All 51 questions from the West African Examinations Council (WAEC) Physics 2025 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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2025 WASSCE PHYSICS OBJECTIVE QUESTIONS
2025 WASSCE PHYSICS OBJECTIVE QUESTIONS
The diagram below illustrates a pulley system used to raise a 10kg load. If the effort F needed to raise the load is 70N, calculate the efficiency of the machine [g = 10 ms⁻²]
MA = Load/Effort = (10×10)/70 = 10/7. VR = number of pulleys/strings = 4. Efficiency = MA/VR × 100 = (10/7)/4 × 100 = 35.71%.
The diagram below illustrates the force-displacement of a body. Calculate the work done during the first 20m of motion.
Work done = area under the force-distance graph = area of trapezium + area of rectangle = ½(15+50)(20-10) + 50×10 = 325 + 500 = 825J.
The dispersion of light would result in which of the following phenomena?
Dispersion of white light into its component colours by water droplets produces a rainbow.
The best colour of shirt to be worn on a bright noon day is
White is a good reflector of radiation/heat, so it keeps the wearer cooler; black absorbs heat.
The image found when an object is placed between the focus and centre of a converging lens is
When an object is between F and 2F (or within focal length) of a converging lens, the image formed is erect, virtual and magnified.
For a charged body moving in an electric and magnetic crossed field, the ratio of the electric field intensity, E to the magnetic flux density, B is known as
In crossed E and B fields, only a charged particle with velocity v = E/B passes through undeflected — this ratio defines the velocity selector.
A note, K from a keyboard has an amplitude of 0.5 cm and frequency 2000 Hz. Another note, M from a guitar has an amplitude of 1.5 cm and frequency 2000 Hz. Which of the following statements is true if the two notes are compared?
Loudness depends on amplitude; M has a larger amplitude (1.5cm) than K (0.5cm), so M is louder. Same frequency means same pitch, but different instruments (sources) give different timbre.
A simple pendulum of length 0.8m is set oscillating on a planet. If the pendulum completes 20 oscillations in 60s, calculate the acceleration due to gravity on this planet. [π = 3.14]
T = t/n = 60/20 = 3s. T = 2π√(L/g) → g = 4π²L/T² = 0.8/0.2279 ≈ 3.51 ms⁻² ≈ 3.5 ms⁻².
A liquid of mass 2kg at 61°C is kept in a lagged vessel. If another 2kg of the same liquid at 21°C is added to the liquid in the vessel, calculate the final temperature of the mixture.
Heat lost by hot liquid = heat gained by cold liquid: mc(61-T) = mc(T-21) → 60-T = T-21 → 2T = 82 → T = 41°C.
The diagram below indicates the current induced in a coil as a result of relative motion between it and a bar magnet. Which of the diagrams illustrates the direction of the induced current?
By Lenz's law (the induced current opposes the change in flux producing it), the direction shown in option A is consistent with the relative motion of the magnet and coil.
If two bodies, A and B are each in thermal equilibrium with another body C, then the three bodies are in thermal equilibrium with each other. This is a statement of
This is the definition of the zeroth law of thermodynamics. The first law deals with energy conservation (ΔQ = ΔU + W); the second law deals with entropy and direction of heat flow.
A constant voltage source in the circuit below supplies a sinusoidal alternating e.m.f. The voltages marked against the components are the peak values. Determine the peak value of the applied e.m.f.
V = √(VR²+(VL-VC)²) = √(3²+(6-2)²) = √(9+16) = √25 = 5V (rms). Peak value V₀ = Vrms×√2 = 5×√2 = 7.1V.
A vibrator is used to generate ripples in a ripple tank. If the distance between two successive troughs is 3.5cm and the wave travels a distance of 31.5cm in 1.5s, calculate the frequency of the vibrator.
Speed v = distance/time = 31.5/1.5 = 21 cm/s = 0.21 m/s. λ = 3.5cm = 0.035m. f = v/λ = 0.21/0.035 = 6Hz.
