2020 JAMB PHYSICS PAST QUESTIONS AND ANSWERS Leave a Comment / Jamb Physics / By Jamb Tutor Report a question What’s wrong with this question? You cannot submit an empty report. Please add some details. 0% 0 votes, 0 avg Created by Jamb TutorJamb Physics 2020 JAMB PHYSICS PAST QUESTIONS AND ANSWERS 1 / 38 Category: JAMB Physics 2020 1. $$\text{A few grains of table salt dissolved in cold water over time. Why?}$$ a) $$\text{Convection.}$$ b) $$\text{Osmosis.}$$ c) $$\text{Capillarity.}$$ d) $$\text{Diffusion.}$$ $$\text{Diffusion describes the movement of particles from high to low concentration until equilibrium is reached.}$$ 2 / 38 Category: JAMB Physics 2020 2. $$\text{Force required for an object of mass } m, \text{ velocity } v \text{ in a circle of radius } r:$$ a) $$\frac{mv^2}{r}.$$ b) $$mr^2x.$$ c) $$mrv.$$ d) $$mvr^2.$$ $$\text{Centripetal force is given by } F = \frac{mv^2}{r}, \text{ ensuring circular motion.}$$ 3 / 38 Category: JAMB Physics 2020 3. $$\text{Recoil speed of a machine gun firing a 50 g bullet at 100 m/s (mass gun = 5 kg):}$$ a) $$0.5 \text{ m/s.}$$ b) $$1.5 \text{ m/s.}$$ c) $$1 \text{ m/s.}$$ d) $$2 \text{ m/s.}$$ $$\text{Momentum conservation: } m_1v_1 = -m_2v_2, \text{ solving for recoil speed } v_2.\text{}$$ 4 / 38 Category: JAMB Physics 2020 4. $$\text{Length of pendulum increased by 4x. Period increase by?}$$ a) $$4.$$ b) $$\pi^2.$$ c) $$14.$$ d) $$2.$$ $$\text{T = 2\pi \sqrt{L/g}. \text{ Increasing L by 4 makes } T \text{ increase by } \sqrt{4} = 2.}$$ 5 / 38 Category: JAMB Physics 2020 5. $$\text{Anomalous expansion of water occurs within which temperature range?}$$ a) $$+208^{\circ}C \text{ to } +212^{\circ}C.$$ b) $$-80^{\circ}C \text{ to } -76^{\circ}C.$$ c) $$0^{\circ}C \text{ to } +4^{\circ}C.$$ d) $$-4^{\circ}C \text{ to } +0^{\circ}C.$$ $$\text{Water expands unusually between 0°C and 4°C due to hydrogen bonding effects.}$$ 6 / 38 Category: JAMB Physics 2020 6. $$\text{Which statements about radioactivity are true?}$$ a) $$i, ii, iii, iv.$$ b) $$i, ii, iii.$$ c) $$iv, v.$$ d) $$i, ii, v.$$ $$\text{Alpha particles are positively charged, beta particles negatively charged, and gamma rays neutral. } \text{Statement iv (mass of helium atom) is false.}$$ 7 / 38 Category: JAMB Physics 2020 7. $$\text{Temperature and heat confusion: which statements apply?}$$ a) $$\text{Temperature measures kinetic energy.}$$ b) $$\text{Heat is total kinetic energy.}$$ c) $$\text{Different heat capacities.}$$ d) $$\text{All of the above.}$$ $$\text{Temperature measures average kinetic energy; heat measures total kinetic energy. Different materials require different heat for temperature changes.}$$ 8 / 38 Category: JAMB Physics 2020 8. $$\text{Key K is closed in the circuit. What happens to current?}$$ a) $$\text{Increases 0.4A.}$$ b) $$\text{Decreases 0.4A.}$$ c) $$\text{Increases 0.6A.}$$ d) $$\text{Decreases 0.6A.}$$ $$\text{Closing the key completes the circuit, potentially increasing current by 0.6A if resistance decreases.}$$ 9 / 38 Category: JAMB Physics 2020 9. $$\text{Which use of X-rays is incorrect?}$$ a) $$\text{Treat cancers.}$$ b) $$\text{Detect fingerprints.}$$ c) $$\text{Reveal flaws in metals.}$$ d) $$\text{Photograph tissues.}$$ $$\text{X-rays are used medically, in engineering, but not for fingerprint detection (a role for powders).