Edexcel IGCSE Physics: Energy Resources and Energy Transfers — Practice Questions

These are original questions written for Marlbridge, in the style and at the standard of the examination. They are not reproduced past-paper questions — examination boards hold copyright in their own papers. Use these alongside the official past papers available free from your board.

Related: Energy revision notes

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Questions

1. Name four energy stores and the four ways energy can be transferred between them. [4]

2. A student writes “light energy is a store of energy.” Explain why this is wrong. [2]

3. State the principle of conservation of energy, and explain what actually happens to “wasted” energy. [3]

4. A motor lifts a 25 kg load through 3.2 m in 8.0 s using 1600 J of electrical energy. (g = 10 N kg⁻¹)

(a) Calculate the useful energy output. [2] (b) Calculate the efficiency. [2] (c) Calculate the input power. [2] (d) Suggest where the wasted energy goes. [2]

5. Explain the mechanism of:

(a) conduction in a metal, and why metals conduct far better than non-metals [3] (b) convection in a liquid [3] (c) why radiation is the only method that works through a vacuum [2]

6. Explain why a matt black surface is both the best emitter and the best absorber of infrared radiation. [2]

7. Compare wind power and gas-fired power stations on reliability, environmental impact and cost. [6]

8. A person pushes a crate with a force of 45 N, moving it 6.0 m in the direction of the force across a horizontal floor. Calculate the work done. [2]

9. A car of mass 900 kg travels at 20 m s⁻¹ along a straight, level road. Calculate its kinetic energy. [2]

10. Classify geothermal power and nuclear power as renewable or non-renewable, giving a reason for each, and state the main environmental or safety concern specific to nuclear power that does not apply to burning fossil fuels. [3]

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Answers

1. Any four stores: kinetic, gravitational potential, elastic potential, chemical, thermal, nuclear [1] [1]. Transfers: mechanically, electrically, by heating, by radiation [1] [1].

2. Light is a transfer pathway, not a store [1] — it is a way energy moves between stores, rather than somewhere energy is held [1].

3. Energy cannot be created or destroyed, only transferred between stores [1]. “Wasted” energy is dissipated to the thermal store of the surroundings [1], where it becomes spread out and too dilute to be useful — it is not destroyed [1].

4. (a) E = mgh = 25 × 10 × 3.2 [1] = 800 J [1]. (b) efficiency = 800 ÷ 1600 [1] = 0.5 or 50% [1]. (c) P = E ÷ t = 1600 ÷ 8.0 [1] = 200 W [1]. (d) To the thermal store of the surroundings through friction in the motor and bearings [1], and as sound [1].

5. (a) Particles vibrate more when heated and pass energy to neighbours [1]. Metals contain delocalised free electrons [1] that move through the structure carrying energy far faster than vibration alone [1]. (b) The heated liquid expands and becomes less dense [1], so it rises [1]; cooler, denser liquid sinks to replace it, setting up a convection current [1]. (c) Radiation is an electromagnetic wave [1] and requires no medium, whereas conduction and convection both need particles [1].

6. A matt black surface absorbs almost all the infrared radiation falling on it rather than reflecting it [1], and by the same physical property it also emits infrared efficiently — good absorbers are good emitters [1].

7. Reliability: gas is reliable and can be started quickly on demand [1]; wind is intermittent, depending on weather [1]. Environmental: gas releases carbon dioxide contributing to global warming [1]; wind produces no emissions in operation but causes visual and noise impact [1]. Cost: gas has lower setup costs but ongoing fuel costs [1]; wind has high setup costs but almost no running costs [1].

8. W = F × d = 45 × 6.0 [1] = 270 J [1].

9. E_k = ½mv² = 0.5 × 900 × 20² [1] = 180 000 J [1].

10. Geothermal is renewable — it draws on heat from the Earth’s interior, which does not deplete a finite reserve [1]. Nuclear is non-renewable — it depletes a finite reserve of uranium fuel, even though it produces no carbon dioxide during operation [1]. Nuclear’s specific concern is radioactive waste and the risk of a serious accident, neither of which applies to burning fossil fuels (whose main concern is carbon emissions instead) [1].

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Where marks are usually lost

• Calling heat or light an energy store.
• Saying energy is “lost”.
• Explaining metal conduction without free electrons.
• Comparing energy resources on one dimension only.
• In Q8, forgetting that the work done against friction is dissipated to the thermal energy store of the crate and floor, not stored anywhere — there is no stored quantity for it to equal. Always check that the distance used is measured in the direction of the applied force, not just the total path travelled.
• Classifying nuclear power as renewable because it does not burn fossil fuels — it is non-renewable because its fuel reserve is finite.

Work through the Energy revision notes alongside these questions: the notes summarise the stores, transfers and resource classifications in condensed form, while these questions test whether you can apply the work, kinetic-energy and renewable/non-renewable definitions to a specific example rather than just recall them.