Physics 2017 JAMB Past Questions
Physics 2017 JAMB Past Questions
1. Which is the incorrect formula for a body accelerating uniformly?
- A. a = v2 −
Correct Answer: Option A
Explanation
Look through the equations of motion
2.Which of the following is not an electromagnetic radiation?
- A. x - ray
- B. Radio waves
- C. sunlight
- D. sound waves
Explanation
Electromagnetic waves do not require any material medium, but sound waves is a mechanical wave that require a material medium
3. Calculate the electric field intensity between two plates of potential difference 6.5V when separated by a distance of 35cm.
- A. 18.57NC
Correct Answer: Option A
=
=
=
= 18.57NC
Explanation
Electric Field Intensity (E) ==
=
=
= 18.57NC
4. Why do soldiers march disorderly while crossing a bridge?
- A. To prevent resonance on the bridge
- B. To set the bridge into resonance
- C. To make the b ridge collapse
- D. To spread their weight evenly on the bridge
Correct Answer: Option A
Explanation
Soldiers march disorderly while crossing a bridge to prevent resonance because when soldiers march in orderly manner across a bridge, they generate a rhythmic oscillation of wave on the bridge and at a certain point, would start oscillation to the same rhym as that of the marching steps. This oscillation would reach a maximum peak when the bridge can no longer sustain its own strength and hence collapses. So for this reasons, soldier are ordered to march disorderly while crossing a bridge
5. Calculate the upthrust on an object of volume 50cm3 which is immersed in liquid of density 103kgm-3 [g = 10ms-2]
- A. 0.8N
- B. 2.5N
- C. 0.5N
- D. 1.0N
Explanation
Upthrust = change in weightdensity =
Mass of liquid displaced = Density of Liquid × Volume;
=
= 0.05kg
(Note that the volume of was converted to by multiplying by ) i.e
Since mass displaced = 0.05kg
Upthrust = mg = 0.05 × 10
= 0.5N
6.Under what conditions are cathode rays produced in a discharge tube?
- A. High pressure and low voltage
- B. High pressure and high voltage
- C. Low pressure and low voltage
- D. Low pressure and high volatge
Explanation
Cathode rays are produced in a discharge tube under Low pressure and high voltage
7.Under which of the following conditions is workdone
- A. A man supports a heavy food above his head with his hands
- B. A boy climbs onto a table
- C. A man pushes unto a table
- D. A woman holds a pot of water
Explanation
For work to be done, distance must be involved becauseworkdone = force × distance
8.Calculate
the specific latent heat of vaporization of steam of 1.13 x 106J of heat
energy is required to convert 15kg of steam to water.
- A. 7.53 x 105 Jkg
Correct Answer: Option C
Q = mL
L =
=
= Jkg
Explanation
Quantity of heat = mass(m) × specific latent heat (L)Q = mL
L =
=
= Jkg
9.A cell of internal resistance 2 π supplies current to a 6 π resistor. The efficiency of the cell is
- A. 12.0%
- B. 25.0%
- C. 33.3%
- D. 75.0%
Explanation
Internal resistance determine the maximum current that can be suppliedEfficiency =
× 100
= × 100
= 33.3%
10.Which of the following statements is NOT correct?
Brownian motion is an evidence of particle nature of matter
matter is made up of molecules
The molecules of matter are in constant motion
- A. Molecules of a liquid are stationary
- B. Brownian motion is an evidence of particle nature of matter
- C. Matter is made up of molecules
- D. The molecules of matter are in constant motion
Explanation
Molecules of liquid are not stationaryBrownian motion is an evidence of particle nature of matter
matter is made up of molecules
The molecules of matter are in constant motion
11.A block and
tackle pulley arrangement has 6 pulleys in which an effort of 50N
supports a load of 200N, calculate the efficiency of the machine
V.R = number of pulleys = 6
ma = = = 4
Effiecieny = × 100 = 66.67%
= + +
= = = 1
Reff = 1ω
- A. 80.0%
- B. 76.6%
- C. 66.7%
- D. 60.7%
Explanation
Efficiency = xV.R = number of pulleys = 6
ma = = = 4
Effiecieny = × 100 = 66.67%
12. Three 3ω resistance are connected in parallel what is the equivalent resistance?
- A. 1ω
- B. 9ω
- C. 3ω
- D. 0.33ω
Explanation
Resistor connected in a parallel have an equivalence given by= + +
= = = 1
Reff = 1ω
13.Which of the following instruments helps to maintain the correct humidity and temperature of a building?
