Combining resistors sim
Drag real resistors into the clips of a resistance board to wire them in series or in parallel, measure V and I with real digital meters, work out R = V ÷ I from your own readings and check it against the series and parallel formulas, and see that adding a parallel branch lowers the total while adding in series raises it.
Practical electricity and resistance: combining resistors · covers the O-Level, IGCSE, GCSE topic
What the sim shows
Model. Every current and p.d. comes from one nodal-analysis solver shared by the circuit figures. Supply: 0 to 6 V in 0.5 V steps, internal resistance 0.5 Ω (chosen). Each lead 0.01 Ω; the board's bars and clips are taken as perfect conductors. Resistors rated 1 W, marked ±5 %; each true value is drawn evenly within ±5 % of its marking by a seeded generator, a new batch on each load (chosen). Digital ammeter: 200 mA range (reads to 0.0001 A, 1 Ω, 200 mA fuse) and 2 A range (reads to 0.001 A, 0.1 Ω); digital voltmeter 20 V range (reads to 0.01 V, 10 MΩ); chosen typical values. The voltmeter's red lead is on P0, after the ammeter, so the ammeter's resistance is not in V; the voltmeter's own tiny current (under 0.002 % of the total with these resistors) is in I. Steady d.c.: the resistors do not warm up, and their values do not drift.
- The resistor or plug you are moving (pick another with 1–5)
- Power supply, switch, ammeter, voltmeter, resistance board with clips, a rack of resistors
Use it in your lessons
- Try it here: anyone can unlock 2 figures free, and a free account unlocks up to 5. Runs on a laptop, a Chromebook or a phone; nothing to install.
- Present it and share student links with the teacher plan, from US$5 a month, billed yearly.
- Put it on your own website or LMS for US$9, paid once, or every sim from US$29 a month.
Free guide: 12 practicals as sims, and how to run one in a lesson →
Need a version for your exact set-up? Have one made: US$49 a figure in an order of 5.
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