IGCSE Physics 0625 Paper 4 Practice Paper (Extended, 80 marks)

Level: Year 10–11 (IGCSE) | Subject: Physics 0625 | Time: 75 minutes | Total: 80 marks | Parts: 30

Paper at a glance

Paper	Time	Marks	Weighting
Paper 4 (Extended, structured)	1 h 15 min	80	50%%

Questions

Question 1 (12 marks) — Forces and motion

(a) A car of mass 1200 kg travels at 5.0 m/s along a level road. Calculate the momentum of the car before it accelerates. (2 marks)

(b) The driver takes 8.0 s to raise the speed from 5.0 m/s to 25 m/s. Calculate the average acceleration. (2 marks)

(c) Calculate the resultant force on the car during this acceleration. (2 marks)

(d) Calculate the distance travelled during the 8.0 s acceleration, using average speed. (3 marks)

(e) On a wet road the same car needs a longer distance to stop. Explain this in terms of force and motion. (3 marks)

Question 2 (13 marks) — Thermal physics and energy

(a) 2.0 kg of water is heated from 20 °C to 60 °C. The specific heat capacity of water is 4200 J/(kg °C). Calculate the energy gained by the water. (3 marks)

(b) An electric kettle rated at 2400 W has no energy loss. Calculate the time needed to heat this water to 60 °C. (2 marks)

(c) In practice the kettle is only 80% efficient. Calculate the actual time needed. (2 marks)

(d) State three ways in which energy is lost during heating. (3 marks)

(e) Explain why a vacuum flask reduces energy loss. (3 marks)

Question 3 (13 marks) — Waves and light

(a) A sound wave has frequency 500 Hz and wavelength 0.68 m. Calculate its speed. (2 marks)

(b) Light passes from air into glass with an angle of incidence of 40° and an angle of refraction of 25°. Calculate the refractive index of the glass. (3 marks)

(c) Calculate the period of this sound wave. (2 marks)

(d) State the two conditions for total internal reflection. (3 marks)

(e) Radio waves can bend around hills but visible light cannot. Explain using diffraction. (3 marks)

Question 4 (13 marks) — Electricity

(a) A 6.0 ohm resistor and a 3.0 ohm resistor are connected in parallel to a 12 V supply. Calculate the combined resistance. (3 marks)

(b) Calculate the total current from the supply. (2 marks)

(c) Calculate the total power of the circuit. (2 marks)

(d) The resistance of a filament lamp increases as it warms up. Explain this in terms of conduction in metals. (3 marks)

(e) Explain how a fuse protects an appliance. (3 marks)

Question 5 (12 marks) — Pressure and molecular motion

(a) A force of 500 N acts normally on an area of 0.02 m². Calculate the pressure. (2 marks)

(b) A diver is 1.5 m below the surface of a pool. Water density is 1000 kg/m³, g = 10 N/kg and atmospheric pressure is 100 kPa. Calculate the absolute pressure on the diver. (3 marks)

(c) A diver must not rise quickly from a great depth. Explain using the solubility of gases. (2 marks)

(d) Explain, in terms of molecular motion, why wet skin feels cool in a breeze. (3 marks)

(e) State the definition of density and its SI unit. (2 marks)

Question 6 (17 marks) — Radioactivity and energy

(a) A source contains 80 g of a nuclide of half-life 6.0 hours. Calculate the time for the mass remaining to fall to 10 g. (3 marks)

(b) The count rate from this nuclide falls from 640 counts per minute to 40 counts per minute. Calculate the time taken. (3 marks)

(c) Compare the penetrating power of alpha, beta and gamma radiation. (3 marks)

(d) A 2400 W heater works continuously for 300 s. Calculate the energy transferred and state how conservation of energy applies. (4 marks)

(e) Suggest two safety precautions when handling a radioactive source, each with a reason. (4 marks)

Answers and marking notes

Question 1 — Forces and motion

(a) p = m v = 1200 x 5.0 = 6000 kg m/s (2; 1 only if the unit is missing or wrong). [2 marks]

(b) a = (v – u) / t = (25 – 5.0) / 8.0 = 2.5 m/s² (2). [2 marks]

(c) F = m a = 1200 x 2.5 = 3000 N (2). [2 marks]

(d) Average speed = (5.0 + 25) / 2 = 15 m/s (1); distance = 15 x 8.0 = 120 m (2). Award 2 if the answer appears with no working. [3 marks]

