{"id":304,"date":"2026-06-23T01:49:10","date_gmt":"2026-06-23T01:49:10","guid":{"rendered":"https:\/\/physicsfundamentalsinfo.com\/blog\/?p=304"},"modified":"2026-06-23T02:01:09","modified_gmt":"2026-06-23T02:01:09","slug":"series-parallel-circuits","status":"publish","type":"post","link":"https:\/\/physicsfundamentalsinfo.com\/blog\/electromagnetism\/series-parallel-circuits\/","title":{"rendered":"Series and Parallel Circuits Explained"},"content":{"rendered":"\n
Definition<\/div>

\nSeries and parallel circuits are the two basic ways to connect components in an electrical circuit. In a series circuit, components sit on a single current path, so the same current flows through each one and their voltages add up. In a parallel circuit, components share the same voltage across separate branches, and their currents add up.\n<\/p><\/div>\n\n

Flip one switch in your house and the other lights stay on. Pull a single bulb from an old string of fairy lights and the whole strand goes dark. Same electricity, completely different behaviour \u2014 and the only thing that changed is how the parts are wired together<\/em>.<\/p>\n\n

That wiring choice sits at the heart of every circuit you will ever build or fix. Get it right and you can share a voltage, limit a current, or keep devices independent. Get it wrong and nothing lights up. This guide shows exactly how each arrangement behaves, with original diagrams, formulas, and eight worked examples.<\/p>\n\n

What Are Series and Parallel Circuits?<\/h2>\n\n

Picture a single-lane road next to a motorway with several lanes. On the single lane, every car follows the one in front \u2014 that is a series circuit<\/strong>. On the motorway, traffic spreads across lanes and travels side by side \u2014 that is a parallel circuit<\/strong>.<\/p>\n\n

More precisely, a series circuit connects components end to end in one continuous loop, leaving a single path for current. A parallel circuit connects components across the same two points, giving the current two or more separate branches to flow through.<\/p>\n\n

This one structural choice decides three things at once: how the current splits, how the voltage divides, and what happens when a component fails. Everything else below follows from those three rules.<\/p>\n\n\n <\/rect>\n <\/line>\n\n Series circuit<\/text>\n One path \u2014 current is the same everywhere<\/text>\n\n <\/line>\n <\/line>\n <\/line>\n <\/line>\n <\/line>\n\n <\/line>\n <\/line>\n +<\/text>\n\n <\/rect>\n R\u2081<\/text>\n <\/rect>\n R\u2082<\/text>\n <\/rect>\n R\u2083<\/text>\n\n <\/polygon>\n current I (one loop)<\/text>\n\n Parallel circuit<\/text>\n Many paths \u2014 voltage is the same across each<\/text>\n\n <\/line>\n <\/line>\n <\/line>\n <\/line>\n +<\/text>\n\n <\/line>\n <\/line>\n\n <\/line>\n <\/rect>\n <\/line>\n R\u2081<\/text>\n\n <\/line>\n <\/rect>\n <\/line>\n R\u2082<\/text>\n\n <\/line>\n <\/rect>\n <\/line>\n R\u2083<\/text>\n\n current splits: I = I\u2081 + I\u2082 + I\u2083<\/text>\n<\/svg>\n

Figure 1: The same three resistors wired in series (one loop) and in parallel (three branches).<\/p>\n\n

The single rule that defines each<\/h3>\n\n

In a series<\/strong> circuit there is only one path, so the current has nowhere else to go \u2014 it is identical through every component. In a parallel<\/strong> circuit every branch connects to the same two nodes, so each branch feels the same voltage.<\/p>\n\n

Hold onto one line and the rest is bookkeeping: series shares current, parallel shares voltage<\/em>. The two cases are mirror images \u2014 voltage and current simply swap roles<\/a> between them.<\/p>\n\n

The Series and Parallel Circuit Formulas<\/h2>\n\n

All of the maths rests on a single relationship \u2014 Ohm’s law<\/a> \u2014 which ties voltage, current, and resistance together.<\/p>\n\n

V = I \u00d7 R<\/div>\n\n