}$$ 10 / 38 Category: JAMB Physics 2020 10. $$\text{Natural radioactivity emits which particles?}$$ a) $$\text{\alpha, \beta.}$$ b) $$\text{\alpha, X-rays.}$$ c) $$\text{\gamma, X-rays.}$$ d) $$\text{\alpha, \beta, \gamma.}$$ $$\text{Alpha particles, beta particles, and gamma rays are products of natural radioactivity. X-rays are manmade.}$$ 11 / 38 Category: JAMB Physics 2020 11. $$\text{A moving solid source produces sound heard differently by a stationary listener. This phenomenon is?}$$ a) $$\text{Doppler Effect.}$$ b) $$\text{Resonance.}$$ c) $$\text{Ultrasound.}$$ d) $$\text{Rarefaction.}$$ $$\text{This is the Doppler effect, where sound frequency changes due to relative motion between source and listener.}$$ 12 / 38 Category: JAMB Physics 2020 12. $$\text{What describes high tension transmission?}$$ a) $$\text{High resistance, low voltage.}$$ b) $$\text{Low current, high voltage.}$$ c) $$\text{High current, low voltage.}$$ d) $$\text{High current, low resistance.}$$ $$\text{High voltage and low current are used to reduce power loss during electricity transmission.}$$ 13 / 38 Category: JAMB Physics 2020 13. $$\text{Cost of running five 50W lamps and four 100W lamps for 10 hours (energy at 2 Kobo per kWh):}$$ a) $$\text{₦0.65.}$$ b) $$\text{₦0.39.}$$ c) $$\text{₦3.90.}$$ d) $$\text{₦0.13.}$$ $$\text{Power = (5 × 50 + 4 × 100) W, Total energy = Power × time in kWh. Multiply by unit cost to find total.}$$ 14 / 38 Category: JAMB Physics 2020 14. $$\text{Mass of a proton is approximately equal to that of which particle?}$$ a) $$\text{\alpha-particle.}$$ b) $$\text{\beta-particle.}$$ c) $$\text{Neutron.}$$ d) $$\text{Electron.}$$ $$\text{Protons and neutrons have comparable masses, whereas electrons and \beta particles are significantly lighter.}$$ 15 / 38 Category: JAMB Physics 2020 15. $$\text{A transformer with 300 primary turns and 30 secondary turns, input voltage of 100V. Output voltage?}$$ a) $$5V.$$ b) $$10V.$$ c) $$15V.$$ d) $$20V.$$ $$\text{Transformer ratio: } \frac{V_s}{V_p} = \frac{N_s}{N_p}. \text{ Solve for output voltage: } V_s.}$$ 16 / 38 Category: JAMB Physics 2020 16. $$\text{A solid weighs 4.8g in air, 2.8g in water, and 3.2g in kerosene. Density ratio solid:kerosene?}$$ a) $$2.$$ b) $$32.$$ c) $$23.$$ d) $$3.$$ $$\text{Using density ratios: } \rho_{\text{solid}} / \rho_{\text{kerosene}} = W_{\text{solid-air}} / (W_{\text{solid-air}} – W_{\text{solid-kerosene}}).$$ 17 / 38 Category: JAMB Physics 2020 17. $$\text{Measurement of a metal rod using vernier callipers. Likely reading?}$$ a) $$5.16cm.$$ b) $$5.165cm.$$ c) $$5.0cm.$$ d) $$5.160cm.$$ $$\text{Vernier calipers are accurate to 0.01 cm, so the most likely measurement is 5.16 cm.}$$ 18 / 38 Category: JAMB Physics 2020 18. $$\text{When a sound wave enters water from air, what changes occur?}$$ a) $$\text{Speed/frequency up.}$$ b) $$\text{Speed/wavelength up.}$$ c) $$\text{Speed down.}$$ d) $$\text{Speed up, others down.}$$ $$\text{Speed and wavelength increase due to higher density of water, but frequency remains constant.}$$ 19 / 38 Category: JAMB Physics 2020 19. $$\text{Why is a convex mirror used as a driving mirror?}$$ a) $$\text{I, III.}$$ b) $$\text{I, II.}$$ c) $$\text{II, III.