F6 Student (2026)_Physics_Pre-Course Test_2 October 2026

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HKDSE Physics Pre-Course Diagnostic Test | F6 Student (2026)

HKDSE Physics — Pre-Course Diagnostic Test

Subject: Physics

Purpose: Pre-Course Test

F6 Student (2026)

Issue date: Friday, 2 October 2026

Total: 75 marks  |  Suggested time: 80–90 minutes  |  Unless otherwise stated, g = 10 m s−2

01

Section A — Five Compulsory Topics

True or False

For each statement, state whether it is True or False. No explanation is required. (1 mark each)

Heat and Gases

  1. Two objects at the same temperature must have the same internal energy.
  2. When a pure solid melts at its melting point, its temperature remains constant but its internal energy increases.
  3. Evaporation can occur only when a liquid reaches its boiling point.
  4. For a fixed mass of gas kept at constant volume, doubling its absolute temperature doubles its pressure, provided that the gas behaves ideally.
  5. A shiny silver surface is generally both a poor emitter and a poor absorber of infrared radiation.

Force and Motion

  1. An object moving at constant speed must have zero acceleration.
  2. If the resultant force acting on an object is zero, the object may still be moving.
  3. An action force and its corresponding reaction force cancel each other because they are equal and opposite.
  4. During an isolated collision, total momentum is conserved even if total kinetic energy is not conserved.
  5. In the absence of air resistance, a heavier object falls with a greater acceleration than a lighter object.

Wave Motion

  1. When a wave crosses from one medium into another, both its frequency and wavelength change.
  2. A water wave entering a region where its speed is lower bends towards the normal.
  3. Diffraction is generally most significant when the width of a gap is comparable to or smaller than the wavelength.
  4. After two waves meet and interfere constructively, they remain permanently combined as one wave of greater amplitude.
  5. Sound cannot travel through a vacuum because there are no particles to transmit the vibration.

Electricity and Magnetism

  1. Electric current becomes smaller after passing through a resistor because some of the current is used up.
  2. An ideal voltmeter has a very high resistance and is connected in parallel with the component being measured.
  3. Adding another resistor in parallel across an ideal power supply decreases the equivalent resistance and increases the total current.
  4. A transformer can operate normally when connected to a steady direct-current supply.
  5. The magnetic force on a straight current-carrying wire is zero if the wire is parallel to the magnetic field.

Radioactivity and Nuclear Energy

  1. The decay rate of a radioactive sample is not significantly affected by changes in temperature, pressure or chemical state.
  2. Alpha radiation normally has a greater penetrating power than beta radiation.
  3. After one half-life, exactly half of the original radioactive nuclei have decayed.
  4. A reading obtained from a radiation detector normally includes both radiation from the source and background radiation.
  5. Nuclear fission is the process in which two light nuclei combine to form a heavier nucleus.
25 marks
02

Section B — Comprehensive Structured Question 1

Heat and Gases

A constant-volume gas thermometer uses the pressure of a fixed mass of gas as its temperature-dependent property. The following readings are obtained:

Fixed point Temperature Gas pressure
Ice point0 °C96.0 kPa
Steam point100 °C132.0 kPa

Assume that the gas pressure varies linearly with Celsius temperature.

Pressure p / kPa Temperature θ / °C 132.0 96.0 0 100 Ice point Steam point
Fig. 1 — Gas pressure at the two fixed points (pressure axis not drawn to scale)

(a) Calculate the pressure of the gas at 25.0 °C. (2 marks)

(b) When the gas pressure is 114.0 kPa, determine the temperature indicated by the thermometer. (2 marks)

A separate sample of ideal gas has an initial volume of 2.40 × 10−3 m3 at the temperature found in part (b). The gas is heated to 127 °C while its pressure remains constant.

(c) Calculate the final volume of the gas. (3 marks)

(d) During the heating process, a heater supplies 2400 J of energy to the gas. The gas does 65 J of work on its surroundings. Calculate the increase in the internal energy of the gas. (2 marks)

(e) Explain why absolute temperatures, rather than Celsius temperatures, must be used in the gas-law calculation in part (c). (1 mark)

10 marks
03

Section B — Comprehensive Structured Question 2

Force and Motion

A 2.0 kg trolley is initially at rest on a horizontal track. From t = 0 to t = 4.0 s, a constant resultant force of 3.0 N acts on the trolley.

