AQA GCSE Physics — Paper 2 (Higher Tier)

Total marks: 100 · Duration: 105 minutes · Tier: higher

Instructions to candidates

Answer all questions in the spaces provided.
You are expected to use a calculator.
This paper covers Topics 5–8: Forces, Waves, Magnetism and Electromagnetism, and Space Physics.
The maximum mark for this paper is 100. The marks for each question are shown in brackets.

Paper

Section A — Multiple Choice (6 marks)

1. Momentum is calculated using: (1 mark) A) mass × velocity B) mass × acceleration C) force × distance D) mass ÷ velocity

2. The turning effect of a force is called a: (1 mark) A) couple B) moment C) torque limit D) pivot

3. A convex lens is also known as a: (1 mark) A) diverging lens B) converging lens C) concave lens D) plane lens

4. A step-up transformer: (1 mark) A) decreases voltage B) increases voltage C) changes d.c. to a.c. D) has no effect

5. Stars form from a cloud of dust and gas called a: (1 mark) A) supernova B) nebula C) black hole D) red giant

6. Red-shift of light from distant galaxies is evidence that the universe is: (1 mark) A) contracting B) static C) expanding D) cooling only

Section B — Structured Questions (60 marks)

7. Forces can change momentum. (a) Calculate the momentum of a 1500 kg car travelling at 12 m/s. (2 marks) (b) State the principle of conservation of momentum. (1 mark) (c) Explain how a car's crumple zone reduces the force on the passengers in a crash. (3 marks)

8. Moments and pressure act in everyday situations. (a) Calculate the moment of a 40 N force applied 0.5 m from a pivot. (2 marks) (b) State the principle of moments for a balanced object. (1 mark) (c) Explain why the pressure in a liquid increases with depth. (2 marks)

9. Waves can be reflected and refracted. (a) Calculate the speed of a wave with frequency 25 Hz and wavelength 8 m. (2 marks) (b) Explain what happens to the speed and direction of light entering glass from air. (2 marks) (c) Describe how a convex lens forms a real image, and define a real image. (3 marks)

10. All objects emit and absorb radiation. (a) State which surfaces are the best emitters and absorbers of infrared radiation. (1 mark) (b) Explain how the temperature of an object stays constant in terms of radiation. (2 marks)

11. Electromagnetic induction is used in generators and transformers. (a) Describe how a potential difference can be induced in a wire. (2 marks) (b) State two ways to increase the size of the induced potential difference. (2 marks) (c) A transformer has 100 turns on the primary and 500 on the secondary. The primary voltage is 230 V. Calculate the secondary voltage. (3 marks)

12. Stars have a life cycle. (a) Describe how a main sequence star is formed from a nebula. (3 marks) (b) Explain what keeps a main sequence star stable. (2 marks) (c) Describe what happens to a star much more massive than the Sun at the end of its life. (3 marks)

13. The universe is expanding. (a) Explain what is meant by red-shift. (2 marks) (b) State two pieces of evidence for the Big Bang theory. (2 marks)

Section C — Extended Response

14. Explain how the National Grid transmits electrical power efficiently over long distances, including the role of transformers. (6 marks)

Mark Scheme

Section A: 1. A; 2. B; 3. B; 4. B; 5. B; 6. C. (6)

7 (a) p = mv = 1500 × 12 = 18 000 kg m/s (1 method, 1 answer). (b) total momentum before = total momentum after, in a closed system (1). (c) the crumple zone increases the time of the collision (1); for the same change in momentum, a longer time means a smaller force (1); reducing the force on the passengers (1). (6)

8 (a) moment = F × d = 40 × 0.5 = 20 Nm (1 method, 1 answer). (b) total clockwise moment = total anticlockwise moment (1). (c) greater depth → greater weight of liquid above (1) → greater pressure (1). (5)

9 (a) v = fλ = 25 × 8 = 200 m/s (1 method, 1 answer). (b) light slows down (1); bends towards the normal (1). (c) parallel rays are refracted to meet at the principal focus (1); a real image can be projected onto a screen (1); it forms where the rays actually meet (1). (7)

10 (a) matt black surfaces (1). (b) it emits radiation at the same rate as it absorbs it (1); so there is no net change in energy/temperature (1). (3)

11 (a) move a wire/magnet relative to each other / change the field through a coil (1); this induces a potential difference (1). (b) any two: move faster; stronger magnet; more turns; larger coil area (2). (c) Vp/Vs = Np/Ns → 230/Vs = 100/500 (1); Vs = 230 × 5 (1) = 1150 V (1). (7)

12 (a) gravity pulls a nebula (dust and gas) together (1); it heats up forming a protostar (1); fusion begins → main sequence star (1). (b) inward gravity is balanced by outward pressure from fusion energy (2). (c) becomes a red supergiant (1); explodes as a supernova (1); leaves a neutron star or black hole (1). (8)

13 (a) light from distant galaxies is shifted to longer/red wavelengths (1); because they are moving away from us (1). (b) red-shift; cosmic microwave background radiation (2). (4)

14 — Levels (6): Indicative: step-up transformers increase the voltage for transmission; for a given power, higher voltage means lower current; energy loss as heat in cables depends on current², so lower current = less wasted energy; step-down transformers reduce the voltage for safe use; transformers require a.c.

L3 (5–6): Links high voltage → low current → less heat loss, and correctly uses step-up/step-down transformers.

L2 (3–4): Some of the chain or the role of transformers.

L1 (1–2): Simple statements.

Sample Answers with Examiner Commentary

Question 14 — Sample Answers

Grade 9 answer "At the power station a step-up transformer increases the potential difference to a very high value for transmission. For a fixed amount of power, P = VI, so increasing the voltage means a much lower current flows in the cables. The energy wasted as heat in the cables depends on the current squared, so reducing the current greatly reduces the energy lost, making transmission efficient. Near homes and businesses, step-down transformers reduce the voltage again to a safe value (around 230 V). Transformers only work with alternating current, which is why the mains supply is a.c." Mark: 6/6. Examiner commentary: The full efficiency chain (high voltage → low current → less heat loss) is explained, with the correct role of both transformer types and the a.c. requirement. Top band.

Grade 6 answer "Step-up transformers make the voltage high for the wires and step-down transformers lower it for houses. High voltage means less energy is wasted as heat." Mark: 4/6. Examiner commentary: Correct roles of the transformers and the conclusion, but it does not explain that high voltage allows a lower current, which is why less heat is lost. That link is needed for the top band.

Question 11(c) — Sample Answers

Grade 9 answer "Vp/Vs = Np/Ns, so 230/Vs = 100/500. Rearranging, Vs = 230 × (500/100) = 230 × 5 = 1150 V." Mark: 3/3. Examiner commentary: Correct equation, substitution and answer with the unit.