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Build a series, parallel or combination circuit, set the EMF and each resistor value, and watch the current flow through the schematic while the total resistance, current, and each resistor’s voltage and power update live — with the rule (R = ΣRᵢ or 1/R = Σ1/Rᵢ) shown beside every answer. It makes the core idea concrete: same current in series, same voltage in parallel, all tied together by Ohm’s law V = I·R. Resistors glow brighter as they dissipate more power.
| Resistor | R (Ω) | I (A) | V (V) | P (W) |
|---|---|---|---|---|
| R1 | 10 | 0.40 | 4.0 | 1.60 |
| R2 | 10 | 0.40 | 4.0 | 1.60 |
| R3 | 10 | 0.40 | 4.0 | 1.60 |
Model: Ohm’s law V = I·R with an ideal EMF source (optional internal resistance). Supports series, parallel and simple combination networks (CAIE 0625 §4.2–4.3 / IB B.5); free-form breadboard and bridge/mesh circuits are out of scope. Values are computed in full precision and rounded for display. Educational tool — a guide for understanding, not a substitute for exam practice.
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Last updated: July 2026
The rules, Ohm’s law, and what this tool covers.
In a series circuit the components are joined end to end in a single loop, so the same current flows through every component and the source voltage is shared between them. In a parallel circuit the components are on separate branches, so each branch has the full source voltage across it while the current splits between the branches. The simulator lets you switch between the two and see the currents and voltages change instantly.
In series you simply add the resistances: R_total = R₁ + R₂ + R₃ + … . In parallel you add the reciprocals: 1/R_total = 1/R₁ + 1/R₂ + 1/R₃ + … , then take the reciprocal of the result. A key consequence is that the total resistance of a parallel combination is always smaller than the smallest single resistor, because you have added extra paths for the current.
Ohm’s law states V = I·R — the potential difference across a component equals the current through it multiplied by its resistance. The simulator applies it everywhere: it finds the total resistance for your chosen arrangement, uses I = EMF ⁄ R_total for the current from the source, then works out each resistor’s own current, voltage (Vᵢ = Iᵢ·Rᵢ) and power (Pᵢ = Iᵢ·Vᵢ). Brighter resistors are dissipating more power.
Each parallel branch gives the current an additional path to flow through. More paths means it is easier — overall — for charge to move, so the combined resistance falls. Numerically, every extra 1/Rᵢ term you add to 1/R_total makes the sum larger, and a larger 1/R_total means a smaller R_total. It is one of the most common exam misconceptions, which is exactly why seeing it happen live helps.
It covers the series, parallel and simple combination (one resistor in series with a parallel group) networks that make up the Cambridge IGCSE 0625 and IB B.5 core — the arrangements that can be solved exactly with the series and parallel rules. Free-form breadboard layouts and bridge or mesh networks that need simultaneous-equation (nodal) analysis are deliberately out of scope, the same way this tool keeps internal resistance as an optional “beyond IGCSE” extra rather than the default.
Circuit problems reward a clear routine — redraw the circuit, decide what is in series and what is in parallel, reduce it step by step, then apply Ohm’s law. A GetYourTutors physics specialist who comes to your home in Dubai can work through past-paper circuit questions with your child, fix the common series-versus-parallel mix-ups, and build the confidence to handle combination circuits under exam conditions.