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Exit to H2 Physics 9478

Internal Resistance Explorer

Explore a real source while discharging or being charged, with a signed-current V–I graph, terminal-p.d. checks, and explicit power accounting.

  • GCE A-Level H2 Physics 2027
Learning goals
  • Apply potential difference, e.m.f. and electrical power relationships.
  • Analyse e.m.f., terminal potential difference and internal resistance in real sources.

Interactive stageLive model

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Change one variable at a time and watch the model respond.

Source setup

Current direction and source values
6.0 V
0.80 Ω
5.0 Ω
Learning options
Guidance

Source checkpoint

Explore the model, then start a prediction.

What to notice:

    Practice run

    Choose a mode and checkpoint count when you want scoring.

    Run mode
    Try Structured Current Practice

    Choose your checkpoint count for guided or challenge mode.

    Study lensDistinguish e.m.f. from terminal potential difference in a real-source model.10 min activity

    Try this

    Define current direction first; the graph then keeps one equation, V = ε − rI.

    Learn to

    • Distinguish e.m.f. from terminal potential difference in a real-source model.
    • Use the correct terminal-p.d. sign for discharging and charging.
    • Interpret the intercept and signed gradient of a terminal-p.d.–current graph.

    Exam transfer

    • Internal resistance
    • Terminal p.d.
    • V–I graph

    Governing idea

    With current defined positive when it leaves the positive terminal, V = ε − rI. During charging I is negative; using charging-current magnitude Icharge gives V = ε + Icharge r.

    Model boundary

    The source has constant e.m.f. and internal resistance, the external load is purely resistive, and wire resistance is negligible. Real values can vary with temperature, state of charge, and current.

    Avoid this trap

    E.m.f. is not always the terminal p.d. During discharge V < ε; during charging V > ε; only at I = 0 does V = ε in this model.

    How to explore

    Connect terminal p.d., lost volts, signed-current graphs, and power balance for a real source.

    Predict the outcome, change one variable at a time, then interpret the result. Completion records participation only and does not award mastery.

    About this activity

    Explore a real source while discharging or being charged, with a signed-current V–I graph, terminal-p.d. checks, and explicit power accounting. A text explanation and no-JavaScript route remain available.

    How this activity affects progress
    Course and syllabus information
    Course
    GCE A-Level H2 Physics
    Edition
    GCE A-Level H2 Physics 2027