CIE iGCSE Physics Paper 4 Prediction - 2025

CIE iGCSE Physics Paper 4 Prediction – 2025

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Questions 1

A load is suspended from a thread. The vertical force on the thread due to the load is 0.75N.
(a) Calculate the mass of the load.

(b) Fig. 1.1 shows the load suspended from the thread.A wire is attached to the load at point X and pulled horizontally to the right. The tension in the horizontal wire is 1.2N. By drawing a scale diagram or by calculation, determine:
• the magnitude of the resultant of the force at X due to the load and due to the tension in the wire
• the direction of the resultant relative to the vertical direction. Show your working.

▶️Answer/Explanation

(a) 0.077 kg OR 77 g

g =W / m OR (m =)W / g OR 0.75 / 9.8

(b)

1.4 (N)
58(°)

 velocity
 speed
 direction
 acceleration / deceleration
 moment

Questions 2

Fig. 3.1 shows two children balanced on a seesaw. A seesaw is a length of wood which rotates about a central pivot.

(a) Child B moves 0.050m further away from the pivot.
(i) Explain why the seesaw rotates clockwise.

(ii) Child A puts on a backpack and the seesaw now balances. Calculate the mass of the backpack.

(b) The concrete floor under the seesaw is replaced with a rubber floor. A child falls from the seesaw and experiences an impulse when they hit the floor.
(i) Define impulse.

(ii) Explain how the rubber floor reduces injury to the child. Use ideas about impulse, force, momentum and time in your answer.

▶️Answer/Explanation

(a) (i) clockwise moment has increased (and no change to anti-clockwise moment)

(ii) (mass of backpack =) 45 / \((1.6\times 9.8))\) 2.9 (kg)
(at balance) sum of clockwise moments = sum of anti-clockwise moments OR \((900\times 0.85)\) = \(1.6\times (450 +W)\)
(clockwise moment =) 765 (N m) OR (moment due to backpack =) 45 (N m) OR (W =) [{\(900\times 0.85\)} – {\(450\times 1.6\)}] / 1.6

(b)(i) (impulse is the) force × time (for which the force acts) OR I = F × t OR (impulse =) change in momentum OR ∆{mv}

(ii) any three from:
 change in momentum/impulse is the same (on both floors)
 (change in momentum/Impulse) is over longer time
 force = rate of change of momentum OR F = \(\Delta {mv}/\Delta t\)
 less force on child (so less injury)

Question 3

(a) State the name that is given to the turning effect of a force.

…………………………………………………………………………………………………………………….. [1]

(b) A gate has rusty hinges that are very stiff. A man opens the gate by pulling on it, as shown in Fig. 1.1.

After he has passed through the opening, he closes the gate behind him.

When closing the gate, the man pulls it at a point halfway along its length.

State two differences between his force when closing the gate and his force when

he opened the gate.

1. ……………………………………………………………………………………………………………………..

2. ……………………………………………………………………………………………………………………..[2]

…………………………………………………………………………………………………………………….. [1] [Total: 4]

Answer/Explanation

Ans: (a) moment/torque ignore turning force

(b) opposite direction condone different direction(s) larger or correct reverse argument (opening force is smaller)

(c) (apply) force further from hinge OR oil/reduce friction/new hinge/use an assist mechanism/replace hinge(s)

Questions 4

Fig. 4.1 shows a stainless-steel saucepan being heated on an electric cooker. The saucepan contains water.

(a) State what happens to the water particles as the water temperature increases.
(b) The saucepan contains \(250cm^3\) of water. The specific heat capacity of water is 4200J/(kg°C). The density of water is 1000 \(kg/m^3\).
(i) Show that the mass of the water in the saucepan is 0.25kg.

(ii) Calculate the energy required to increase the water temperature from 20°C to 65°C.

(iii) The heater supplies enough power to heat the water in 39s. A student measures the time taken to heat the water as 115s. Suggest why the actual time taken to heat the water is longer. Assume that the student takes accurate measurements.

(c) The stainless-steel saucepan is replaced with an aluminium saucepan of the same mass. It contains the same volume of water.
The specific heat capacity of stainless steel is 500J/(kg°C).
The specific heat capacity of aluminium is 890J/(kg°C).
Explain how using an aluminium saucepan will affect the time taken to heat the water.

▶️Answer/Explanation

(a) (average) KE of particles increases / particles move faster

(b)(i) \(\rho \) = m / v OR (m =) \(\rho v\)

\(1 cm^3\) = \(1\times 10^{–6}m^3\) OR \(250 cm^3\) = \(2.5\times 10^{–4} m^3\) OR \(1000 \times 2.5 \times 10^{–4}\) (= 0.25 kg)

(ii) 47000 J
\((\Delta \theta =)\) 65 – 20 °C OR \((\Delta \theta =)\) 45 °C
E = mc\(\Delta \theta \) OR (E =) mc \(\Delta \theta \) OR (E =) \(0.25\times 4200\times 45\)

(iii) thermal energy also transferred to the pan / surroundings OR thermal energy escapes from the water (as it is being heated)

(c) any two from:
 (aluminium saucepan) takes longer to heat the water
 more (thermal) energy is needed (with aluminium pan for the same increase in temperature)
 (because aluminium) has a higher specific heat capacity

Questions 5

(a) A sound wave travels through air. Fig. 6.1 shows a pressure–time graph for the air at one place.

(i) On Fig. 6.1:
• label one point C to indicate a compression
• label one point R to indicate a rarefaction.

(ii) Explain why this graph cannot be used to find the wavelength of the sound wave.

(iii) The sound becomes louder and of lower pitch. State what happens to:
the amplitude of the sound
the frequency of the sound

(b) A sound of frequency 13kHz is transmitted through water. The speed of sound in water is 1500m/ s. Calculate the wavelength of this sound in water.

