WAEC Physics 2006 past questions
Ten questions from the 2006 WAEC Physics paper, with answers and explanations. We hold 47 questions from this paper, and the Skolra app has all of them.
WAEC Physics 2006 questions and answers
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1.In which of the following media would sound wave travel fastest?
- AVacuum
- BAir
- CWater
- DSteelCorrect
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Answer: D
The speed of sound increases with the rigidity and density of the medium: it is greatest in solids, less in liquids, and least in gases. Sound cannot travel in a vacuum.
- Air ≈ 340 m s−1
- Water ≈ 1500 m s−1
- Steel ≈ 5100 m s−1
Therefore sound travels fastest in steel.
- A
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2.A ray from a fixed object is incident on a plane mirror at an angle of 20o. If the mirror is rotated through 30o by how many degree would the reflected ray rotate?
- A80°
- B20°
- C60°Correct
- D30°
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Answer: C
When a plane mirror is rotated by an angle θ, the reflected ray rotates by 2θ (since both the angle of incidence and the normal rotate, doubling the deviation).
Mirror rotation = 30°, so the reflected ray rotates by 2 × 30° = 60°.
- A
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3.Which of the following physical processes cannot be explained by the molecular theory of matter?
- ARadioactivityCorrect
- BDiffusion of gases
- CSurface tension of liquids
- DOsmosis
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Answer: A
The molecular theory of matter explains phenomena that arise from the behaviour and interaction of molecules — such as diffusion, surface tension, osmosis, and Brownian motion.
Radioactivity is a nuclear phenomenon involving changes within the atomic nucleus (emission of alpha, beta or gamma radiation). It has nothing to do with intermolecular forces or molecular motion, so it cannot be explained by the molecular theory of matter.
- A
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4.The distance between the successive crests of a wave travelling at 20ms-1 is 25cm. Calculate the frequency of the wave
- A5 Hz
- B500 Hz
- C20 Hz
- D80 HzCorrect
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Answer: D
The distance between successive crests is the wavelength: λ = 25 cm = 0.25 m.
Using the wave equation v = fλ:
f = v / λ = 20 / 0.25 = 80 Hz
- A
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5.The potential energy in an elastic string of force constant K which has been extended by X metres is expresses as
- A2KX²
- BKX²
- CKX
- D½KX²Correct
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Answer: D
The elastic potential energy stored in a spring or elastic string obeying Hooke's law is:
PE = ½KX²
where K is the force constant (N m−1) and X is the extension (m). This formula comes from integrating the force F = KX over the extension: PE = ∫₀ˣ Kx dx = ½KX².
- A
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6.The sagging of overhead electrical cables is the consequence of
- Areduction in the load carried by the cables
- Blinear expansion of the cables when temperature increasesCorrect
- Ccontraction of the cables in cold weather
- Ddecrease in the voltage of the electrical supply
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Answer: B
Overhead electrical cables are made of metal (aluminium or copper), which undergoes linear thermal expansion when the temperature rises.
On hot days the cables expand, increasing their length and causing them to sag. Cables are deliberately installed with a certain amount of slack to accommodate this expansion safely and to prevent snapping from contraction in cold weather.
- A
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7.Which of the following factors does not affect the capacitance of a parallel plate capacitor?
- ADistance between the plates
- BNature of the dielectric medium between the plates
- CArea of the plates
- DMaterial of the platesCorrect
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Answer: D
The capacitance of a parallel plate capacitor is given by:
C = ε0εrA / d
where A is the area of the plates, d is the separation, and εr is the relative permittivity of the dielectric. The material of the plates (e.g., copper vs. aluminium) does not appear in this formula and therefore does not affect capacitance.
- A
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8.A quantity of steam at 100oC condenses to water at the same temperature by releasing 6.9 x 104J of energy. Calculate the mass of the condensed steam. [specific latent heat of vaporization of eater = 2.3 x 106 J kg-1]
- A0.03 kgCorrect
- B0.10 kg
- C0.01 kg
- D0.30 kg
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Answer: A
Using Q = mL, where L is the specific latent heat of vaporization:
m = Q / L = (6.9 × 104) / (2.3 × 106)
m = 3 × 10−2 kg = 0.03 kg
- A
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9.A stone of mass 2.0kg is thrown vertically upward with a velocity of 20.0 ms-1, calculate the initial kinetic energy of the stone
- A400 JCorrect
- B800 J
- C200 J
- D40 J
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Answer: A
The initial kinetic energy is:
KE = ½mv²
KE = ½ × 2.0 × (20.0)² = ½ × 2 × 400 = 400 J
- A
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10.A solid body will float in a liquid if its
- Aweight equals the upthrust on itCorrect
- Bvolume is less than the volume of the container
- Cweight is greater than the upthrust on it
- Ddensity is greater than that of the liquid
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Answer: A
A solid body floats in a liquid when the upthrust (buoyant force) equals its weight.
By Archimedes' principle, the upthrust equals the weight of liquid displaced. When the body floats, it displaces exactly enough liquid so that this upthrust balances its weight. If the upthrust were less than the weight the body would sink, and if greater it would rise further out of the liquid.
- A
The questions come from past JAMB, WAEC and NECO papers. We use software to help write the answer options and explanations, and every answer is checked twice before it goes on the site. How we check
Spotted a wrong answer? Tell us from the app or on the contact page and we check it.
Practise all 47 questions we hold from the 2006 paper, on a timed CBT screen
Every question has the answer and an explanation, in the Skolra app.