The speed of light in medium A of refractive index 1.5 is 2.0×10⁸ ms⁻¹. Determine the speed of light in medium B of refractive index 1.2.
nₐvₐ = n_bv_b (since c = n×v is constant) → v_b = (nₐvₐ)/n_b = (1.5×2×10⁸)/1.2 = 2.5×10⁸ ms⁻¹.
The wavelength of a sound note travelling with a speed of 360 ms⁻¹ is 600m. Determine the period of the note.
f = v/λ = 360/600 = 0.6Hz. T = 1/f = 1/0.6 = 1.667s.
In which of the following levers is the effort applied between the load and the fulcrum?
Sugar tongs are third-class levers, in which the effort is applied between the fulcrum and the load.
Use the circuit diagram below to answer this question. The current passing through the 6Ω resistor is 1.5A. Calculate the current in the 3Ω resistor.
The 2Ω and 3Ω resistors are in parallel and share the total current of 1.5A. By the current-divider rule: I(3Ω) = R(2Ω)/(R(2Ω)+R(3Ω)) × I = 2/5 × 1.5 = 0.6A.
Use the circuit diagram to answer this question. Calculate the terminal p.d. of the battery in the diagram.
E.m.f. = IR, where I = 1.5A is the total current and R = 7.2Ω is the total external resistance. E.m.f. = 1.5×7.2 = 10.80V.
Which of the statements is correct about the nucleus of an atom? I. It is centrally located in the atom II. It contains the nucleons and electrons III. It is positively charged due to the protons IV. It decays when there is instability inside
The nucleus is centrally located in the atom, is positively charged due to the protons, and an unstable nucleus undergoes radioactive disintegration to become more stable. (Statement II is false — electrons orbit outside the nucleus.)
A radioactive element of mass 16g was isolated and stored. It was discovered that after 40 days only 1g of the element remained undecayed. Calculate the half-life of the element.
16g → 8g → 4g → 2g → 1g represents 4 half-lives. T½ = t/n = 40/4 = 10 days.
Which of the following reasons explains why the walls and ceilings of a standard concert hall are usually covered with perforated pads?
Perforated acoustic pads absorb sound energy and reduce multiple reflections, thereby reducing reverberation.
A bucket of water of mass 10kg is swung in a vertical circle of radius 1.2m. While at the lowest position of the swing, its speed is 5 ms⁻¹. Determine the tension in the string. [g = 10 ms⁻²]
At the lowest point, T = mg + mv²/r = (10×10) + (10×5²)/1.2 = 100 + 250/1.2 = 100 + 208.3 = 308.3N.
A man's near point is 30cm. Which of the following eye defects is the man likely to suffer from?
A near point greater than the normal 25cm indicates long-sightedness (hypermetropia) — the person cannot see nearby objects clearly.
White light can be produced by a combination of I. magenta, yellow and cyan II. red, blue and green III. magenta and green IV. yellow, red and green
Combining Magenta+Yellow+Cyan = White (I); Red+Blue+Green = White (II); Magenta+Green = White (III). Statement IV does not give white light.
The diagram below shows a beam of light incident on a mirror. Such a mirror can be used as
A convex (diverging) mirror gives a wide field of view and is used as a rear-view/surveillance mirror in vehicles, shops, banks, and supermarkets.
Which of the following statements about a stationary wave is NOT true?
In a stationary wave, particles between two adjacent nodes vibrate IN phase (move together in the same direction at the same time), so statement A is the false (not true) statement.
In a pipe closed at one end and open at the other end, the overtones that accompany the fundamental frequency are
A pipe closed at one end produces only odd harmonics: f₀, 3f₀, 5f₀, 7f₀, ...
A radioactive substance of mass 512.0g decays to 64.0g. Determine the number of half-lives involved in the decay.
512g → 256g → 128g → 64g corresponds to 3 half-lives, since (1/2)³ = 64/512 = 1/8.
Two waves will interfere destructively if the path difference between the waves is
Destructive interference occurs at path differences of (n+½)λ; the minimum condition (n=0) gives a path difference of λ/2 (half a wavelength).
Which of the following statements about a step-up transformer is correct?
For a step-up transformer, Ns > Np and Vs > Vp, meaning the primary coil has fewer turns than the secondary coil.