(1) 0 to 4.0 s: starts from rest 2.0 kg resultant force 3.0 N (2) 4.0 s to 10.0 s: constant speed 2.0 kg pulling force F resistive force 2.0 N (3) t = 10.0 s: collision, then slope 2.0 kg moving 1.0 kg at rest frictionless slope h
Fig. 2 — The motion of the trolleys (not drawn to scale)

(a) Calculate the acceleration of the trolley. (1 mark)

(b) Calculate: (2 marks)

  1. the speed of the trolley at t = 4.0 s;
  2. the distance travelled during the first 4.0 s.

From t = 4.0 s to t = 10.0 s, the trolley moves at a constant speed. A constant resistive force of 2.0 N acts on it.

(c) Determine the pulling force exerted by the motor during this interval. (1 mark)

At t = 10.0 s, the trolley collides with a stationary 1.0 kg trolley. The two trolleys lock together.

(d) Calculate their common speed immediately after the collision. (2 marks)

(e) Calculate the kinetic energy lost during the collision. (2 marks)

The combined trolleys then move up a frictionless slope.

(f) Calculate the maximum vertical height reached by the combined trolleys. (2 marks)

10 marks
04

Section B — Comprehensive Structured Question 3

Wave Motion

Straight water waves of frequency 12 Hz travel from a deep region into a shallow region of a ripple tank. The wavelength in the deep region is 3.0 cm, while that in the shallow region is 2.0 cm. The angle of incidence at the boundary is 40°.

boundary Deep region (λ = 3.0 cm) Shallow region (λ = 2.0 cm) normal incident ray i = 40° refracted ray r
Fig. 3 — Top view of water waves crossing the boundary in a ripple tank (not drawn to scale)

(a) Calculate the wave speed in the deep region. (2 marks)

(b) State the frequency of the waves in the shallow region. Explain your answer. (2 marks)

(c) Calculate the angle of refraction in the shallow region. (3 marks)

You may use:

sin isin r = vdeepvshallow

(d) State whether the waves bend towards or away from the normal. (1 mark)

The waves in the shallow region then pass through a gap of width 2.0 cm.

(e) State whether significant diffraction is expected. Explain your answer by comparing the gap width with the wavelength. (2 marks)

10 marks
05

Section B — Comprehensive Structured Question 4

Electricity and Magnetism

A cell of unknown electromotive force E and internal resistance r is connected to a variable resistor.

When the external resistance is 5.0 Ω, the terminal potential difference is 10.0 V. When the external resistance is changed to 2.0 Ω, the terminal potential difference becomes 8.0 V. Assume that the connecting wires and ammeter have negligible resistance.

A V E r cell R
Fig. 4 — Circuit diagram: cell (with internal resistance r), ammeter, variable resistor R and voltmeter

(a) Calculate the current in the circuit for each of the following external resistances: (2 marks)

  1. 5.0 Ω;
  2. 2.0 Ω.

(b) Using E = V + Ir, determine: (4 marks)

  1. the internal resistance r;
  2. the electromotive force E.

(c) The external resistance is now changed to 3.0 Ω. Calculate: (3 marks)

  1. the current in the circuit;
  2. the power delivered to the external resistor.

(d) A 2.5 A fuse is connected in series with the circuit in part (c). State what happens to the fuse. (1 mark)

10 marks
06

Section B — Comprehensive Structured Question 5

Radioactivity and Nuclear Energy

A student uses a Geiger–Müller tube and counter to investigate a radioactive source. The background count rate is measured as 24 counts per minute. The following readings are then recorded:

Time / min Measured count rate / counts per minute
0824
6424
12224
Source radioactive source absorber (paper or aluminium) GM tube window Counter
Fig. 5 — Apparatus used to measure count rates (not drawn to scale)

(a) Explain why the background count rate should be measured and subtracted from the recorded readings. (2 marks)

(b) Use the corrected count rates to determine the half-life of the source. Show your reasoning. (2 marks)

(c) Estimate the detector reading, including background radiation, at t = 18 min. (2 marks)

(d) Calculate the fraction of the original radioactive nuclei expected to remain undecayed after 15 min. (2 marks)

In a separate absorption experiment, the following readings are obtained over equal time intervals. Any decrease due to radioactive decay has already been corrected. The background count rate is 24 counts per minute.

