IGCSE Physics Energy Resources Questions and Worked Solutions (1.7.3) | 0625

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IGCSE Physics 0625 · Topic 1.7.3

IGCSE Physics Energy Resources Questions and Worked Solutions

50 topic-wise practice questions on Energy Resources (Unit 1: Motion, Forces and Energy), written to the Cambridge IGCSE Physics 0625 syllabus for 2026–2028, each with a step-by-step worked solution.

50 questions24 Core16 Extended10 Challenge122 marksTextbook §1.7 · pp. 60–77
Questions tagged Core are for all candidates (Papers 1 & 3). Questions tagged Extended are Supplement content (Papers 2 & 4). Questions 41–50 are harder Challenge questions. Try each question first, then tap Show solution to check your working.

Topic guide: Energy Resources

Electricity is generated from many energy resources, each with advantages and disadvantages. Efficiency measures how much of the input energy is usefully transferred.

Key formulas

efficiency = (useful energy output ÷ total energy input) × 100%energy formExtended
efficiency = (useful power output ÷ total power input) × 100%power formExtended

Prerequisite knowledge

  • Energy stores and conservation (1.7.1)
  • Power (1.7.4) for the power form of efficiency
  • Percentages

Exam tips & common mistakes

  • Give a specific advantage AND disadvantage — 'it is good' scores nothing
  • Efficiency can never exceed 100%
  • Wasted energy = input − useful output

Key facts from the syllabus (1.7.3)

  • Resources: chemical (fossil fuels, biofuels), hydroelectric, tidal, wave, wind, geothermal, nuclear fission, solar cells and solar panels
  • Compare resources by renewability, availability, reliability, scale and environmental impact
  • Fossil fuels release CO₂; nuclear produces radioactive waste; renewables can be weather-dependent
  • Solar cells produce electricity; solar panels heat water
  • Extended the Sun is the source of most resources except geothermal, nuclear and tidal
  • Extended the Sun's energy comes from nuclear fusion; research into fusion power stations aims to generate electricity on a large scale

Textbook: §1.7 Energy, work and power, pp. 60–77

1
Core[3 marks]

Describe how electricity is generated in a fossil-fuel power station.

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Method: Chemical → thermal → kinetic → electrical.

Fuel burned to heat water in a boiler → steam turns a turbine → turbine turns a generator
2
Core[2 marks]

State one advantage and one disadvantage of using fossil fuels.

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Method: Reliable but polluting/non-renewable.

Advantage: reliable, large scale. Disadvantage: non-renewable, produces CO₂ (and other pollution)
3
Core[2 marks]

Explain why biofuels are described as renewable.

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Method: Can be regrown.

They come from plants that can be regrown in a short time
4
Core[3 marks]

Describe how a hydroelectric dam generates electricity.

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Method: Gravitational potential → kinetic → electrical.

Water stored high behind the dam flows down through turbines, which drive generators
5
Core[2 marks]

State two disadvantages of hydroelectric power.

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Method: Environmental impact.

Floods valleys/habitats; only possible in suitable (hilly, wet) locations; high build cost
6
Core[2 marks]

Describe how tidal energy is used to generate electricity.

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Method: Barrage traps water at high tide.

A barrage traps water at high tide; it flows out through turbines that drive generators
7
Core[2 marks]

State one advantage and one disadvantage of wave power.

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Method: Renewable, but unreliable.

Advantage: renewable, no fuel cost. Disadvantage: unreliable (depends on weather), small scale
8
Core[2 marks]

Describe how geothermal energy generates electricity.

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Method: Hot rocks heat water.

Water is pumped down to hot rocks, returns as steam which turns turbines and generators
9
Core[2 marks]

State one advantage and one disadvantage of nuclear power.

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Method: No CO₂, but radioactive waste.

Advantage: no CO₂, reliable, large scale. Disadvantage: radioactive waste, risk of accidents
10
Core[2 marks]

Distinguish between solar cells and solar panels.

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Method: Cells → electricity; panels → heat water.

Solar cells convert light to electricity; solar panels absorb infrared to heat water
11
Core[2 marks]

State the original source of wind energy.

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Method: Sun heats air unevenly.

The Sun (uneven heating of the Earth's surface causes winds)
12
Core[1 mark]

Describe what is meant by efficiency.

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Method: Fraction of energy usefully transferred.

