WAEC Physics 2012 past questions

Checked by the Skolra question team · Last updated 15 October 2026

Ten questions from the 2012 WAEC Physics paper, with answers and explanations. We hold 50 questions from this paper, and the Skolra app has all of them.

WAEC Physics 2012 questions and answers

1. 1.When two waves are superimposed on each other, the following occurrences are possible, except
   1. A
      refraction
      Correct
   2. B
      destructive interference
   3. C
      constructive interference
   4. D
      beats
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   Answer: A

   Refraction is not a result of superposition; it occurs when a wave passes from one medium to another of different optical density, changing its speed and direction. Constructive interference, destructive interference, and beats are all direct consequences of the superposition principle.

2. 2.A girl stands on a scale in a lift. If the reading on the scale is less than her weight, then the lift is moving
   1. A
      upward with uniform acceleration
   2. B
      upward at constant velocity
   3. C
      downward at constant velocity
   4. D
      downward with uniform acceleration
      Correct
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   Answer: D

   When a lift accelerates downward, the normal reaction N on the girl is reduced. By Newton's 2nd law:

   N = m(g − a)

   Since (g − a) < g, the scale reading N is less than the true weight mg. At constant velocity (up or down), a = 0 and N = mg, so the reading equals her weight.

3. 3.A block of wood of density 0.6 gcm^-3, weighing 3.06N in air, floats freely in a liquid of density 0.9 gcm^-3. Calculate volume of the portion immersed (g = 10ms^-2)
   1. A
      510 cm³
   2. B
      340 cm³
      Correct
   3. C
      170 cm³
   4. D
      255 cm³
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   Answer: B

   Mass of wood = W/g = 3.06/10 = 0.306 kg = 306 g

   Volume of wood = mass/density = 306/0.6 = 510 cm³

   For a floating body: weight = weight of liquid displaced

   Fraction immersed = ρ_wood/ρ_liquid = 0.6/0.9 = 2/3

   V_immersed = (2/3) × 510 = 340 cm³

4. 4.The sound heard by a person after the reflection of the sound generated by him is called
   1. A
      diffraction
   2. B
      echo
      Correct
   3. C
      reverberation
   4. D
      resonance
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   Answer: B

   An echo is the distinct repetition of a sound heard by a person after it has been reflected from a surface (such as a cliff or wall). For an echo to be heard distinctly, the reflecting surface must be at least about 17 m away so the reflected sound arrives more than 0.1 s after the original.

5. 5.The time of flight for a projectile motion is given by the expression
   1. A
      T = 2u sin θ / g
      Correct
   2. B
      T = u sin θ / g
   3. C
      T = 2u cos θ / g
   4. D
      T = u cos θ / g
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   Answer: A

   For a projectile launched at initial speed u and angle θ to the horizontal, the vertical component is u sin θ.

   Time to reach maximum height: t = u sin θ / g

   Total time of flight: T = 2u sin θ / g (the factor 2 accounts for the symmetric return journey).

6. 6.Which of the following properties of waves is exclusive to transverse waves?
   1. A
      polarization
      Correct
   2. B
      diffraction
   3. C
      refraction
   4. D
      reflection
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   Answer: A

   Polarization is the property exclusive to transverse waves. It restricts the oscillation of the wave to a single plane perpendicular to the direction of propagation. Longitudinal waves (e.g. sound) cannot be polarized because their oscillations are parallel to the direction of travel. Reflection, diffraction, and refraction occur for both transverse and longitudinal waves.

7. 7.Which of the following arrangements of radiations is in the order of decreasing penetrating power?
   1. A
      β, α, γ
   2. B
      γ, β, α
      Correct
   3. C
      α, γ, β
   4. D
      α, β, γ
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   Answer: B

   In decreasing order of penetrating power:
   γ (gamma) → β (beta) → α (alpha)

   • Gamma rays: electromagnetic radiation; can penetrate several centimetres of lead or metres of concrete.
   • Beta particles: stopped by a few millimetres of aluminium.
   • Alpha particles: stopped by a sheet of paper or a few centimetres of air.

   Alpha particles lose energy quickly due to their large charge and mass.

8. 8.a bird flies at 10ms^-1 for 3s, 15ms^-1 for 3s and 20 ms^-1 for 4s. Calculate the bird's average speed
   1. A
      16.5 ms⁻¹
   2. B
      15.0 ms⁻¹
   3. C
      14.5 ms⁻¹
   4. D
      15.5 ms⁻¹
      Correct
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   Answer: D

   Average speed = Total distance ÷ Total time

   Total distance = (10 × 3) + (15 × 3) + (20 × 4) = 30 + 45 + 80 = 155 m

   Total time = 3 + 3 + 4 = 10 s

   Average speed = 155 ÷ 10 = 15.5 ms⁻¹

9. 9.Six dry cells each of e.m.f. 2.0 and internal resistance of 1.0$\Omega$ are connected in parallel across a load of 3.0$\Omega$. Calculate the effective current in the circuit
   1. A
      4.00 A
   2. B
      1.05 A
   3. C
      0.63 A
      Correct
   4. D
      2.00 A
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   Answer: C

   For identical cells in parallel: equivalent EMF = 2.0 V; equivalent internal resistance = r/n = 1.0/6 Ω

   Total resistance = R_load + r_eff = 3.0 + 1/6 = 19/6 Ω

   I = EMF / R_total = 2.0 / (19/6) = 12/19 ≈ 0.63 A

10. 10.An atom in an excited state is one whose
    1. A
       electrons have moved to higher energy levels by absorbing energy
       Correct
    2. B
       nucleus has gained extra neutrons from the environment
    3. C
       electrons have permanently escaped from the atom
    4. D
       nucleus has lost some protons to become more stable
    Show answerHide answer

    Answer: A

    An atom is in an excited state when one or more of its electrons have absorbed energy and jumped from a lower energy level to a higher energy level (a level further from the nucleus). The atom is unstable in this state and will return to the ground state by emitting the absorbed energy as a photon of electromagnetic radiation (e.g., visible light, UV or X-rays), a process known as emission.

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

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