(e) Friction (braking force) is smaller on a wet road (1); so the deceleration is smaller for the same mass (1); since v² = u² + 2as, the stopping distance s is larger for the same initial speed (1). [3 marks]

Question 2 — Thermal physics and energy

(a) dT = 60 – 20 = 40 °C (1); E = m c dT = 2.0 x 4200 x 40 = 336000 J (2). [3 marks]

(b) t = E / P = 336000 / 2400 = 140 s (2; 1 if the division by power is missing). [2 marks]

(c) Useful power = 2400 x 0.80 = 1920 W; t = 336000 / 1920 = 175 s (2). [2 marks]

(d) Heating the body and handle of the kettle; heating the surrounding air by convection; latent heat carried away by water vapour. 1 mark each, any three. [3 marks]

(e) The vacuum between the walls contains almost no particles, so conduction and convection cannot occur (2); shiny walls reduce radiation (1). [3 marks]

Question 3 — Waves and light

(a) v = f x wavelength = 500 x 0.68 = 340 m/s (2). [2 marks]

(b) n = sin i / sin r = sin 40 / sin 25 = 0.643 / 0.423 = 1.52 (3; 1 only if inverted as sin r / sin i, giving 0.66). [3 marks]

(c) T = 1 / f = 1 / 500 = 0.002 s (2; 2.0 x 10-3 s is also accepted). [2 marks]

(d) Light travels from a denser to a less dense medium (1); the angle of incidence exceeds the critical angle (1); no refracted ray emerges and all the energy is reflected (1). [3 marks]

(e) The amount of diffraction depends on the ratio of wavelength to obstacle size (1); radio wavelengths are of the order of metres, similar to a hill, so diffraction is marked (1); visible light has a very short wavelength, so it diffracts very little (1). [3 marks]

Question 4 — Electricity

(a) 1 / R = 1 / 6.0 + 1 / 3.0 = 0.5 per ohm (1); R = 1 / 0.5 = 2.0 ohm (2). [3 marks]

(b) I = V / R = 12 / 2.0 = 6 A (2). [2 marks]

(c) P = V I = 12 x 6.0 = 72 W (2; P = V²/R is equally acceptable). [2 marks]

(d) Higher temperature makes the metal ions vibrate more (1); free electrons therefore collide with ions more frequently (1); so resistance rises (1). [3 marks]

(e) The fuse is in series with the appliance (1); an excessive current melts the fuse and breaks the circuit (1); its rating is just above the normal operating current (1). [3 marks]

Question 5 — Pressure and molecular motion

(a) p = F / A = 500 / 0.02 = 25000 Pa (2). [2 marks]

(b) Water pressure = rho g h = 1000 x 10 x 1.5 = 15000 Pa = 15 kPa (2); absolute pressure = 100 + 15 = 115000 Pa = 115 kPa (1). Only the water pressure, with no atmospheric term, scores 2. [3 marks]

(c) The high pressure at depth dissolves more gas in the blood (1); on rapid ascent the pressure falls and bubbles of gas form (1). [2 marks]

(d) The fastest molecules escape during evaporation (1); the average kinetic energy of the remaining liquid falls, so its temperature falls (1); a breeze removes the vapour so evaporation continues faster (1). [3 marks]

(e) Mass per unit volume (1); SI unit kg/m³ (1). [2 marks]

Question 6 — Radioactivity and energy

(a) 80 -> 40 -> 20 -> 10, i.e. 3 half-lives (2); t = 3 x 6.0 = 18 hours (1). [3 marks]

(b) 640 -> 320 -> 160 -> 80 -> 40, i.e. 4 half-lives (2); t = 4 x 6.0 = 24 hours (1). [3 marks]

(c) Alpha is least penetrating, stopped by a sheet of paper (1); beta is intermediate, stopped by a few millimetres of aluminium (1); gamma is most penetrating and needs thick lead to be appreciably reduced (1). [3 marks]

(d) E = P t = 2400 x 300 = 720000 J (2); conservation of energy: the electrical energy becomes internal energy (and a little sound) with no net loss (2). [4 marks]

(e) Use tongs and keep the exposure time short (1) to reduce the dose received (1); store the source in a lead container (1) to shield gamma radiation (1). Other sensible answers score equally. [4 marks]

Download

Question paper PDF · Answer key PDF

Book a tutor-led paper review →