By Timothy Banas | Updated March 24, 2022
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Electrical circuits channel power from a source to devices such as light bulbs or speakers. The two primary wiring schemes—series and parallel—each have distinct advantages and trade‑offs in how they handle voltage and current.
Series wiring shares the same current across components; parallel wiring shares the same voltage.
A power source, like a battery, establishes a voltage difference that drives current. In a series configuration, the total voltage equals the sum of each cell. For instance, three 5‑V batteries in series provide 15 V. In contrast, batteries connected in parallel maintain the same voltage (5 V) but double the capacity—so two 5‑V cells can power a circuit for roughly twice as long.
Resistors limit current flow, protecting sensitive components. Series wiring adds resistances: three 2 Ω resistors in series equal 6 Ω. Parallel wiring reduces the overall resistance, calculated as:
\( \frac{1}{R_{\text{tot}}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3} + \dots \)
For example, three 2 Ω resistors in parallel yield a total resistance of approximately 0.67 Ω.
Switches control whether current flows. In a series arrangement, only one open switch interrupts the circuit, which is useful for multi‑location control (e.g., three switches controlling a single light). In parallel, all switches must be open to halt current, but different combinations can redirect flow to various components.
Choosing the right configuration depends on the application—whether you need consistent voltage, current, or redundancy.
