Interactive lab · circuits
Circuits: series versus parallel.
Most circuit mistakes come from using the series rule where the parallel rule applies, or forgetting what each wiring shares. This lab animates the current, with flow speed proportional to amps, so you can see how much the wiring changes.
- Model
- series shares I · parallel shares V
- Bench
- live circuit + animated current
- Practice
- 4 problem types · new numbers each time
- Feedback
- names the mistake · e.g. series rule used in parallel
Covers parallel resistance, branch currents, total power for each wiring, and the two RC limits.
- R_eq
- 12 Ω
- I battery
- 0.75 A
- P total
- 6.75 W
- P₁
- 2.25 W
- P₂
- 4.5 W
- parallel would be
- 30.38 W
Series elements share one current; parallel elements share the full voltage. With equal resistors, switching to parallel makes the total power exactly 4× larger, because the battery supplies whatever current the wiring draws.
Predict first then test it
Two identical bulbs and one battery. You can wire the bulbs in series or in parallel. Which wiring makes the pair dissipate more total power — glow brighter overall?
Worked example series or parallel
- 01
Model
A 12 V battery and two identical 6 Ω bulbs. Wire them in series, then in parallel, and compare the total power. Everything follows from one fact: series elements share current, parallel elements share voltage.
Practice desk 0/4 solved
Numeric answers with ±2% tolerance. The wrong paths here are wiring-rule mix-ups — series rules in parallel places, branch vs total, and the two RC limits — and the feedback names which one you used.
A 5 Ω and a 12 Ω resistor are connected in parallel. What is their equivalent resistance?
next Next step
The Atlas entry explains why "just add them" feels right, and the Learn circuits path gives you practice problems.