}$$ d) $$\text{I, II, III.}$$ $$\text{Convex mirrors provide a large field of view and upright images, useful for rear visibility.}$$ 20 / 38 Category: JAMB Physics 2020 20. $$\text{Two mirrors at an angle. Emergent ray deviated by how much?}$$ a) $$220^{\circ}. $$ b) $$200^{\circ}. $$ c) $$210^{\circ}. $$ d) $$180^{\circ}. $$ $$\text{Use geometry of ray diagrams to calculate deviation, given angles. Emergent deviation: } 220^{\circ}.$$ 21 / 38 Category: JAMB Physics 2020 21. $$\text{A magnetic needle at Earth’s magnetic pole and equator. Angles to horizontal?}$$ a) $$\text{0° and 0°.}$$ b) $$\text{60° and 60°.}$$ c) $$\text{90° and 90°.}$$ d) $$\text{90° and 0°.}$$ $$\text{Needle at magnetic pole: 90°, equator: 0°, due to Earth’s magnetic field.}$$ 22 / 38 Category: JAMB Physics 2020 22. $$\text{Hydrometer measures what?}$$ a) $$\text{Depth of water.}$$ b) $$\text{Relative density via flotation.}$$ c) $$\text{Relative density via weight.}$$ d) $$\text{Relative humidity.}$$ $$\text{Hydrometers measure the relative density of liquids by flotation principles.}$$ 23 / 38 Category: JAMB Physics 2020 23. $$\text{Three forces acting at a point in equilibrium. Which equation(s) hold?}$$ a) $$\text{I only.}$$ b) $$\text{II only.}$$ c) $$\text{III only.}$$ d) $$\text{I, II, III only.}$$ $$\text{Equilibrium implies net force zero. Conditions include: } P_1 \cos \theta_1 = P_2 \cos \theta_2 \text{ and } P_1 \sin \theta_1 = P_2 \sin \theta_2.$$ 24 / 38 Category: JAMB Physics 2020 24. $$\text{Refractive index of liquid = 1.5. Velocity of light in vacuum = 3.0 × 10^8 m/s. Velocity in liquid?}$$ a) $$\text{1.5 × 10^8 m/s.}$$ b) $$\text{2.0 × 10^8 m/s.}$$ c) $$\text{3.0 × 10^8 m/s.}$$ d) $$\text{4.5 × 10^8 m/s.}$$ $$\text{Refractive index formula: } n = \frac{c}{v}. \text{ Solve for velocity: } v = \frac{c}{n}. $$ 25 / 38 Category: JAMB Physics 2020 25. $$\text{Echo received after 3.5s and 2.5s. Speed of sound = 250 m/s. How much closer?}$$ a) $$\text{10 m.}$$ b) $$\text{350 m.}$$ c) $$\text{175 m.}$$ d) $$\text{125 m.}$$ $$\text{Distance = Speed × Time. Difference in distances calculated from time changes gives closeness to the cliff.}$$ 26 / 38 Category: JAMB Physics 2020 26. $$\text{Defects of vision: short-sight and long-sight. Correct statements?}$$ a) $$\text{I only.}$$ b) $$\text{II only.}$$ c) $$\text{I, II only.}$$ d) $$\text{II, III only.}$$ $$\text{Short-sight means distant objects blur; corrected by concave lenses. Long-sight means close objects blur. Correct combinations apply.}$$ 27 / 38 Category: JAMB Physics 2020 27. $$\text{Total internal reflection: conditions for occurrence?}$$ a) $$\text{I and II only.}$$ b) $$\text{II, III only.}$$ c) $$\text{III and IV only.}$$ d) $$\text{I and III only.}$$ $$\text{Light passes from denser to less dense medium at angle greater than critical angle for total internal reflection.}$$ 28 / 38 Category: JAMB Physics 2020 28. $$\text{Linear expansivity of brass = 2 × 10^{-5} °C^{-1}. Volume at 100°C if initial = 10 cm³?}$$ a) $$\text{10.06 cm³.}$$ b) $$\text{10.04 cm³.}$$ c) $$\text{10.02 cm³.}$$ d) $$\text{10.20 cm³.}$$ $$\text{Volume expansion } \Delta V = 3 \alpha V_0 \Delta T. \text{ Calculate using given values.}$$ 29 / 38 Category: JAMB Physics 2020 29. $$\text{Mercury thermometer: lower and upper fixed points = 210 mm. Temperature at 49 mm?