E.m.f. and p.d.: energy per charge sim
Drag 1.5 V cells into a four-bay battery holder, flip one round and see it subtract, move a voltmeter's plugs across one cell or the whole battery, and watch energy-per-coulomb bars show each coulomb gaining E joules in the cells and giving it all up in two lamps; then work out the total e.m.f., the energy given to 2 C and the p.d. across the second lamp yourself.
Electric circuits: e.m.f. and p.d. as energy per unit charge · covers the O-Level, IGCSE, GCSE topic
What the sim shows
Model. Every p.d. and current comes from one nodal-analysis solver shared by the circuit figures. Each cell 1.5 V; ideal by default, or 0.5 Ω internal resistance each when turned on (chosen, beyond the syllabus). A dummy cell is a spacer that conducts and has no e.m.f. Lamps 2.5 V 0.3 A and 3.5 V 0.3 A, filament resistance rising with p.d. (a chosen simple law). Voltmeters ideal (no current), 20 V range reading to 0.01 V; a minus sign means the red plug is at the lower potential. Leads, contacts and the switch are perfect conductors. Steady d.c.: the cells never run down.
- The cell or plug you are moving (choose another with 1–6)
- Battery holder, tray of spare and dummy cells, voltmeters VB, V1, V2, switch, two lamps
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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