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% Created by Jamb TutorJamb Physics 2020 JAMB PHYSICS PAST QUESTIONS AND ANSWERS 1 / 38 Category: JAMB Physics 2020 1. A few grains of table salt dissolved in cold water over time. Why? a) Convection. b) Osmosis. c) Capillarity. d) Diffusion. Diffusion describes the movement of particles from high to low concentration until equilibrium is reached. 2 / 38 Category: JAMB Physics 2020 2. Force required for an object of mass $m$, velocity $v$ in a circle of radius $r$: a) $\frac{mv^2}{r}$ b) $mr^2x$ c) $mrv$ d) $mvr^2$ Centripetal force is given by $F = \frac{mv^2}{r}$, ensuring circular motion. 3 / 38 Category: JAMB Physics 2020 3. Recoil speed of a machine gun firing a 50 g bullet at 100 m/s (mass gun = 5 kg): a) 0.5 m/s b) 1.5 m/s c) 1 m/s d) 2 m/s Momentum conservation: $m_1v_1 = -m_2v_2$, solving for recoil speed $v_2$ 4 / 38 Category: JAMB Physics 2020 4. Length of pendulum increased by 4x. Period increase by? a) 4 b) $\pi^2$ c) 14 d) 2 $T = 2\pi \sqrt{L/g}$. Increasing L by 4 makes $T$ increase by $\sqrt{4} = 2$ 5 / 38 Category: JAMB Physics 2020 5. Anomalous expansion of water occurs within which temperature range? a) $+208^{\circ}C$ to $+212^{\circ}C$ b) $-80^{\circ}C$ to $-76^{\circ}C$ c) $0^{\circ}C$ to $+4^{\circ}C$ d) $-4^{\circ}C$ to $+0^{\circ}C$ Water expands unusually between 0°C and 4°C due to hydrogen bonding effects. 6 / 38 Category: JAMB Physics 2020 6. Which statements about radioactivity are true? a) i, ii, iii, iv b) i, ii, iii c) iv, v d) i, ii, v Alpha particles are positively charged, beta particles negatively charged, and gamma rays neutral. Statement iv (mass of helium atom) is false. 7 / 38 Category: JAMB Physics 2020 7. Temperature and heat confusion: which statements apply? a) Temperature measures kinetic energy b) Heat is total kinetic energy c) Different heat capacities d) All of the above 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. Key K is closed in the circuit. What happens to current? a) Increases 0.4A b) Decreases 0.4A c) Increases 0.6A d) Decreases 0.6A Closing the key completes the circuit, potentially increasing current by 0.6A if resistance decreases. 9 / 38 Category: JAMB Physics 2020 9. Which use of X-rays is incorrect? a) Photograph tissues b) Treat cancers c) Detect fingerprints d) Reveal flaws in metals X-rays are used medically, in engineering, but not for fingerprint detection (a role for powders). 10 / 38 Category: JAMB Physics 2020 10. Natural radioactivity emits which particles? a) $\alpha, \beta$ b) $\alpha$, X-rays c) $\gamma$, X-rays d) $\alpha, \beta, \gamma$ Alpha particles, beta particles, and gamma rays are products of natural radioactivity. X-rays are manmade. 11 / 38 Category: JAMB Physics 2020 11. A moving solid source produces sound heard differently by a stationary listener. This phenomenon is? a) Doppler Effect b) Resonance c) Ultrasound d) Rarefaction This is the Doppler effect, where sound frequency changes due to relative motion between source and listener. 12 / 38 Category: JAMB Physics 2020 12. What describes high tension transmission? a) High resistance, low voltage b) Low current, high voltage c) High current, low voltage d) High current, low resistance High voltage and low current are used to reduce power loss during electricity transmission. 13 / 38 Category: JAMB Physics 2020 13. Cost of running five 50W lamps and four 100W lamps for 10 hours (energy at 2 Kobo per kWh): a) ₦0.65 b) ₦0.39 c) ₦3.90 d) ₦0.13 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. Mass of a proton is approximately equal to that of which particle? a) α-particle b) β-particle c) Neutron d) Electron Protons and neutrons have comparable masses, whereas electrons and β particles are significantly lighter. 15 / 38 Category: JAMB Physics 2020 15. A transformer with 300 primary turns and 30 secondary turns, input voltage of 100V. Output voltage? a) 5V b) 10V c) 15V d) 20V Transformer ratio: $\frac{V_s}{V_p} = \frac{N_s}{N_p}$. Solve for output voltage: $V_s$ 16 / 38 Category: JAMB Physics 2020 16. 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 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. Measurement of a metal rod using vernier callipers. Likely reading? a) 5.16cm b) 5.165cm c) 5.0cm d) 5.160cm Vernier calipers are accurate to 0.01 cm, so the most likely measurement is 5.16 cm. 18 / 38 Category: JAMB Physics 2020 18. When a sound wave enters water from air, what changes occur? a) Speed/frequency up b) Speed/wavelength up c) Speed down d) Speed up, others down Speed and wavelength increase due to higher density of water, but frequency remains constant. 19 / 38 Category: JAMB Physics 2020 19. Why is a convex mirror used as a driving mirror? a) I, III b) I, II c) II, III d) I, II, III Convex mirrors provide a large field of view and upright images, useful for rear visibility. 