LuduminaMG-05 · MG-U2 · Planned
Electric motors
Learning objectives
Explain coil rotation through forces on opposite sides; connect electrical work to mechanical output.
8463 §§4.7.2.3 / 8464 §§6.7.2.3
DfE single-science pp.41–42 / Combined pp.34–35. Evidence checked 30 September–1 October 2026. Skills: WS1.2,1.4,3.6.
Needs firstMG-04
Explanation
Forces on opposite sides of a current-carrying coil form a turning effect. The motor converts electrical work into mechanical output with some dissipation. A simple continuous DC motor reverses the relevant coil current as it turns so the turning effect continues.
Concepts, equations and units: Motor-effect forces and moments; N and N m qualitatively; split-ring role can support explanation but no extra motor design equations.
Prediction, demonstration and game exercise
Predict, observe, explain
Freeze a coil at several orientations and label opposite forces; show reversal for continuing rotation.
Planned learner game exercise
Repair coil polarity/contacts in a model motor then predict rotation on field reversal.
Independent practice
Annotated motor diagram and energy-transfer explanation.
Original practice example · Shared Higher
Why can a current-carrying coil rotate even though forces on opposite sides point oppositely?
Show working and model answer
Working / reasoning
The forces act on different sides of the pivot, so their moments can act in the same rotational direction.
Answer
Opposite forces form a turning effect on the coil rather than simply cancelling rotation.
Exit check and success criteria
Opposite-side forces give consistent turning direction and energy accounting includes surroundings.
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
Both sides feel the same-direction force; a motor creates energy; every motor turns continuously without commutation.
Practical preparation
Optional safe model motor demonstration; no RP.
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.