Series vs Parallel: How Circuits Connect

One path or many? It changes everything.

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Series Circuit

Components connected in a single path. Current flows through each one in order. Click a bulb to break it and see what happens to the rest.

All 3 bulbs are on. Click any bulb to break it.

I_total = I_1 = I_2 = I_3 (same current through all)
In series, current has only one path. Break any link and the entire chain stops.
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Parallel Circuit

Components connected in separate branches. Each gets its own path from the battery. Click a bulb to break it. The others keep working.

All 3 bulbs are on. Click any bulb to break it. The others stay lit.

V_total = V_1 = V_2 = V_3 (same voltage across all)
In parallel, each branch gets the full battery voltage. Independent paths mean independent operation.
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Side by Side Comparison

The same three bulbs, wired two different ways. Watch the animated current (yellow dots) flow differently in each configuration.

Series Pros

Simple wiring. Less wire needed. Easy to add a switch that controls everything. Used in: flashlights, holiday light strands (old style).

Parallel Pros

Independent components. One failure does not kill the rest. Each gets full voltage. Used in: house wiring, car electronics, modern everything.

Combined

Real circuits use both. Your house has parallel branches (each room), with series elements within (switch + light in each room).

Fun Fact

Early Christmas lights were wired in series. One burned-out bulb killed the entire string, and you had to test each one to find it. Modern LED strings use parallel wiring, so one dead bulb does not affect the rest.

Circuit Designer!

You've learned the two fundamental ways to connect components. Series shares current, parallel shares voltage. Every circuit ever built uses some combination of both.

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Series: One Path

Components are connected end to end. The same current flows through all. If one breaks, the whole circuit stops. Like old Christmas lights.

Parallel: Many Paths

Components are connected side by side. Each gets the full voltage. If one breaks, the others keep working. Like modern house wiring.

Voltage Divides in Series

In series, the total voltage is split across components. Two equal resistors split a 10V supply into 5V each.

Current Divides in Parallel

In parallel, the total current is split across branches. Each branch gets current based on its resistance. Lower resistance = more current.

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