z_i: 1/Z_eq = Σ(1/Z_i) and I_i = V/Z_i; the algebra uses complex arithmetic.

Applications: parallel wiring ensures identical voltage across devices, which is common in household circuits; it allows independent operation of devices but makes branch currents dependent on each branch's impedance. Non-ideal sources, wiring resistance, and device tolerances may affect currents and require protective devices sized for the highest expected branch currents.