JAMB Physics 2025 past questions

Checked by the Skolra question team · Last updated 23 October 2026

Ten questions from the 2025 JAMB Physics paper, with answers and explanations. We hold 59 questions from this paper, and the Skolra app has all of them.

JAMB Physics 2025 questions and answers

1.
Without considering the containing vessel, what mass of boiled water can raise the temperature of 8 kg of water from 25°C to 60°C when mixed in a heat-proof container?
1. A
  6 kg
2. B
  8 kg
3. C
  9.1 kg
4. D
  7 kg
  Correct
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Answer: D
This is a heat-exchange (calorimetry) problem. "Boiled water" means water at its boiling point, 100°C.
Heat lost by the boiled water (cooling from 100°C to the final temperature 60°C) equals heat gained by the 8 kg of water (heating from 25°C to 60°C), since the container is heat-proof and no heat escapes.
Using mcΔθ (heat lost) = mcΔθ (heat gained):
m × (100 − 60) = 8 × (60 − 25)
m × 40 = 8 × 35
m × 40 = 280
m = 280 ÷ 40 = 7 kg
So 7 kg of boiled water is needed.
2.
A well-lagged thin metal rod of length 0.2 m has a temperature gradient of 416 K m $^{-1}$ . If one end is at 233º C, what is the temperature at the other end?
1. A
  149.8°C
  Correct
2. B
  150.8°C
3. C
  316.2°C
4. D
  83.2°C
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Answer: A
Working: Temperature gradient tells you how much the temperature changes per metre along the rod: 416 K m⁻¹. Over a length of 0.2 m, the total temperature drop is:
ΔT = gradient × length = 416 × 0.2 = 83.2 K (= 83.2 °C, since a change of 1 K equals a change of 1 °C).
Since the rod is well-lagged, heat flows steadily from the hotter end to the cooler end, so temperature falls along the rod. Starting from 233°C and subtracting the drop:
Other end = 233 − 83.2 = 149.8°C.
3.
What form of energy is present in the food we eat?
1. A
  Heat energy
2. B
  Chemical energy
  Correct
3. C
  Kinetic energy
4. D
  Mechanical energy
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Answer: B
Food stores energy in the chemical bonds holding its molecules (carbohydrates, fats and proteins) together. This stored form is chemical energy, a type of potential energy.
When the body digests and respires this food, the chemical energy is converted into other useful forms — such as heat energy to keep the body warm, and kinetic (mechanical) energy for movement and muscle work. But those forms are the output of the conversion, not what is present in the food itself.
Choosing heat energy or kinetic/mechanical energy confuses the energy the body produces after respiration with the energy actually stored in the food before it is eaten.
4.
A 500W electric oven plugged into a 220 V source will consume an electric current of
1. A
  2.3 A
  Correct
2. B
  0.44 A
3. C
  1.1 A
4. D
  22.3 A
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Answer: A
The power rating of an electrical appliance is related to voltage and current by P = VI.
Making current the subject: I = P / V.
Substituting the values given: I = 500 W ÷ 220 V = 2.27 A, which rounds to 2.3 A. This is the correct current drawn by the oven.
5.
The gravitational force between two masses, P and Q, is 10N, find the new value of the force if both masses are doubled
1. A
  40 N
  Correct
2. B
  20 N
3. C
  5 N
4. D
  80 N
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Answer: A
By Newton's law of universal gravitation, F = Gm₁m₂/r², the force depends on the product of the two masses.
Doubling one mass alone would double the force, but here both masses P and Q are doubled. Since force is proportional to m₁ × m₂, doubling both masses multiplies the force by 2 × 2 = 4.
New force = 4 × 10 N = 40 N.
The option giving 20 N comes from doubling only one mass and forgetting the second. The option giving 5 N wrongly treats the relationship as inverse, as though the masses were in the denominator like distance. The option giving 80 N comes from mistakenly cubing the scale factor (2³ = 8) instead of using it correctly as 2 × 2 = 4.
6.
Standing waves are produced by
1. A
  a single progressive wave reflecting through a change in medium density
2. B
  the diffraction of a wave as it passes through a narrow slit
