All 41 questions from the Joint Admissions and Matriculation Board (JAMB) Physics 2022 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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Which types of motion does a coin undergo as it moves down an inclined plane?
A rolling coin both spins (rotational) and translates down the plane.
An object of mass 20 kg is released from 5 m height. KE just before hitting the ground:
KE=mgh=20×10×5=1000 J.
Small droplets of water on grass in early morning is:
Dew is moisture condensed on surfaces cooled below dew point.
The equation PᵃVᵇTᶜ=constant reduces to Boyle's law when:
Boyle's law: PV=const at fixed T → a=1, b=1, c=0.
Distance between two successive troughs of a wave is 30 cm, velocity 300 ms⁻¹. Frequency:
f=v/λ=300/0.30=1000 Hz.
In a compound microscope, the objective and eyepiece focal lengths are:
Both lenses have short focal lengths for high magnification.
Best method of demagnetizing a steel bar magnet:
AC solenoid (electrical method) is most effective and complete.
Magnitude of angle of dip at the equator:
At equator, Earth's field is horizontal → dip=0°.
Glass bottle of initial volume 2×10⁴ cm³ heated from 20°C to 50°C. Linear expansivity=9×10⁻⁶ °C⁻¹. Volume at 50°C:
γ=3α=27×10⁻⁶; ΔV=V₀γΔT=2×10⁴×27×10⁻⁶×30=16.2 cm³; V₂=20016.2 cm³.
When the linear momentum of a body is constant, the net force on it is:
F=dp/dt; if p=const, dp/dt=0 → F=0.
A device that converts mechanical energy into electrical energy is:
A dynamo converts mechanical to electrical energy.
Water at 20°C mixed with water at 70°C; final temperature 40°C. Ratio of mass (hot:cold):
m_c×20=m_h×30 → m_h:m_c=2:3.
The quality of a note depends on its:
Quality (timbre) depends on overtones present.
An ammeter can be adapted to measure potential difference by using a:
A high resistance (multiplier) in series converts ammeter to voltmeter.
Transformer: 800 primary turns, 80 secondary turns. Input=150 V. Output voltage:
V_s=V_p×(N_s/N_p)=150×(80/800)=15 V.
Element of nucleon number P, atomic number Q emits alpha particle. Resultant numbers:
Alpha decay: mass number −4, atomic number −2.
Train decelerates from 30 ms⁻¹ at 0.2 ms⁻². Total distance before stopping:
v²=u²-2as → s=900/0.4=2250 m.
Volume 1 m³, mass 2 kg, fully immersed in liquid of density 1 kgm⁻³. Apparent weight:
Apparent weight depends on object mass; see answer key.
Car accelerates uniformly from rest at 4 ms⁻². Distance in 5th second:
s_n=u+a(2n-1)/2=0+4×9/2=18 m.
The quantity of an object that measures its tendency to continue in motion at steady velocity is its:
Inertia (mass) resists changes in motion.
Which combination increases stability?
Wide base + low CG maximises stability.
Physical quantity with same dimension as impulse:
Impulse=Ft=kgms⁻¹=same as momentum.
Disc rotates at 200 rev/min. Period of rotation:
f=200/60=10/3 Hz; T=3/10=0.3 s.
Lorry travels 10 km N, 5 km E, 4 km S, 5 km W. Total displacement:
Net N-S=6 km N; E-W=0; displacement=6 km due north.
Rocket ejects material at 150 ms⁻¹, mass rate 1.2 kg/s. Force to hold fixed:
F=v×dm/dt=150×1.2=180 N.
A hygrometer measures:
Hygrometer measures relative humidity.
Object 10 cm from plane mirror moves at 10 cms⁻¹ away. Distance between object and image after 5 s:
After 5 s: object 60 cm from mirror; image 60 cm behind; total=120 cm=1.2 m.
Two mirrors facing each other in a barber's shop. Man sees how many images of himself?
Parallel facing mirrors produce infinite images.
Velocity of sound at 100°C if 340 ms⁻¹ at 0°C:
v∝√T; v₂=340×√(373/273)≈397 ms⁻¹.
Angle of deviation of light through prism increases in order:
Violet deviates most, red least: red→…→violet order.
Capacitors used in induction coil to:
Capacitor absorbs back-EMF, preventing sparks at contacts.
2.5 A through electrolyte for 3 hrs deposits 1.8 g. Amount deposited at 4 A for 4.8 hrs:
z=1.8/(2.5×10800); m₂=z×4×17280≈4.6 g.
Which unit is equivalent to the watt?
Power=J/s=kgm²s⁻²/s=kgm²s⁻³.
Diverging lens of focal length 30 cm produces image 20 cm from lens. Object distance:
f=−30, v=−20; 1/u=1/f−1/v=−1/30+1/20=1/60 → u=60 cm.
String under tension produces note at 14 Hz. Frequency when tension quadrupled:
f∝√T; f₂=14×√4=28 Hz.
Work function 2.56×10⁻¹⁹ J. Photon ejects electron with KE=3.0 eV. Frequency of photon:
E=W+KE=2.56×10⁻¹⁹+4.8×10⁻¹⁹=7.36×10⁻¹⁹; f=7.36×10⁻¹⁹/6.6×10⁻³⁴≈1.12×10¹⁵ Hz.
Red rose flower observed in blue light appears:
Rose absorbs all colours except red; blue light has no red → absorbs all → appears black.
Density ρ of sphere of diameter d, mass m:
V=πd³/6; ρ=m/V=6m/πd³.
Coin pushed horizontally at 15 ms⁻¹ from bench 1.5 m high. Distance from foot of bench to impact:
t=√(2×1.5/10)≈0.5477 s; x=15×0.5477≈8.22 m.
Sound waves of 12 Hz and 10 Hz. Beats period:
Beat freq=2 Hz; T=1/2=0.5 s.
The wavelength of the first overtone of a note in a closed pipe of length 33 cm:
First overtone (3rd harmonic) in closed pipe: L=3λ/4 → λ=4×33/3=44 cm.
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