MYP Physics · 14 · extended response
Move power from a hill turbine to a village
Magnetism and electromagnetism · Original GioPhysics question with a detailed, mark-by-mark answer guide.
- Demand
- discriminating
- Marks
- 8
- Topics
- 2
- Answer
- Complete
A small hydro generator is 4 km from a village. Engineers can transmit 60 kW at either 600 V or 6.0 kV through the same cables. Transformers would be needed at both ends of the higher-voltage option.
- a
Calculate Calculate the transmission current for each voltage, assuming the same 60 kW power.
2 marks - b
Explain Explain why the higher-voltage option reduces heating in the same cables.
3 marks - c
Evaluate Recommend an option, considering physics, infrastructure, safety, and community needs.
3 marks
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a
Calculate Calculate the transmission current for each voltage, assuming the same 60 kW power.
Build a chain of claim, evidence and physics reasoning. Address more than one relevant factor, identify a limitation or assumption, and finish with a conclusion that is conditional on the evidence rather than absolute.
- 1
Calculates 60 000 W ÷ 600 V = 100 A.
- 2
Calculates 60 000 W ÷ 6000 V = 10 A.
b
Explain Explain why the higher-voltage option reduces heating in the same cables.
Build a chain of claim, evidence and physics reasoning. Address more than one relevant factor, identify a limitation or assumption, and finish with a conclusion that is conditional on the evidence rather than absolute.
- 1
Uses cable heating power P = I²R or equivalent reasoning.
- 2
States that the current is reduced by a factor of 10.
- 3
Concludes that resistive heating is reduced by a factor of 100 for the same cable resistance.
c
Evaluate Recommend an option, considering physics, infrastructure, safety, and community needs.
Build a chain of claim, evidence and physics reasoning. Address more than one relevant factor, identify a limitation or assumption, and finish with a conclusion that is conditional on the evidence rather than absolute.
- 1
Uses lower transmission loss as evidence for the 6.0 kV option.
- 2
Considers a relevant trade-off such as transformer cost, maintenance skills, insulation, or high-voltage safety.
- 3
Gives a justified recommendation conditional on reliable protection, training, and lifecycle cost.
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