The proportion of input energy transferred to useful output
13
Core[2 marks]

Classify as renewable or non-renewable: coal, wind, natural gas, solar, uranium, tidal.

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Method: Replenished?

Renewable: wind, solar, tidal. Non-renewable: coal, natural gas, uranium
14
Core[2 marks]

State two advantages of wind power.

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Method: Renewable, no fuel cost.

Renewable; no fuel costs; no CO₂ during operation
15
Core[2 marks]

State two disadvantages of wind power.

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Method: Unreliable, visual.

Unreliable (depends on wind); noisy/visual impact; many turbines needed for large output
16
Core[2 marks]

State one advantage and one disadvantage of solar cells.

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Method: Renewable, need sunlight.

Advantage: renewable, no pollution in use. Disadvantage: no output at night/cloudy, low power per area
17
Core[2 marks]

State one advantage and one disadvantage of geothermal energy.

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Method: Reliable, location.

Advantage: reliable, renewable. Disadvantage: only available in certain locations
18
Core[2 marks]

State one advantage and one disadvantage of tidal power.

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Method: Predictable, habitats.

Advantage: reliable and predictable. Disadvantage: affects estuary habitats, few suitable sites
19
Core[2 marks]

State the main energy transfer in a solar cell.

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Method: Light → electrical.

Light energy → electrical energy
20
Core[2 marks]

Describe the energy transfers in a nuclear power station.

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Method: Nuclear → thermal → kinetic → electrical.

Nuclear store → thermal (steam) → kinetic (turbine) → electrical (generator)
21
Core[2 marks]

State why the Sun is described as the ultimate source of most of our energy resources.

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Method: Origin.

Most resources (fossil fuels, wind, waves, biofuels, hydro, solar) depend on energy from the Sun
22
Core[2 marks]

State one environmental problem caused by burning coal.

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Method: CO₂ / acid rain.

Produces CO₂ (global warming) or sulfur dioxide (acid rain)
23
Core[2 marks]

Explain why hydroelectric power is described as reliable.

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Method: Stored water.

Water can be stored and released when needed
24
Core[2 marks]

Explain why electricity demand cannot easily be met using only wind and solar power.

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Method: Variable supply.

Their output varies with the weather and time of day, so supply may not match demand
25
Extended[1 mark]

State which energy resources do not originate from the Sun.

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Method: Syllabus 1.7.3 S4.

Geothermal, nuclear and tidal
26
Extended[1 mark]

State the process that releases energy in the Sun.

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Method: Fusion of hydrogen.

Nuclear fusion
27
Extended[1 mark]

State why research into nuclear fusion power stations is being carried out.

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Method: Large-scale clean energy.

To produce electrical energy on a large scale from fusion
28
Extended[2 marks]

A motor receives 800 J and gives 600 J of useful kinetic energy. Calculate its efficiency.

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Method: Efficiency = useful ÷ total × 100%.

Efficiency = 600 ÷ 800 × 100 = 75.0%
29
Extended[2 marks]

A power station has an input power of 2000 MW and an output power of 700 MW. Calculate its efficiency.

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Method: Use power form.

Efficiency = 700 ÷ 2000 × 100 = 35.0%
30
Extended[3 marks]

A lamp is 15% efficient and gives out 9.0 W of light. Calculate the input power.

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Method: Input = useful ÷ efficiency.

Input = 9.0 ÷ 0.15 = 60.0 W
31
Extended[3 marks]

A kettle is 85% efficient. It receives 200 kJ. Calculate the energy wasted.

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Method: Wasted = 15% of input.

Wasted = 0.15 × 200 = 30.0 kJ
32
Extended[2 marks]

Explain why fossil fuels are said to come originally from the Sun's energy.

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Method: Ancient plants used sunlight.

They formed from plants (and animals) that obtained energy from sunlight by photosynthesis
33
Extended[2 marks]

Calculate the efficiency of a motor that gives 450 J of useful energy from 600 J input.

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Method: Useful/total.

Efficiency = 75.0%
34
Extended[3 marks]

A power station is 35% efficient and produces 700 MW of electrical power. Calculate the input power.

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Method: Input = output ÷ efficiency.

Input = 700 ÷ 0.35 = 2000 MW
35
Extended[3 marks]

An LED lamp is 40% efficient. Its input power is 8.0 W. Calculate the useful output and the wasted power.

