Mark-by-Mark · Cambridge IGCSE Physics 0625

0625/22 May/Jun 2025: where students lost marks

The 7 questions the June 2025 examiners' report flagged on this paper. Full question, mark scheme, free. No sign-in needed.

Free: all 7 questions + mark schemes

Question 2

1 mark · Motion

The question

Where students lost marks

Nearly all stronger candidates described the ball as falling with constant acceleration, but a significant number of weaker candidates had the misconception that it would fall with increasing acceleration (D).

The trap: With no air resistance the only force is the weight, which is constant, so the acceleration is constant. The speed increases; the acceleration does not.

Source: Paper 0625/22 (Multiple Choice, Extended), Question 2, June 2025 examiners' report (paraphrased)

Mark scheme, mark by mark

B1Answer A: constant acceleration (g = 9.8 m/s²)

Teacher's note: Speed and acceleration are different things: a speed that keeps rising at the same rate is constant acceleration.

Question 6

1 mark · Forces

The question

Where students lost marks

Candidates found this very challenging; only the strongest gave the correct answer. Most took into account only the tension in the spring and not the weight of the mass, so the majority chose option B.

The trap: Resultant force = tension − weight = (30 × 0.12) − (0.15 × 9.8) = 3.6 − 1.47 = 2.13 N, so a = 2.13 ÷ 0.15 = 14 m/s². Tension alone gives B, 24 m/s².

Source: Paper 0625/22 (Multiple Choice, Extended), Question 6, June 2025 examiners' report (paraphrased)

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B1Answer A: 14 m/s² (resultant = 3.6 N − 1.47 N)

Teacher's note: Before any F = ma, list every force on the object. A hanging mass always has its weight.

Question 7

1 mark · Momentum

The question

Where students lost marks

Most stronger candidates calculated the change of momentum and the force correctly. The majority of weaker candidates chose option A, using only the momentum before the impact rather than the change of momentum.

The trap: The ball bounces back, so its velocity goes from +30 to −30 m/s: Δp = 0.15 × 60 = 9.0 kg m/s, and F = Δp ÷ Δt = 9.0 ÷ 1.0 × 10⁻³ = 9000 N.

Source: Paper 0625/22 (Multiple Choice, Extended), Question 7, June 2025 examiners' report (paraphrased)

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B1Answer D: Δp = 9.0 kg m/s, F = 9000 N

Teacher's note: Bounce = reversal: the change is twice the momentum. A stop would be once.

Question 24

1 mark · Sound

The question

Where students lost marks

Stronger candidates found the correct depth. Weaker candidates used the time for the pulse to travel to the seabed and back to the ship, which gives twice the depth, and chose option D.

The trap: 4.6 s is there and back. The pulse reaches the seabed in 2.3 s: depth = 1500 × 2.3 = 3450 m ≈ 3500 m. Using 4.6 s gives D, 6900 m.

Source: Paper 0625/22 (Multiple Choice, Extended), Question 24, June 2025 examiners' report (paraphrased)

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B1Answer C: 3500 m (1500 × 2.3)

Teacher's note: Every echo question: halve the time first.

Question 27

1 mark · Electric circuits

The question

Where students lost marks

Stronger candidates identified the change needed. Weaker candidates found it more challenging, with many suggesting connecting the ammeter in parallel with the lamp or swapping the positions of the ammeter and the voltmeter.

The trap: The ammeter is already right: in series. The voltmeter is the problem: it must be in parallel across the lamp. Then R = V ÷ I.

Source: Paper 0625/22 (Multiple Choice, Extended), Question 27, June 2025 examiners' report (paraphrased)

Mark scheme, mark by mark

B1Answer D: voltmeter in parallel with the lamp

Teacher's note: Ammeter in series, voltmeter in parallel. Always.

Question 30

1 mark · Electric circuits

The question

Where students lost marks

The majority of stronger candidates recalled that a diode is used to convert a.c. to d.c. Weaker candidates had the misconception that a transformer converts a.c. to d.c.

The trap: A transformer changes the size of an a.c. voltage; what comes out is still a.c. A diode lets current flow one way only, so it rectifies a.c. into d.c.

Source: Paper 0625/22 (Multiple Choice, Extended), Question 30, June 2025 examiners' report (paraphrased)

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B1Answer A: diode

Teacher's note: Transformer: bigger or smaller a.c. Diode: one direction. Rectifier = diode.

Question 37

1 mark · Radioactivity

The question

Where students lost marks

Nearly all stronger candidates applied half-life correctly, but the majority of weaker candidates had the misconception that once two half-lives had passed, all of the radioactive material would have decayed.

The trap: Each half-life halves what is left: 1 → ½ → ¼ → ⅛. After 60 minutes (three half-lives of 20 minutes) an eighth remains. It never reaches zero.

Source: Paper 0625/22 (Multiple Choice, Extended), Question 37, June 2025 examiners' report (paraphrased)

Mark scheme, mark by mark

B1Answer C: after 60 minutes, an eighth remains

Teacher's note: Two halves don't make a whole here: half of a half is a quarter, not zero.

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