Primary General Studies: Energy And Saving Power (Paper 3 (challenge))

Primary General Studies: Energy and Saving Power (Paper 3 (challenge))

2026-11-13

Tutor Prep Guide · Chinese festivals, the lunar calendar, solar terms and leap months

Primary General Studies: Energy and Saving Power (Paper 3 (challenge))

Paper three handles more complex applications: carbon footprint, limits of renewables, wind and water heating, yearly savings for a school and a home, and electric car charging cost.

Direct answers　For percentages, first work out the multiplier: cutting 15 percent means multiplying by 0.85, then by the number of days.

01　Paper details (check answers afterwards)

Item	Detail
Questions	10
Suggested time	20
Difficulty mix	Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1
Chapter	Chapter: Primary General Studies: Energy and Saving Power
Level	parts of a closed circuit, conductors against insulators, series against parallel, adding up battery voltage, and electrical safety

02　Questions (10 items)

FoundationWhat is a carbon footprint?
FoundationWhat is a main limitation of renewable generation?
FoundationWhy is using less usually more effective than generating more?
IntermediateA 2 megawatt wind turbine runs at full output for 24 hours. How many megawatt hours does it produce?
IntermediateA 3000 watt water heater runs for 10 minutes. How many units does it use?
IntermediateA 2000 watt dehumidifier runs for 3 hours. How many units, and what does it cost at $1.2 per unit?
ChallengeForty classrooms each save 1.2 units a day over 200 school days. How many units are saved in total?
ChallengeAt 0.7 kg per unit, how much carbon dioxide do those 9600 units avoid?
ChallengeA household uses 12 units a day and cuts 15 percent. How many units in 365 days?
Error redoA classmate says solar panels generate at night too, so they are very steady. Is that right?

03　Answers and one-line notes

#	Answer	One-line note
1	The total greenhouse gases emitted directly and indirectly by an activity or product.	It is usually given in carbon dioxide equivalent so that different items can be compared.
2	Output rises and falls with the weather and sunlight.	That is why several sources must work together to keep supply steady.
3	Saving cuts emissions at once, costs little and needs no new power station.	The cheapest unit of electricity is the one never used.
4	48 megawatt hours.	2 × 24 = 48 megawatt hours.
5	0.5 units.	3000 × 10 ÷ 60 = 500 watt hours, which is 0.5 units.
6	6 units, costing $7.2.	2000 × 3 = 6000 watt hours, which is 6 units, and 6 × 1.2 = 7.2.
7	9600 units.	40 × 1.2 × 200 = 9600 units.
8	6720 kg, that is 6.72 tonnes.	9600 × 0.7 = 6720 kg.
9	3723 units.	12 × 0.85 = 10.2, and 10.2 × 365 = 3723 units.
10	No. Without sunlight there is no output, so nights need stored or other power.	That is why solar is usually paired with storage or grid backup.

04　What to do after marking

After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
Repeat the same item two days later; move to the next paper only when both attempts are correct.
Parents only need the answer and note columns; there is no need to explain every item.

Paper four clears the conductor, insulator and battery direction misconceptions.Tutor Registration →

Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.