The unit of magnetic flux density is
Magnetic flux density B = Magnetic flux/Area (Wb/m²), which is measured in Tesla.
Meters are installed in houses to monitor and evaluate the cost of the electricity consumed. What physical quantity does this meter measure?
Household electricity meters measure the total energy consumed (in kWh), not just the instantaneous power.
The type of energy stored by a dry Leclanché cell is
A dry cell stores chemical energy, which is converted into electrical energy when the cell is in use.
The microphone transforms energy from
A microphone converts sound energy (mechanical vibrations of air) into an electrical signal.
A hospital received 16g of a radioactive substance at 1300 hour GMT. At 1700 hour GMT, the fraction of the substance left undecayed was 1/16. Determine the half-life of the substance.
Time elapsed = 1700-1300 = 4hrs. 1/16 = (1/2)ⁿ → n = 4 half-lives. T½ = t/n = 4/4 = 1 hour.
Which of the following situations pertains to Newton's third law of motion?
A rocket is propelled forward by expelling exhaust gases backward — an action-reaction pair, illustrating Newton's third law.
The force and velocity of a system are each reduced simultaneously by one-half. The power of the system is
P = F×V. Halving both F and V gives P' = (F/2)×(V/2) = FV/4, i.e. power is reduced to a quarter of its original value.
A plane is inclined at 45° to the horizontal. Calculate the velocity ratio of the plane.
For an inclined plane, VR = 1/sinθ = 1/sin45° = 1/0.707 = √2 ≈ 1.41.
A body in a lift is moving down with acceleration equal to acceleration due to gravity. Which of the following statements is correct?
A body accelerating downward at g is in free fall, and a body in free fall experiences apparent weightlessness.
When the pressure in oil is increased, the viscosity of the oil would be
Increasing pressure in a liquid forces its molecules closer together, increasing resistance to flow, i.e. increasing viscosity.
What is the number of neutrons in ¹⁴₆C?
Number of neutrons = mass number − atomic (proton) number = 14 − 6 = 8.
The ice and steam points of a resistance thermometer are 12.0Ω and 20.0Ω respectively. Calculate the resistance of the thermometer at 10°C.
By linear interpolation: R = 12 + (10/100)×(20-12) = 12 + 0.8 = 12.8Ω.
A radium nuclide decays by emitting alpha particles as shown below: ²²⁶₈₈Ra → X + ⁴₂He. Determine the daughter nuclide.
By conservation of mass number: 226 = a+4 → a = 222. By conservation of atomic number: 88 = b+2 → b = 86. Daughter nuclide is ²²²₈₆X.
A bullet of mass 0.025kg moves at 250 ms⁻¹. Calculate its de Broglie wavelength. [h = 6.67×10⁻³⁴ Js]
λ = h/(mv) = 6.67×10⁻³⁴/(0.025×250) = 6.67×10⁻³⁴/6.25 = 1.067×10⁻³⁴ m.
An electron moving with a speed of 5.0×10⁵ ms⁻¹ enters a uniform magnetic field at 90°. Calculate the magnitude of the magnetic force on the electron if the magnetic field intensity is 0.25T. [e = 1.6×10⁻¹⁹C]
F = qvB sinθ; sin90° = 1. F = 1.6×10⁻¹⁹×5×10⁵×0.25 = 2.0×10⁻¹⁴N.
A beam of light which appears to come from a point in space is said to be
Light rays that spread outward as if originating from a point source form a divergent beam.
A sound wave made up of a large number of unrelated frequencies superimposed on each other is called
A jumble of unrelated frequencies superimposed together, with no clear pattern, is called noise.
A boy pushes a box of mass 80kg along a horizontal floor with a force of 200N. If the box is pushed with a uniform velocity, what is the coefficient of friction between the box and the floor? [g = 10 ms⁻²]
Uniform velocity means net force = 0, so the applied force equals the frictional force: F = Fr = μmg. μ = F/(mg) = 200/(80×10) = 200/800 = 0.25.
Extremely thin wires can be drawn from platinum simply because platinum is
Ductility is the property that allows a material to be drawn into thin wires; platinum is highly ductile.
The S.I unit of inductance is
The SI unit of inductance is the Henry (H).
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