WAEC Physics 1994 past questions

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

Ten questions from the 1994 WAEC Physics paper, with answers and explanations. We hold 38 questions from this paper, and the Skolra app has all of them.

WAEC Physics 1994 questions and answers

1. 1.Which of the following substances is not an insulator?
   1. A
      silicon
      Correct
   2. B
      rubber
   3. C
      glass
   4. D
      ebonite
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   Answer: A

   Silicon is a semiconductor — it conducts electricity under certain conditions and is not an insulator.

   Glass, ebonite, and rubber are all good insulators that do not allow the flow of electric current under normal conditions.

2. 2.500g of water is heated so that its temperature rises from 30°C to 72°C in 7 minutes. calculate the supplied per minute. (Specific heat capacity of water is 4200J kg⁻¹K⁻¹)
   1. A
      88,200 J/min
   2. B
      9,000 J/min
   3. C
      12,600 J/min
      Correct
   4. D
      6,300 J/min
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   Answer: C

   Total heat supplied: Q = mcΔT = 0.5 × 4200 × (72 − 30) = 0.5 × 4200 × 42 = 88,200 J

   Heat per minute = 88,200 / 7 = 12,600 J/min

3. 3.The wave function of a metal is 8.0 x 10⁻¹⁹J. Calculate the wavelength of its threshold frequency. (Speed of light in a vacuum = 3 x 10⁸ms⁻¹, Planck's constant = 6.6 × 10⁻³⁴Js)
   1. A
      2.5 × 10⁻⁷ m
      Correct
   2. B
      5.0 × 10⁻⁷ m
   3. C
      1.5 × 10⁻⁷ m
   4. D
      4.0 × 10⁻⁷ m
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   Answer: A

   At the threshold frequency, the photon energy equals the work function: E = hf = hc/λ

   Rearranging: λ = hc/E
   λ = (6.6 × 10⁻³⁴ × 3 × 10⁸) / (8.0 × 10⁻¹⁹)
   λ = (19.8 × 10⁻²⁶) / (8.0 × 10⁻¹⁹)
   λ ≈ 2.475 × 10⁻⁷ m ≈ 2.5 × 10⁻⁷ m

4. 4.A hygrometer is an instrument used to measure
   1. A
      Atmospheric pressure
   2. B
      Temperature
   3. C
      Wind speed
   4. D
      Relative humidity
      Correct
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   Answer: D

   A hygrometer is an instrument used to measure the relative humidity of the atmosphere — the amount of water vapour present in the air relative to the maximum amount the air can hold at that temperature.

   Atmospheric pressure is measured by a barometer, wind speed by an anemometer, and temperature by a thermometer.

5. 5.The image of an object placed at the center of the curvature of a concave mirror is
   1. A
      virtual, erect and magnified
   2. B
      virtual, erect and same size
   3. C
      real, inverted and magnified
   4. D
      real, inverted and same size
      Correct
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   Answer: D

   For a concave mirror, when an object is placed at the centre of curvature C (object distance u = R = 2f):

   Using the mirror formula: 1/v + 1/u = 1/f
   1/v = 1/f − 1/2f = 1/2f ⟹ v = 2f = R

   The image is formed at C also — it is real, inverted, and the same size as the object (magnification = −1).

6. 6.The ice and steam points on a mercury in glass thermometer are found to be 90mm apart. What temperature is recorded in degree Celsius when the length of the mercury thread is 33.6mm above the ice point mark?
   1. A
      37.3°C
      Correct
   2. B
      45.0°C
   3. C
      33.6°C
   4. D
      40.0°C
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   Answer: A

   Using the thermometric formula: θ = (L_θ / L₁₀₀) × 100°C

   where L_θ = 33.6 mm and L₁₀₀ = 90 mm (the ice-to-steam span).

   θ = (33.6 / 90) × 100 = 37.3°C

7. 7.A rectangular coil can rotate in a magnetic field. The two ends of the coil are soldered respectively to the two halves of a commutator. Two carbon brushes are made to press lightly against the commutator and when these are connected in a circuit with a battery and a rheostat, the coil rotates. This is a description of
   1. A
      An AC generator
   2. B
      An AC motor
   3. C
      A DC generator
   4. D
      A DC motor
      Correct
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   Answer: D

   The key features described are: a coil in a magnetic field, a split-ring commutator (two halves), carbon brushes, and connection to a battery (DC source) with a rheostat — causing the coil to rotate.

   This is the description of a DC motor. The commutator reverses the current direction in the coil every half turn, maintaining a continuous torque in one direction.

   An AC generator uses slip rings (not a split commutator) and produces current rather than consuming it.

8. 8.A tap supplies water at 30°C while another supplies at 86°C. If a man wishes to bath with water at 44°C, calculate the ratio of mass of hot water to that of cold water required
   1. A
      3 : 1
   2. B
      1 : 2
   3. C
      2 : 3
   4. D
      1 : 3
      Correct
   Show answerHide answer

   Answer: D

   Using the principle of heat exchange (heat lost by hot water = heat gained by cold water):

   m_h × c × (86 − 44) = m_c × c × (44 − 30)

   m_h × 42 = m_c × 14

   m_h / m_c = 14 / 42 = 1 / 3

   So the ratio of hot water to cold water is 1 : 3.

9. 9.A particle of charge q and mass m moving with a velocity v enters a uniform magnetic field of strength B in the direction of the field. The force on the particle is
   1. A
      zero
      Correct
   2. B
      qB/v
   3. C
      qvB
   4. D
      qvB sin45°
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   Answer: A

   The magnetic force on a charged particle is given by F = qvB sinθ, where θ is the angle between the velocity v and the magnetic field B.

   When the particle moves in the direction of the field, θ = 0°, so sin0° = 0.
   Therefore F = qvB × 0 = zero.

10. 10.A gas occupies a certain volume at 27°C. At what temperature will its volume be three times the original volume assuming that its pressure remains constant?
    1. A
       81°C
    2. B
       900°C
    3. C
       1200°C
    4. D
       627°C
       Correct
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    Answer: D

    At constant pressure, Charles's Law applies: V₁/T₁ = V₂/T₂

    T₁ = 27 + 273 = 300 K, V₂ = 3V₁

    T₂ = 3 × 300 = 900 K

    Converting to Celsius: T₂ = 900 − 273 = 627°C

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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Practise all 38 questions we hold from the 1994 paper, on a timed CBT screen

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