Series Circuits
Components in series share one path.
About this topic
In a series circuit the components are connected end to end in a single loop. The same current flows through each, the voltages across components add up to the supply voltage, and the total resistance is the sum: R = R₁ + R₂ + ….
If one component fails, the circuit breaks and all stop, like old-style fairy lights. Adding more resistors reduces current. For instance, a 6 V battery with a 2 ohm and a 4 ohm resistor in series has total resistance 6 ohms and current 1 A; the voltages across the resistors are 2 V and 4 V, adding to 6 V.
Series arrangements are used in fuses, switches and for dividing voltage, as in a potential divider that supplies a sensor circuit. Batteries in series add their voltages, which is why a torch uses several cells end to end.
A typical error is to think the current is smaller after passing through the first resistor. It is the same everywhere in the loop; what changes is the voltage, shared out in proportion to each resistance.
Key ideas
- Same current everywhere
- Voltages add
- R_total = R₁ + R₂
Quick check
Use cases: where Series Circuits helps
- Homework: review the key idea behind Series Circuits before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Series Circuits without notes.
- Visual learning: play with the interactive lab to see how Series Circuits changes when you adjust its inputs.
- Teaching a friend: explain Series Circuits in your own words, then compare your version with the key ideas.
The same laws describe car crashes, sports, satellites and everyday machines.
Frequently asked questions
What is Series Circuits?
Components in series share one path.
What will I learn in Series Circuits?
Same current everywhere. Voltages add. R_total = R₁ + R₂.
Is Series Circuits part of Physics?
Yes. It is one of 150 Physics topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Series Circuits lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Series Circuits?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.