▶️Answer/Explanation

(a) (i) C marked and labelled at a peak of the sine wave
R marked and labelled at a trough of the sine wave

(ii) graph / it does not show (variation with) displacement

(iii) (amplitude) increases AND (frequency) decreases

(b) 0.12 m
v = f \(\lambda \) OR \((\lambda =)\)v / f OR \((\lambda )\) = 1500 / 13 000
1500 / 13 000 OR \(1.2\times 10^N\)

Questions 6

Fig. 7.1 shows two charged metal plates. X marks the position of the centre of the space between the plates.

(a) (i) On Fig. 7.1, draw at least four field lines to show the pattern and the direction of the electric field between the two charged plates.
(ii) Describe the effect on a negatively charged particle placed at X.

(b) During a thunderstorm, an electric field is set up between a cloud and the ground. Charges on the cloud and on the ground are shown in Fig. 7.2.

The lightning shown in Fig. 7.2 discharges a current of 28000A for 0.0012s.

(i) Calculate the charge that flows from the cloud to the ground.

(ii) The lightning transfers \(1.2 × 10^8\) J of energy. Calculate the potential difference between the base of the cloud and the ground.

▶️Answer/Explanation

(a) (i) evenly spaced straight vertical lines from one plate to the other arrows on lines pointing towards negatively charged plate

(ii) (negatively charged particle has) force / attraction towards positively charged / positive (plate)

(b)(i) 34 C
I = Q / t OR (Q =)It OR \(28 000\times 0.0012\)

(ii) (p.d. =) 3.6 MV OR \(3.6\times 10^6\) V
E = ItV OR (V =) E/ It OR (V =) E / Q OR (V =) \(1.2\times 10^8\) / 34

Questions 7

(a) Fig. 7.1 shows three bars of steel, A, B and C.

A student is given the three pieces of steel. Two of the pieces are magnetised and one piece is unmagnetised. Describe and explain how the student determines which piece is unmagnetised using only the three pieces of steel.

(b) Fig. 7.2 shows a circuit diagram of a step‑down transformer.

(i) The mains voltage supplied to the transformer is 240V. The output power of the transformer is 45W. The transformer is 100% efficient. Calculate the input current to the transformer.

(ii) Draw a labelled diagram of a step‑down transformer. On the labels, state a suitable material for each of the components.

▶️Answer/Explanation

(a) (end of) one piece of steel brought close to (the end of) another piece owtte
look to see if there is repulsion/attraction AND test between different ends/poles owtte
any two from:

 repeat a valid test between the other pieces
 only magnets repel each other OR the pieces that repel are magnets
 attractions at both ends indicates one of them is unmagnetised
OR the piece that only attracts is unmagnetised
OR the piece that does not repel (at both ends) is unmagnetised

(b)(i) 0.19 A
\(I_p V_p = I_s V_s\) OR \((I_p =) I_s V_s / V_p\) OR \((I_p =)\) 45 / 240 OR \(I_p V_p \)= 45 OR power in primary = power in secondary
\((I_p= )\) 45 / 240

(ii) labelled diagram showing:
 (soft) iron core
 copper (coils)
 primary and secondary (coils) labelled AND fewer coils on secondary than on primary

Questions 8

(a) An experiment directs alpha particles at a very thin sheet of gold foil.
(i) Most of the alpha particles pass through the thin foil in a straight line. State the conclusion about atoms from this observation.
(ii) Some of the alpha particles are deflected through angles less than 90° and a few are deflected through 180°. State and explain two conclusions about the nuclei of atoms from this observation.
(b) A source contains a radioactive isotope of strontium. This isotope decays by emission of β‑particles. The half‑life of this isotope is 29 years.
(i) State the change in the nucleus which occurs when a β‑particle is emitted.
(ii) The initial mass of this isotope of strontium in the source is 25µg. Calculate the mass of the strontium isotope that decays in 87 years.

▶️Answer/Explanation

Ans

(a)(i) most of the atom is empty space

(ii) any two from:
1 the nucleus is very small
2 mass of gold nucleus is much greater than mass of alpha particle
3 the nucleus is positively charged
corresponding explanation to conclusion:
1 not many alpha particles pass close to the nucleus / owtte
2 large force between alpha and nucleus (has bigger effect on small mass of alpha)
3 alpha particles are positively charged, AND force is repulsive

(b)(i) (in the nucleus a) neutron is changed into a proton (and an electron which is the emitted β-particle)

(ii) \(22 \mu \times g\)
(87 years is) three half-lives OR 25 / 8 OR 87 / 29 = 3 (half lives)
1 / 8th (of the strontium remains) OR 25 / 8 (decays) OR 3.125 seen

Question 9

Fig. 10.1 represents a neutral atom of an isotope of element X.

(a) State one similarity between this atom and a neutral atom of a different isotope of element X.

(b) The isotope of element X is radioactive. It decays to form an isotope of element Y by emitting a β-particle.
(i)Using Fig. 10.1 deduce the nuclide notation for the isotope of Y produced by this decay.
nuclide notation:(ii) β-particles ionise the air they pass through less strongly than the same number of α-particles.
Suggest why this is so.

Answer/Explanation

Answer:

(a) equal number of electrons OR equal number of protons

(b) (i) \(^{13}_5\)X
\(^0_{-1}\)β
\(^{13}_6\)Y

(b) (ii) any three from:
• β-particles have charge of smaller size
• β-particles have smaller mass
• β-particles have less energy
• β-particles travel faster / less time near to air molecule
• effect / force on electrons in air molecules less

CIE iGCSE Physics Paper 4 Prediction

CIE iGCSE Physics Paper 4 Prediction - 2025