20 / 38 Category: JAMB Physics 2020 20. Two mirrors at an angle. Emergent ray deviated by how much? a) $220^{circ}$ b) $200^{circ}$ c) $210^{circ}$ d) $180^{circ}$ Use geometry of ray diagrams to calculate deviation, given angles. Emergent deviation: $220^{\circ}$ 21 / 38 Category: JAMB Physics 2020 21. A magnetic needle at Earth’s magnetic pole and equator. Angles to horizontal? a) 0° and 0° b) 60° and 60° c) 90° and 90° d) 90° and 0° Needle at magnetic pole: 90°, equator: 0°, due to Earth’s magnetic field. 22 / 38 Category: JAMB Physics 2020 22. Hydrometer measures what? a) Depth of water b) Relative density via flotation c) Relative density via weight d) Relative humidity Hydrometers measure the relative density of liquids by flotation principles. 23 / 38 Category: JAMB Physics 2020 23. Three forces acting at a point in equilibrium. Which equation(s) hold? a) I only b) II only c) III only d) I, II, III only Equilibrium implies net force zero. Conditions include: $P_1 \cos \theta_1 = P_2 \cos \theta_2$ and $P_1 \sin \theta_1 = P_2 \sin \theta_2$ 24 / 38 Category: JAMB Physics 2020 24. Refractive index of liquid = 1.5. Velocity of light in vacuum = $3.0 × 10^8$ m/s. Velocity in liquid? a) $1.5 × 10^8$ m/s b) $2.0 × 10^8$ m/s c) $3.0 × 10^8$ m/s d) $4.5 × 10^8$ m/s Refractive index formula: $n = \frac{c}{v}$. Solve for velocity: $v = \frac{c}{n}$ 25 / 38 Category: JAMB Physics 2020 25. Echo received after 3.5s and 2.5s. Speed of sound = 250 m/s. How much closer? a) 10 m b) 350 m c) 175 m d) 125 m Distance = Speed × Time. Difference in distances calculated from time changes gives closeness to the cliff. 26 / 38 Category: JAMB Physics 2020 26. Defects of vision: short-sight and long-sight. Correct statements? a) I only b) II only c) I, II only d) II, III only 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. Total internal reflection: conditions for occurrence? a) I and II only b) II, III only c) III and IV only d) I and III only 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. Linear expansivity of brass = $2 × 10^{-5}$ °C$^{-1}$. Volume at 100°C if initial = 10 cm³? a) 10.06 cm³ b) 10.04 cm³ c) 10.02 cm³ d) 10.20 cm³ Volume expansion $\Delta V = 3 \alpha V_0 \Delta T$. Calculate using given values. 29 / 38 Category: JAMB Physics 2020 29. Mercury thermometer: lower and upper fixed points = 210 mm. Temperature at 49 mm? a) 55.3°C b) 23.3°C c) 49.0°C d) 16.43°C Temperature proportional to height: use formula $\frac{\text{Height – Lower}}{\text{Total Height}} × \text{Temperature Range}$ 30 / 38 Category: JAMB Physics 2020 30. Heat supplied to $10^{-2}$ kg of liquid: 100W for 20 s. Specific heat capacity? a) $2.0 × 10^2$ J/kg/K b) $2.0 × 10^2$ J/kg c) $4.0 × 10^4$ J/kg/K d) $4.0 × 10^4$ J/kg Specific heat: $c = \frac{Q}{m \Delta T}$, where heat $Q = \text{Power} × \text{Time}$. Substitute known values. 31 / 38 Category: JAMB Physics 2020 31. Pressure at depths: Diver G at 20 m and Diver H at 40 m. Ratio of pressures $P_2 / P_1$? a) 0.5 b) 0.6 c) 1.67 d) 2 Pressure proportional to depth. $P_2/P_1 = \text{Depth}_2/\text{Depth}_1$. Calculate ratio. 32 / 38 Category: JAMB Physics 2020 32. Block-and-tackle pulley: Efficiency = 40%, effort W supports load 120 N. What is W? a) 28.0 N b) 48.0 N c) 288.0 N d) 50.0 N Efficiency = Output/Input. Rearrange to calculate effort W. 33 / 38 Category: JAMB Physics 2020 33. Cooling curve: Molten naphthalene cools. 80°C is known as? a) Cooling temperature b) Boiling point c) Melting point d) Vaporization point The temperature plateau in a cooling curve represents the melting/freezing point. 34 / 38 Category: JAMB Physics 2020 34. Circuit diagram: Resistance R is? a) 3Ω b) 6Ω c) 4Ω d) 5Ω Use Ohm’s Law and/or parallel/series resistance formulas based on the circuit. 35 / 38 Category: JAMB Physics 2020 35. Which instrument consumes highest current? Electric iron, TV, torch, immersion heater? a) Electric iron b) Television set c) Torch light d) Immersion heater Current = Power/Voltage. Compare values for each appliance. 36 / 38 Category: JAMB Physics 2020 36. Diagram of wave tube: Which setup shows length equals one wavelength? a) a b) b c) c d) d One wavelength equals distance between two consecutive peaks/troughs. Analyze given diagram. 37 / 38 Category: JAMB Physics 2020 37. Electromagnetic spectrum: Identify correct pair. Radio, sound, gamma, water waves? a) I and II b) III and IV c) I and III d) II and IV Electromagnetic waves include gamma rays and radio waves. Sound/water waves are mechanical waves. 38 / 38 Category: JAMB Physics 2020 38. Substance half-life = 3 min. Count rate after 6 min = 400. What was initial count rate? a) 1600 b) 1200 c) 200 d) 2400 Half-life reduces count rate by half every interval. Calculate initial rate: Rate = $400 × 2^2$ Your score is The average score is 0% LinkedIn Facebook Twitter VKontakte 0% Restart quiz Anonymous feedback Send feedback