LuduminaEL-09 · EL-U3 · Planned
The National Grid
Learning objectives
Explain Grid structure and qualitative roles of step-up/down transformers; connect high p.d. to reduced transfer losses.
8463 §§4.2.4.3 / 8464 §§6.2.4.3
DfE single-science pp.39–41 / Combined pp.33–34. Evidence checked 30 September–1 October 2026. Skills: WS1.4,3.6; MS3c.
Explanation
The Grid links generators and consumers through cables and transformers. At the same transmitted power, higher p.d. permits lower current, reducing cable heating. Quantitative transformer ratios are a separate Physics Higher branch, while the qualitative Grid role is shared.
Concepts, equations and units: Grid: cables and transformers; high V enables lower I for same P; cable heating linked to I²R qualitatively; numerical transformer ratios reserved MG-09 P-H.
Prediction, demonstration and game exercise
Predict, observe, explain
Compare model transmission routes for fixed delivered power; distinguish distribution from energy resource.
Planned learner game exercise
Choose transformer locations and transmission p.d.; complete a system transfer map.
Independent practice
Calculate two cable powers using supplied I,R and give a three-link explanation.
Original practice example · Shared
Compare cable losses at 10 A and 5 A through the same 2 Ω cable.
Show working and model answer
Working / reasoning
P_loss = I²R: 10² × 2 = 200 W; 5² × 2 = 50 W.
Answer
200 W versus 50 W; halving current quarters loss.
Exit check and success criteria
Correct topology and high V → lower I → less heating explanation; no claim transformers create energy.
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
High voltage means more power automatically; every transformer topic is Combined Higher content.
Practical preparation
No RP; optional safe transformer demonstration by teacher.
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.