Chapter 9
Circuits
Identify the nodes, the measured component and the source model before choosing a circuit equation.
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Read connections and place meters
Recognise component symbols, preserve node pairs in a redrawing and choose the correct measurement endpoints.
Resistance, material and geometry
Use matched voltage/current readings, wire dimensions and a reciprocal area graph to distinguish resistance from resistivity.
I-V curves and temperature
Read four component characteristics and explain typical metal and NTC behaviour using drift and carrier density.
Sources with internal resistance
Distinguish e.m.f., terminal p.d. and internal loss, and interpret voltage and output-power graphs.
Reduce a network and work back
Derive series and parallel rules, recover branch values and explain how opening one branch changes the complete circuit.
Potential dividers and sensors
Select the correct output arm, use potentiometer and sensor responses, and account for a parallel output load.