Series vs Parallel Circuits

The two basic ways to connect more than one component.

In a series circuit, components are connected end-to-end in a single loop — the same current flows through every one of them, and the supply voltage is split across them.

In a parallel circuit, components are connected across the same two points — each one sees the full supply voltage, and the total current is shared between them, adding up as more paths are added.

• Series resistors add directly: R_total = R1 + R2 + R3.
• Parallel resistors combine differently, and the total is always less than the smallest individual value.
• If one bulb fails in a series string, the whole loop breaks; in parallel, the rest keep working.