}$$ a) $$\text{55.3°C.}$$ b) $$\text{23.3°C.}$$ c) $$\text{49.0°C.}$$ d) $$\text{16.43°C.}$$ $$\text{Temperature proportional to height: use formula } \frac{\text{Height – Lower}}{\text{Total Height}} \times \text{Temperature Range}. $$ 30 / 38 Category: JAMB Physics 2020 30. $$\text{Heat supplied to 10^{-2} kg of liquid: 100W for 20 s. Specific heat capacity?}$$ a) $$\text{2.0 × 10² J/kg/K.}$$ b) $$\text{2.0 × 10² J/kg.}$$ c) $$\text{4.0 × 10⁴ J/kg/K.}$$ d) $$\text{4.0 × 10⁴ J/kg.}$$ $$\text{Specific heat: } c = \frac{Q}{m \Delta T}, \text{ where heat } Q = Power \times Time. Substitute known values.}$$ 31 / 38 Category: JAMB Physics 2020 31. $$\text{Pressure at depths: Diver G at 20 m and Diver H at 40 m. Ratio of pressures P_2 / P_1?}$$ a) $$\text{0.50.}$$ b) $$\text{0.60.}$$ c) $$\text{1.67.}$$ d) $$\text{2.00.}$$ $$\text{Pressure proportional to depth. P_2/P_1 = Depth_2/Depth_1. Calculate ratio.}$$ 32 / 38 Category: JAMB Physics 2020 32. $$\text{Block-and-tackle pulley: Efficiency = 40%, effort W supports load 120 N. What is W?}$$ a) $$\text{28.0 N.}$$ b) $$\text{48.0 N.}$$ c) $$\text{288.0 N.}$$ d) $$\text{50.0 N.}$$ $$\text{Efficiency = Output/Input. Rearrange to calculate effort W.}$$ 33 / 38 Category: JAMB Physics 2020 33. $$\text{Cooling curve: Molten naphthalene cools. 80°C is known as?}$$ a) $$\text{Cooling temperature.}$$ b) $$\text{Boiling point.}$$ c) $$\text{Melting point.}$$ d) $$\text{Vaporization point.}$$ $$\text{The temperature plateau in a cooling curve represents the melting/freezing point.}$$ 34 / 38 Category: JAMB Physics 2020 34. $$\text{Circuit diagram: Resistance R is?}$$ a) $$\text{3Ω.}$$ b) $$\text{6Ω.}$$ c) $$\text{4Ω.}$$ d) $$\text{5Ω.}$$ $$\text{Use Ohm’s Law and/or parallel/series resistance formulas based on the circuit.}$$ 35 / 38 Category: JAMB Physics 2020 35. $$\text{Which instrument consumes highest current? Electric iron, TV, torch, immersion heater?}$$ a) $$\text{Electric iron.}$$ b) $$\text{Television set.}$$ c) $$\text{Torch light.}$$ d) $$\text{Immersion heater.}$$ $$\text{Current = Power/Voltage. Compare values for each appliance.}$$ 36 / 38 Category: JAMB Physics 2020 36. $$\text{Diagram of wave tube: Which setup shows length equals one wavelength?}$$ a) $$\text{a.}$$ b) $$\text{b.}$$ c) $$\text{c.}$$ d) $$\text{d.}$$ $$\text{One wavelength equals distance between two consecutive peaks/troughs. Analyze given diagram.}$$ 37 / 38 Category: JAMB Physics 2020 37. $$\text{Electromagnetic spectrum: Identify correct pair. Radio, sound, gamma, water waves?}$$ a) $$\text{I and II.}$$ b) $$\text{III and IV.}$$ c) $$\text{I and III.}$$ d) $$\text{II and IV.}$$ $$\text{Electromagnetic waves include gamma rays and radio waves. Sound/water waves are mechanical waves.}$$ 38 / 38 Category: JAMB Physics 2020 38. $$\text{Substance half-life = 3 min. Count rate after 6 min = 400. What was initial count rate?}$$ a) $$\text{1600.}$$ b) $$\text{1200.}$$ c) $$\text{200.}$$ d) $$\text{2400.}$$ $$\text{Half-life reduces count rate by half every interval. Calculate initial rate: } \text{Rate = } 400 \times 2^2. $$ Your score is The average score is 0% LinkedIn Facebook Twitter VKontakte 0% Restart quiz Anonymous feedback Send feedback
