9478 / 2027

Chapter 16

Circuits

Identify the nodes, the measured component and the source model before choosing a circuit equation.

Use physical connections and stated operating conditions to explain measurements and predict useful circuit outputs.

Circuit symbols, resistance and material behaviour, sources and resistor networks, potential dividers, capacitor combinations, RC processes and discharge-data analysis. For 9478 (2027).

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  1. Read connections and place meters

    Recognise component symbols, preserve node pairs in a redrawing and choose the correct measurement endpoints.

  2. Resistance, material and geometry

    Use matched voltage/current readings, wire dimensions and a reciprocal area graph to distinguish resistance from resistivity.

  3. I-V curves and temperature

    Read four component characteristics and explain typical metal and NTC behaviour using drift and carrier density.

  4. Sources with internal resistance

    Distinguish e.m.f., terminal p.d. and internal loss, and interpret voltage and output-power graphs.

  5. Reduce a network and work back

    Derive series and parallel rules, recover branch values and explain how opening one branch changes the complete circuit.

  6. Potential dividers and sensors

    Select the correct output arm, use potentiometer and sensor responses, and account for a parallel output load.

  7. Capacitor combinations

    Use equal-voltage and isolated-node charge constraints in parallel, series and mixed capacitor arrangements.

  8. RC charging and discharging

    Trace the switching paths and use consistent current, charge and voltage references in both exponential processes.

  9. Infer a time constant from data

    Use a dimensionless log plot, numerical current area and loading analysis to interpret a discharge record.