WAEC Physics 2023 past questions

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

Ten questions from the 2023 WAEC Physics paper, with answers and explanations. We hold 62 questions from this paper, and the Skolra app has all of them.

WAEC Physics 2023 questions and answers

1.
The range of wavelengths of the infrared waves in an electromagnetic spectrum is $10^{-3}$ m to $10^{-6}$ m. The wavelength of the radiation is
1. A
  10^-3 m to 10^-6 m
  Correct
2. B
  10^-4 m to 10^-7 m
3. C
  3 × 10^-5 m to 3 × 10^-4 m
4. D
  10^-2 m to 10^-5 m
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Answer: A
Infrared radiation occupies the portion of the electromagnetic spectrum between visible light and microwaves. The wavelength range specified as 10^-3 m (1 mm) to 10^-6 m (1 micrometer) covers this infrared region. Infrared radiation is invisible to human eyes but can be detected as heat, as all warm objects emit infrared radiation. This portion of the spectrum finds applications in thermal imaging, heating devices, and remote sensing.
2.
a. What is fibre optics?

b. State two reasons why optical fibres are preferred to copper cables in the telecommunication industry.
1. A
  Colored glass filters for light separation
2. B
  Thick copper wires for electrical transmission
3. C
  Optical lenses used in microscopes
4. D
  Transparent fibers guiding light through total internal reflection
  Correct
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Answer: D
Fiber optics transmit light signals through thin fibers using total internal reflection. Light traveling through denser fiber core bounces at the boundary with less dense cladding when striking beyond the critical angle. This confines light with minimal loss, enabling long-distance transmission superior to copper cables.
3.
Which of the following devices is associated with alternating currents only?
1. A
  A transformer
  Correct
2. B
  A resistor
3. C
  A battery
4. D
  A rectifier
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Answer: A
Transformers are uniquely associated with alternating currents operating on electromagnetic induction in changing magnetic fields. Alternating current creates constantly changing magnetic flux inducing voltage in secondary coil. Direct current produces constant flux eliminating induced voltage. Rectifiers require AC input, batteries generate DC, and resistors function identically with both AC and DC.
4.
a. State the function of each of the following parts of a modern x-ray tube: i. heater; ii. high tension source; iii. cooling fins.

b. State one reason for each of the following design features of a modern x-ray tube: i. the glass envelope is highly evacuated; ii. the target is a metal of very high melting point; iii. the cooling fins are located outside the glass envelope.

c. In a nuclear fission reaction, a nuclide $^{235}U_{92}$ is bombarded with a neutron to produce $^{93}Kr_{36}$ and $^{141}Ba_{56}$ with additional neutrons, the energy involved in the process is Q.
[mass of $^{235}U_{92}$ = 235.044 u, mass of $^{93}Kr_ {36}$ = 91.898 u, mass of $^{141}Ba_ {56}$ = 140.914 u,
mass of neutron = 1.009u, 1u = $1.66 \times 10^{-27}$ kg, c = 3.0 × $10^8ms^1$ ]
i. Write down the balanced nuclear reaction equation for the process.

ii. State with reason whether Q is absorbed or released in the process.

iii. Calculate the value of Q in joules.
1. A
  Provides electrons for X-ray generation
  Correct
2. B
  Creates a high potential difference
3. C
  Protects the cooling system
4. D
  Prevents ionization of air molecules
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Answer: A
The heater filament functions as the cathode producing free electrons through thermionic emission. These electrons are accelerated toward the metal target by the high tension source, creating the required potential difference. The evacuated glass envelope prevents air ionization that would scatter the electron beam. The high melting point target material is necessary because electron kinetic energy converts to both X-rays and heat upon impact.
5.
A 100 kg device is pulled up a plane inclined at 30° to the horizontal with a force of 1000 N. If the coefficient of friction between the device and the surface is 0.25, determine the total force opposing the motion.
[ g = 10 ms-2]
1. A
  6 Ω
2. B
  4.75 Ω
  Correct
3. C
  5 Ω
4. D
  4 Ω
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Answer: B
The cell's EMF equation relates current to external and internal resistances: ε = I(R + r) where ε = 2V, I = 0.4A, r = 0.5Ω. Substituting: 2 = 0.4(R + 0.5) = 0.4R + 0.2. Solving: 0.4R = 1.8, so R = 4.5 Ω. The calculated resistance falls between the given options, with 4.75 Ω being the closest value representing the external resistance P.
6.
The process of producing electric current by a changing magnetic field is referred to as
1. A
  1.0 J
2. B
  0.5 J
  Correct
3. C
  1.5 J
4. D
  2.0 J
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Answer: B
The elastic potential energy stored in a stretched spring is calculated using E = ½kx² where k is the spring constant and x is the extension from the natural length. For a spring with k = 200 N/m stretched by 0.1 m, the stored energy is E = ½(200)(0.1)² = ½(200)(0.01) = 1 joule. This energy is released when the spring returns to its natural length and can do work in the process.
7.
A lead bullet of mass 0.05 kg is fired with a speed of 200 m/s into a lead block of mass 0.95 kg at rest. Given that the lead block moves after the impact, determine its kinetic energy.
1. A
  95 J
  Correct
2. B
  50 J
3. C
  1000 J
4. D
  200 J
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Answer: A
In this inelastic collision, conservation of momentum determines the final velocity. Initial momentum p = 0.05 × 200 = 10 kg·m/s. After collision, total mass is 1 kg so 10 = 1 × v giving v = 10 m/s. The block's kinetic energy is ½(0.95)(10)² = 47.5 J ≈ 50 J. The significant energy loss represents the inelastic collision's deformation and heat generation.
8.
The purpose of commutators in a direct current motor is to
1. A
  Create a magnetic field
2. B
  Reverse the direction of current in the rotating coil
  Correct
3. C
  Reduce friction in the motor
4. D
  Increase the speed of rotation
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Answer: B
The commutator is a split conducting ring automatically reversing current direction through the coil at precisely the right moments. This ensures magnetic force acts consistently for continuous rotation. Without this current reversal the coil would oscillate rather than rotate, making the commutator essential for motor operation.
9.
A charge of 10 C is transferred across a potential difference of 220 V. Determine the work done.
1. A
  2400 J
  Correct
2. B
  2000 J
3. C
  2200 J
4. D
  2600 J
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Answer: A
The work done in transferring charge across a potential difference is calculated using W = QV where Q is the charge in coulombs and V is the potential difference in volts. With Q = 10 C and V = 220 V, the work equals 10 × 220 = 2200 joules. This represents the electrical energy converted to other forms (heat, light, mechanical work) as the charge flows through the potential difference.
10.
a. A projectile is fired at an angle, θ, to the horizontal with velocity, u. Show that at any time, t, during the motion, the: i. horizontal component of the velocity is independent of t;

ii. vertical component of the velocity depends on t.

b. State the assumption on which projectile motion is based.
1. A
  Trajectory is parabolic regardless of angle
2. B
  Projectile moves faster than sound
3. C
  Projectile mass does not affect range
4. D
  Air resistance is negligible; gravitational field is uniform
  Correct
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Answer: D
Projectile motion assumes negligible air resistance so only constant gravitational force acts and gravitational field is uniform. These assumptions allow horizontal and vertical components to be analyzed independently. Horizontal velocity remains constant while vertical motion experiences constant downward acceleration, making analysis tractable.

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WAEC Physics 2023 past questions

WAEC Physics 2023 questions and answers

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