3. C
  the superposition of two progressive waves of the same frequency and amplitude travelling in opposite directions
  Correct
4. D
  the superposition of two progressive waves of different frequencies travelling in the same direction
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Answer: C
Standing (stationary) waves are produced when two progressive waves of the same frequency and amplitude, travelling in opposite directions, meet and superpose — for example, a wave sent along a string and its reflection travelling back. Where the waves are in phase they reinforce (antinodes); where they are out of phase they cancel (nodes). This is how standing waves form on a stretched string or in an air column.
7.
Calculate the decay constant of a radioactive isotope of half-life 138.5 s.
1. A
  7.2 × 10⁻³ s⁻¹
2. B
  1.4 × 10⁻² s⁻¹
3. C
  5.0 × 10⁻³ s⁻¹
  Correct
4. D
  2.5 × 10⁻³ s⁻¹
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Answer: C
The decay constant λ is related to the half-life t½ of a radioactive isotope by the formula:
λ = ln(2) / t½
Substituting the given half-life, t½ = 138.5 s:
λ = 0.693 / 138.5 = 0.005 s⁻¹
So 5.0 × 10⁻³ s⁻¹ is correct.
A candidate who mistakenly uses 1/t½ instead of ln(2)/t½ (forgetting the ln(2) factor entirely) gets 7.2 × 10⁻³ s⁻¹, which is wrong because it ignores the logarithmic relationship between decay constant and half-life.
Using 2/t½ instead of ln(2)/t½ (confusing the "2" in half-life with the natural log of 2) gives 1.4 × 10⁻² s⁻¹, also wrong.
8.
A refrigerator uses 150W. If it is kept on for 336 hours nonstop. What is the energy consumed in Kwh?
1. A
  5.04 kWh
2. B
  5040 kWh
3. C
  50.4 kWh
  Correct
4. D
  504 kWh
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Answer: C
Energy consumed (in kWh) = Power (in kW) × Time (in hours).
First convert the power to kilowatts: 150 W = 150/1000 = 0.15 kW.
Then multiply by the time the refrigerator ran: 0.15 kW × 336 h = 50.4 kWh.
A candidate who forgets to convert watts to kilowatts and just multiplies 150 × 336 gets 50,400, and if they then misplace the decimal point while trying to fix the units they can land on 5040 kWh or 504 kWh instead of correctly dividing by 1000 to get 50.4 kWh. Always convert to kilowatts first, then multiply by the hours.
9.
The volume of a 1 cm $^3$ metal ball increases by 0.0018 cm $^3$ when heated through temperature θ. If the linear expansivity of the ball is 2.0 x 10 $^{-5} K^{-1}$ , find θ.
1. A
  45 K
2. B
  90 K
3. C
  30 K
  Correct
4. D
  15 K
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Answer: C
For a solid that expands in all three dimensions, the cubic (volumetric) expansivity is three times the linear expansivity: γ = 3α.
Using ΔV = γVθ = 3αVθ, and given ΔV = 0.0018 cm³, V = 1 cm³, α = 2.0 × 10⁻⁵ K⁻¹:
θ = ΔV ÷ (3αV) = 0.0018 ÷ (3 × 2.0 × 10⁻⁵ × 1) = 0.0018 ÷ 0.00006 = 30 K.
A candidate who forgets the factor of 3 and uses ΔV = αVθ directly lands on 90 K — that mistake ignores that volume expansion happens along all three axes, not just one. Using 2α instead of 3α (mixing up area expansivity, which is 2α, with volume expansivity) gives 45 K. Using 6α (doubling the correct factor by mistake) gives 15 K. The correct physics is that volumetric expansivity is three times linear expansivity, giving 30 K.
10.
A 25cm long pinhole camera produces a one-fifth of an object's size. Calculate the object distance
1. A
  5cm
2. B
  500cm
3. C
  250cm
4. D
  125cm
  Correct
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Answer: D
In a pinhole camera, the image forms on the screen at the back of the box, so the image distance equals the length of the camera, which is 25 cm.
The magnification relates image size to object size in the same way it relates image distance to object distance:
m = image size / object size = image distance / object distance
Since the image size is one-fifth of the object size, m = 1/5. Substituting the image distance:
1/5 = 25 / object distance
object distance = 25 × 5 = 125 cm

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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JAMB Physics 2025 past questions

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