Absorber Detector reading / counts per minute
No absorber824
Sheet of paper818
3 mm aluminium29

(e) Identify the main type of radiation emitted by the source. Explain your answer. (2 marks)

10 marks

Question 1 — True or False

Heat and Gases

  1. False. Equal temperature does not imply equal mass, state or internal energy.
  2. True. Energy increases molecular potential energy during melting.
  3. False. Evaporation can occur at temperatures below the boiling point.
  4. True. At constant volume, p ∝ T, where T is the absolute temperature.
  5. True. A good reflector is generally a poor absorber and a poor emitter of radiation.

Force and Motion

  1. False. The direction of the velocity may change, as in circular motion.
  2. True. Zero resultant force means zero acceleration, not necessarily zero velocity.
  3. False. Action and reaction act on different objects, so they cannot cancel each other.
  4. True. Momentum is conserved in an isolated system, including in an inelastic collision.
  5. False. Without air resistance, all objects have the same gravitational acceleration.

Wave Motion

  1. False. Frequency remains unchanged when a wave enters another medium; the speed and wavelength change.
  2. True. A wave bends towards the normal when its speed decreases.
  3. True. Diffraction is significant when the gap width is comparable to or less than the wavelength.
  4. False. The waves overlap temporarily and then continue travelling.
  5. True. Mechanical waves require a medium.

Electricity and Magnetism

  1. False. Charge and current are not used up; electrical energy is transferred.
  2. True. A high resistance minimises the current drawn by the voltmeter.
  3. True. A parallel connection lowers the equivalent resistance, so the total current increases.
  4. False. A transformer requires a changing current and hence a changing magnetic flux.
  5. True. F = BIl sin θ; the force is zero when θ = 0°.

Radioactivity and Nuclear Energy

  1. True. Nuclear decay is largely independent of physical and chemical conditions.
  2. False. Alpha radiation has a lower penetrating power than beta radiation.
  3. True. Statistically, half of a very large number of nuclei are expected to decay in one half-life.
  4. True. Background radiation contributes to the recorded count.
  5. False. This describes fusion. Fission is the splitting of a heavy nucleus.
Note on statement 23: For the expected HKDSE interpretation, the statement is true for a large sample in a statistical sense. A strong student may note that it is not guaranteed that exactly half the nuclei in a small sample will decay. Credit such an answer if it is properly explained.

Question 2 — Heat and Gases

(a) Pressure at 25.0 °C

Pressure increase from 0 °C to 100 °C = 132.0 − 96.0 = 36.0 kPa
p = 96.0 + (25.0 ÷ 100)(36.0) (1)
p = 105.0 kPa (1)

(b) Temperature at 114.0 kPa

θ ÷ 100 = (114.0 − 96.0) ÷ (132.0 − 96.0) = 18.0 ÷ 36.0 (1)
θ = 50.0 °C (1)

(c) Final volume

T1 = 50 + 273 = 323 K
T2 = 127 + 273 = 400 K (1)
At constant pressure: V1 ÷ T1 = V2 ÷ T2
V2 = 2.40 × 10−3 × (400 ÷ 323) (1)
V2 = 2.97 × 10−3 m3 (1)

(d) Increase in internal energy

ΔU = Q − W, where W is the work done by the gas (1)
ΔU = 2400 − 65 = 2335 J (1)

(e) Use of absolute temperature

Gas-law proportionalities use temperature measured from absolute zero. Celsius temperature is not directly proportional to the average molecular kinetic energy. (1)

Marking note: In (c), accept 273.15 K for the conversion; the final answer is still 2.97 × 10−3 m3 to three significant figures.

Question 3 — Force and Motion

(a) Acceleration

a = F ÷ m = 3.0 ÷ 2.0 = 1.5 m s−2 (1)

(b) Speed and distance

  1. v = u + at = 0 + (1.5)(4.0) = 6.0 m s−1 (1)
  2. s = ut + ½at2 = 0 + ½(1.5)(4.0)2 = 12 m (1)

(c) Pulling force

The trolley has constant velocity, so the resultant force is zero. Pulling force = resistive force = 2.0 N. (1)

(d) Common speed after the collision

By conservation of momentum:
(2.0)(6.0) + (1.0)(0) = (2.0 + 1.0)v (1)
12 = 3.0v
v = 4.0 m s−1 (1)

(e) Kinetic energy lost

Ek, before = ½(2.0)(6.0)2 = 36 J
Ek, after = ½(3.0)(4.0)2 = 24 J (1)
Kinetic energy lost = 36 − 24 = 12 J (1)

(f) Maximum vertical height

All the kinetic energy is converted into gravitational potential energy:
½mv2 = mgh (1)
h = v2 ÷ 2g = 4.02 ÷ 2(10) = 0.80 m (1)

