THE TRANSFORMER
3 marks · NormalDescribe two reasons why thick, insulated copper wire and a plastic-coated soft iron core are used in transformer construction.
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Also accept: Thick copper wire reduces resistance (minimises heating losses in coils); insulation prevents short-circuiting between coil wires; plastic coating on iron core prevents energy loss by eddy currents.
Common mistakes: Only mentioning copper for conductivity without addressing losses; Not specifying insulation purpose
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Marking points
B1 · 1 mark · States thick copper wire decreases resistance and reduces heating losses.
B2 · 1 mark · States insulation prevents short circuits between coil wires.
B3 · 1 mark · States plastic coating on iron core prevents eddy current losses.
Worked solution
Thick copper wire reduces electrical resistance, so less energy is lost as heat in the coils. The insulation around each coil wire prevents short circuits between turns. A plastic-coated soft iron core reduces formation of eddy currents in the core, which minimises energy lost as heat due to magnetic effects.