LuduminaEL-04 · EL-U1 · Planned
Component characteristics and I–V investigation
Learning objectives
Compare resistor, lamp and diode I–V characteristics; explain temperature dependence; describe LDR/thermistor responses.
8463 §§4.2.1.4 / 8464 §§6.2.1.4
DfE single-science pp.39–41 / Combined pp.33–34. Evidence checked 30 September–1 October 2026. Skills: WS2.2–2.7,3.5; MS4c,4d,4e.
Explanation
An ohmic resistor has a straight I–V relation at constant temperature. A filament lamp warms as current increases, increasing resistance. A diode conducts mainly in one direction. Thermistor and LDR resistance responds to temperature and light respectively.
Concepts, equations and units: Ohmic resistor at constant temperature; lamp resistance rises with temperature; diode direction; thermistor R falls as temperature rises, LDR R falls as light rises.
Prediction, demonstration and game exercise
Predict, observe, explain
Sweep positive/negative p.d. safely in a model; compare three graphs and explain nonlinear lamp heating.
Planned learner game exercise
Build each circuit; choose p.d. steps and repeats; add separate temperature/light sensor demonstrations.
Independent practice
Plot three I–V graphs, calculate resistance at stated operating points and choose a sensor application.
Original practice example · Shared
A lamp has 3 V across it and current 0.25 A at one operating point. Find its resistance there.
Show working and model answer
Working / reasoning
R = 3/0.25; this does not imply constant R at other voltages.
Answer
12 Ω at that operating point.
Exit check and success criteria
All graph types identified, diode direction correct and one heating/control limitation explained.
During practice, compare the prediction with evidence and give an error-specific prompt. The exit item uses a fresh context or fresh values, answered independently.
Misconceptions, practical links and mastery
Check these misconceptions
Lamp obeys constant R; diode has identical resistance in either direction; sensors create charge.
Practical preparation
RP-P4/RP-C16: resistor, filament lamp and diode. LDR/thermistor demonstrations supplement the RP. AT6,7.
Virtual preparation and revision only. Required hands-on activities and school records remain separate.
Proposed mastery
0: not yet evidenced. 1: supported. 2: independent exit criteria met. 3: successful changed-context transfer. Advance at 2; revisit with fresh retrieval. These are not GCSE grades.