Interactive lab · circuits
Same parts, four times the power.
Most circuit mistakes are one confusion: applying the series rule where the parallel rule belongs, or forgetting which quantity the wiring shares. This bench animates the actual current — flow speed proportional to amps — so you can watch the wiring, not the parts, decide everything.
- Model
- series shares I · parallel shares V
- Bench
- live circuit + animated current
- Practice
- 4 problem types · randomized values
- Feedback
- trap-matched · names the wrong rule
Objectives: parallel equivalence, branch currents, total power by 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. Flip the toggle with equal resistors and the total power jumps by exactly 4× — the battery supplies whatever the wiring demands.
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 same parts, 4× the power
- 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 3 Ω and a 7 Ω resistor are connected in parallel. What is their equivalent resistance?
next Pressure-test the model
The Atlas entry explains why "just add them" feels so right — and the Learn circuits path drills the repair.