WAEC Physics 1996 past questions

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

Ten questions from the 1996 WAEC Physics paper, with answers and explanations. We hold 38 questions from this paper, and the Skolra app has all of them.

WAEC Physics 1996 questions and answers

1. 1.a ball of mass 5.0kg hits a smooth vertical wall normally with a speed of 2m^-1 and rebounds with the same speed. Determine the impulse experienced by the ball
   1. A
      20 Ns
      Correct
   2. B
      5 Ns
   3. C
      40 Ns
   4. D
      10 Ns
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   Answer: A

   Impulse equals the change in momentum of the ball.

   Taking the direction toward the wall as positive, the ball's velocity changes from +2 ms⁻¹ to −2 ms⁻¹ on rebound.

   Impulse = m(v − u) = 5.0 × (−2 − 2) = 5.0 × (−4) = −20 Ns

   The magnitude of the impulse is 20 Ns.

2. 2.What is the decay constant of a radioactive element whose half-life is 3 seconds
   1. A
      0.231 s⁻¹
      Correct
   2. B
      2.079 s⁻¹
   3. C
      0.462 s⁻¹
   4. D
      0.347 s⁻¹
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   Answer: A

   The decay constant λ is related to the half-life t_½ by:

   λ = ln 2 / t_½ = 0.6931 / 3 s ≈ 0.231 s⁻¹.

   This means that per second, approximately 23.1% of the remaining nuclei decay.

3. 3.Lenz's law of electromagnetic induction states that
   1. A
      the induced current is proportional to the resistance of the circuit
   2. B
      the magnitude of induced emf is proportional to the rate of change of magnetic flux linkage
   3. C
      an emf is induced whenever a conductor is placed in a magnetic field
   4. D
      the induced emf acts in a direction that opposes the change in flux producing it
      Correct
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   Answer: D

   Lenz's law states that the direction of an induced electromotive force (and hence the induced current) is always such that it opposes the change in magnetic flux that caused it. This is a consequence of the law of conservation of energy. Option B describes Faraday's law (the magnitude), not Lenz's law (the direction).

4. 4.A wire of length 100cm and cross-sectional area of 2.0 x 10^-3cm² has a resistance of 0.10 Ω. Calculate its electrical conductivity.
   1. A
      5.0 × 10⁸ Sm⁻¹
   2. B
      5.0 × 10⁶ Sm⁻¹
   3. C
      5.0 × 10⁷ Sm⁻¹
      Correct
   4. D
      5.0 × 10⁵ Sm⁻¹
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   Answer: C

   Convert units: L = 1.00 m; A = 2.0 × 10⁻³ cm² = 2.0 × 10⁻⁷ m²; R = 0.10 Ω.

   Resistivity: ρ = RA/L = (0.10 × 2.0 × 10⁻⁷) / 1.0 = 2.0 × 10⁻⁸ Ω m.

   Conductivity σ = 1/ρ = 1 / (2.0 × 10⁻⁸) = 5.0 × 10⁷ Sm⁻¹.

5. 5.The linear expansivity of a metal P is twice that of another metal Q. When these materials are heated through the same temperature change, their increase in length is the same. Calculate the ratio of the original length of P to that of Q.
   1. A
      1 : 4
   2. B
      2 : 1
   3. C
      4 : 1
   4. D
      1 : 2
      Correct
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   Answer: D

   Linear expansion: ΔL = αL₀ΔT.

   Given α_P = 2α_Q, and ΔL_P = ΔL_Q, ΔT is the same for both:

   2α_Q × L_P × ΔT = α_Q × L_Q × ΔT

   Dividing both sides: 2L_P = L_Q, so L_P : L_Q = 1 : 2.

6. 6.The heating element in an electric kettle is usually located near the bottom of the kettle because
   1. A
      the electric resistance of the element is greatest at the bottom
   2. B
      conduction is faster through the base of the kettle
   3. C
      radiation transfers heat more efficiently from the bottom
   4. D
      convection currents set up in the water circulate it and heat the whole volume uniformly
      Correct
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   Answer: D

   In liquids, the primary mode of heat transfer is convection. When the heating element is at the bottom, the water in contact with it becomes less dense and rises, while cooler, denser water sinks to replace it. This sets up convection currents that circulate throughout the water, ensuring the entire volume is heated uniformly and efficiently.

7. 7.Which of the following statements is not correct? Isotopes of an element have
   1. A
      the same atomic number
   2. B
      the same number of protons in the nucleus
   3. C
      the same number of electrons when neutral
   4. D
      the same number of neutrons in the nucleus
      Correct
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   Answer: D

   Isotopes of an element are atoms with the same atomic number (same number of protons) but different mass numbers (different number of neutrons). Because they have the same number of protons, neutral atoms of isotopes also have the same number of electrons. The statement that is not correct is that isotopes have the same number of neutrons — it is precisely the differing neutron count that distinguishes one isotope from another.

8. 8.A 400W immersion heater is used to heat a liquid of mass 0.5kg. If the temperature of the liquid increases by 2.5^oC in one second, calculate the specific heat capacity of the liquid (Neglect heat losses to the surroundings)
   1. A
      640 Jkg⁻¹K⁻¹
   2. B
      500 Jkg⁻¹K⁻¹
   3. C
      320 Jkg⁻¹K⁻¹
      Correct
   4. D
      160 Jkg⁻¹K⁻¹
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   Answer: C

   Power = rate of heat transfer, so in 1 second: Q = Pt = 400 × 1 = 400 J.

   Using Q = mcΔT:

   c = Q / (mΔT) = 400 / (0.5 × 2.5) = 400 / 1.25 = 320 Jkg⁻¹K⁻¹

9. 9.Which of the following particles/rays do not originate from the nucleus of an atom?
   1. A
      Alpha particles
   2. B
      Gamma rays
   3. C
      X-rays
      Correct
   4. D
      Beta particles
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   Answer: C

   Alpha particles (helium nuclei), beta particles (electrons/positrons from nuclear beta decay), and gamma rays all originate from changes within the atomic nucleus.

   X-rays, however, originate outside the nucleus — they are produced when fast-moving electrons decelerate in a target material (Bremsstrahlung) or when orbital electrons in an atom fall to a lower energy level. They are therefore not nuclear in origin.

10. 10.Cloud formation is the direct result of
    1. A
       condensation of water vapour at high altitudes
       Correct
    2. B
       convection currents near the ground
    3. C
       radiation of heat from the earth's surface
    4. D
       evaporation of water from the ocean surface
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    Answer: A

    Clouds form when moist warm air rises, expands, and cools to below its dew point. At that point, water vapour condenses onto tiny dust or aerosol particles (condensation nuclei) to form tiny water droplets or ice crystals that collectively make up a cloud. Cloud formation is therefore the direct result of condensation of water vapour at altitude.

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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