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Method: Multiply.

Useful = 3.20 W; wasted = 4.80 W
36
Extended[2 marks]

Explain why efficiency can never be greater than 100%.

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Method: Conservation.

Energy cannot be created, so useful output cannot exceed input
37
Extended[3 marks]

A kettle uses 240 kJ and the water gains 192 kJ. Calculate the efficiency.

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Method: Useful/input.

Efficiency = 192 ÷ 240 × 100 = 80.0%
38
Extended[2 marks]

Explain how the energy in tides originates.

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Method: Moon's gravity.

From the gravitational pull of the Moon (and Sun) on the oceans, not from sunlight
39
Extended[2 marks]

State the nuclear reaction that releases energy in a nuclear power station and compare it with the Sun.

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Method: Fission vs fusion.

Fission of uranium nuclei; the Sun uses fusion of hydrogen nuclei
40
Extended[3 marks]

A solar panel receives 1000 W of light and produces 180 W of electrical power. Calculate its efficiency and the energy wasted per minute.

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Method: Efficiency; wasted power × 60.

Efficiency = 18.0%; wasted = 820 × 60 = 49200 J

Challenge questions

Harder, multi-step questions at the top end of the exam. Attempt these once you are confident with the questions above.

41
ChallengeCore[4 marks]

Compare coal and wind power for providing a country's base-load electricity, giving two points for each.

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Method: Reliability, emissions.

Coal: reliable and available on demand, but non-renewable and emits CO₂. Wind: renewable with no CO₂ in use, but output varies with weather so cannot guarantee base load
42
ChallengeCore[4 marks]

Explain why a mixture of energy resources is used to generate electricity rather than a single resource.

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Method: Reliability and demand.

Some sources (solar, wind) vary; others (hydro, gas) can respond quickly to demand; mixing them gives a reliable supply and reduces dependence on one fuel
43
ChallengeCore[3 marks]

Explain how the energy in coal originally came from the Sun, tracing the energy stores involved.

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Method: Photosynthesis.

Sunlight → chemical store in ancient plants (photosynthesis) → buried and compressed into coal → chemical store released on burning
44
ChallengeCore[4 marks]

A hydroelectric dam stores water 120 m above the turbines. Explain how this is used to meet sudden demand and give one environmental cost.

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Method: Store and release.

Water can be released within seconds to drive turbines when demand rises; building the dam floods valleys and destroys habitats
45
ChallengeExtended[4 marks]

A power station burns fuel releasing 2500 MJ per second and has an efficiency of 38%. Calculate the electrical power output and the wasted energy per second.

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Method: Efficiency × input.

Output = 950 MW; wasted = 1550 MJ per second
46
ChallengeExtended[4 marks]

A wind turbine has an input power of 2.5 MW from the wind and an output of 1.0 MW. Calculate its efficiency and the energy produced in a day if it runs at this output for 18 hours.

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Method: E = Pt.

Efficiency = 40.0%; E = 1.0 × 10⁶ × 18 × 3600 = 6.48 × 10¹⁰ J
47
ChallengeExtended[4 marks]

A solar panel of area 1.6 m² receives 900 W/m² and is 20% efficient. Calculate the electrical power output and the energy produced in 5 hours in kW h.

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Method: Input = 900 × 1.6.

P = 1440 × 0.20 = 288 W; E = 1.44 kW h
48
ChallengeExtended[3 marks]

Explain why nuclear fusion power stations, if developed, would be an improvement on fission stations.

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Method: Fuel, waste.

Fuel (hydrogen isotopes) is plentiful; far less long-lived radioactive waste; no CO₂
49
ChallengeExtended[4 marks]

An electric motor is 70% efficient and must provide 1400 J of useful work each second. Calculate the input power and the rate of energy wasted.

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Method: Input = useful/efficiency.

Input = 2000 W; wasted = 600 W
50
ChallengeExtended[4 marks]

Explain why geothermal, tidal and nuclear energy are the only resources in the syllabus that do not originate from the Sun, stating the source of each.

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Method: Different origins.

Geothermal: heat from radioactive decay in the Earth; tidal: gravitational pull of the Moon (and Sun) on oceans; nuclear: energy stored in nuclei of fuels like uranium
All IGCSE Physics topics← 1.7.2 Work1.7.4 Power →

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