Question 4 — Wave Motion

(a) Wave speed in the deep region

v = fλ = (12)(3.0 × 10−2) (1)
v = 0.36 m s−1 (1)

(b) Frequency in the shallow region

f = 12 Hz (1)

The frequency is determined by the source and does not change when the waves cross the boundary. (1)

(c) Angle of refraction

Since the frequency is unchanged,
vshallowvdeep = λshallowλdeep = 2.03.0 (1)
sin isin r = vdeepvshallow
sin r = sin 40° × 2.03.0 (1)
sin r = 0.4285
r ≈ 25° (1)

(d) Direction of bending

The waves bend towards the normal, because their speed decreases in the shallow region. (1)

(e) Diffraction at the gap

Yes, significant diffraction is expected. (1)

The gap width is 2.0 cm, which is equal to the wavelength in the shallow region (2.0 cm). Diffraction is significant when the gap width is comparable to or smaller than the wavelength. (1)

Question 5 — Electricity and Magnetism

(a) Current in the circuit

  1. R = 5.0 Ω: I = V ÷ R = 10.0 ÷ 5.0 = 2.0 A (1)
  2. R = 2.0 Ω: I = 8.0 ÷ 2.0 = 4.0 A (1)

(b) Internal resistance and e.m.f.

First set of readings: E = 10.0 + 2.0r (1)
Second set of readings: E = 8.0 + 4.0r (1)
10.0 + 2.0r = 8.0 + 4.0r
2.0 = 2.0r
  1. r = 1.0 Ω (1)
  2. E = 10.0 + (2.0)(1.0) = 12.0 V (1)

(c) External resistance of 3.0 Ω

  1. Rtotal = 3.0 + 1.0 = 4.0 Ω (1)
    I = E ÷ Rtotal = 12.0 ÷ 4.0 = 3.0 A (1)
  2. P = I2R = (3.0)2(3.0) = 27 W (1)

(d) Fuse

The current is 3.0 A, which exceeds the fuse rating of 2.5 A. The fuse melts and breaks the circuit. (1)

Question 6 — Radioactivity and Nuclear Energy

(a) Background radiation

  • Background radiation also produces counts in the detector. (1)
  • It must be subtracted so that the corrected count rate represents radiation from the source alone. (1)

(b) Half-life

t = 0: 824 − 24 = 800 min−1
t = 6: 424 − 24 = 400 min−1
t = 12: 224 − 24 = 200 min−1 (1)
The corrected count rate halves every 6 minutes, so t½ = 6 min. (1)

(c) Reading at t = 18 min

Corrected count rate = 200 ÷ 2 = 100 min−1 (1)
Including background: 100 + 24 = 124 counts per minute (1)

(d) Fraction remaining after 15 min

Number of half-lives: n = 15 ÷ 6 = 2.5
Fraction remaining = (½)2.5 (1)
= 0.177 (approximately 17.7%) (1)

(e) Type of radiation

  • The source mainly emits beta radiation. (1)
  • The paper produces almost no decrease in the count rate (824 → 818), but 3 mm of aluminium reduces it to approximately the background level (29 compared with 24). Beta radiation can penetrate paper but is absorbed by a few millimetres of aluminium. (1)

Diagnostic Profile

Combine the five True/False marks and the corresponding structured-question mark for each topic.

Topic True/False Structured Total
Heat and GasesQ1–5Structured Q1/15
Force and MotionQ6–10Structured Q2/15
Wave MotionQ11–15Structured Q3/15
Electricity and MagnetismQ16–20Structured Q4/15
Radioactivity and Nuclear EnergyQ21–25Structured Q5/15

Suggested interpretation for each topic

Score Diagnostic interpretation
13–15Strong understanding; ready for more difficult HKDSE applications
10–12Generally sound, but has some conceptual or calculation weaknesses
7–9Partial understanding; substantial revision is recommended
4–6Weak foundation in this topic
0–3Major knowledge gap; systematic reteaching is required

Overall interpretation

Total score Suggested interpretation
64–75Strong starting point
51–63Suitable foundation, with identifiable weaknesses
38–50Uneven foundation; support will be needed
25–37Weak preparation for full HKDSE Physics
0–24Major foundational gaps across several topics
Mark weighting: Section A (25) + five structured questions (5 × 10 = 50) = 75 marks. Each topic carries 15 marks: 5 from True/False and 10 from the structured question.
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