Refrigerator is an appliance to keep things cold
Air blower is used to release air
Air conditioner is used to remove heat and maintain a stable temperature in an occupied space
- A. A compressor
- B. A refrigerator
- C. Air blower
- D. Air conditioner
Correct Answer: Option D
Explanation
Compressor is an instrument to supply air or other gas at increased pressureRefrigerator is an appliance to keep things cold
Air blower is used to release air
Air conditioner is used to remove heat and maintain a stable temperature in an occupied space
14. An element and its isotope only differ in the number of
- A. protons
- B. electrons
- C. ions
- D. neutrons
Explanation
Isotopy is due to difference in mass number, what causes the difference is the difference in the number of neutrons present
15.The thermal expansion of a solid is an advantage in
- A. Balance wheel of a watch
- B. Construction of steel rail lines
- C. Construction of large steel bridges
- D. Fitting of tyres on wheels
Explanation
Thermal expansion of a solid is majorly advantageous in the use of bimetallic strip in the balance of a watch so as not to lose time
16. The S.I unit of moment of a force is
HP = HQ, θP = 2θ,
mP = mQ
∴ HP = mQCPθP, also HQ = mQCQθQ
Since HP = HQ
∴ mPcPθP = mQcPθq
Putting in the conditions
mQ × cP × 2θQ = mQ × Î¸Q × cQ
∴ cP = cQ
=
= 1:1
V =
where Vo = peak voltage
∴ Vo = V × √2
= 240 × √2
= 339.5v
= 340v
B.
200 πrads
C.
50 πrads
D.
400 πrads
∴ since = 90o
∴ − 1
= 4 − 1
= 3
Phosphorous is a pentavalent element, so it will produce a o -type semi-conductor
From the diagram above, calculate the total current in the circuit
I =
Since the resistance are in parallel
= + +
= =
Reff = = 3.27
I = I1 + I2 + I3
= =
= 3.669A
I = 3.7A
where Z = mass number
A = atomic number
A = number of proton = number of electrons in a free state = 28
Z = number of protons + number of neutrons = 28 + 30 = 58
is the representation
- A. kgm
- B. µm
- C. Jm
- D. µm
Correct Answer: Option B
Moment = force × distance
= N × m
= Nm
Explanation
Moment of a force is the product of a force and the perpendicular distance from the line of action of the forceMoment = force × distance
= N × m
= Nm
17.A block and
tackle pulley arrangement has 6 pulleys in which an effort of 50N
supports a load of 200N, calculate the efficiency of the machine
- A. 80.0%
- B. 76.6%
- C. 66.7%
- D. 60.7%
18.Calculate the
light of the image formed by a pinhole camera of length 12cm used to
photograph an object 60cm away from the hole and 70cm high
m =
= 0.2
Also magnification m =
∴ Height of image = m × height of object
= 0.2 × 70
= 14cm
- A. 10 cm
- B. 16 cm
- C. 5 cm
- D. 14 cm
Explanation
Magnification =m =
= 0.2
Also magnification m =
∴ Height of image = m × height of object
= 0.2 × 70
= 14cm
19. When two
objects P and Q are supplied with the same quantity of heat, the
temperature change in P is observed to be twice that of Q. The mass of P
is half that of Q. The ratio of the specific heat capacity pf P to Q is
- A. 1:4
- B. 4:1
- C. 1:1
- D. 2:1
Explanation
H = mcθHP = HQ, θP = 2θ,
mP = mQ
∴ HP = mQCPθP, also HQ = mQCQθQ
Since HP = HQ
∴ mPcPθP = mQcPθq
Putting in the conditions
mQ × cP × 2θQ = mQ × Î¸Q × cQ
∴ cP = cQ
=
= 1:1
20. When the r.m.s value of a source of electricity supply is given as 240v, it means that the peak value of the supply is
- A. 240v
- B. 340v
- C. 480v
- D. 57600v
Explanation
The relationship between the peak value and r.m.s value of electricity supply is given asV =
where Vo = peak voltage
∴ Vo = V × √2
= 240 × √2
= 339.5v
= 340v
21 Which of the following operations can be used to convert an alternative current dynamo into a direct current dynamo
- A. number of turns in the coil is increased
- B. strength of the field magnet is increased
- C. slip rings are replaced with split ring cummutator
- D. coil is wound on a soft iron armature
Explanation
A d.c generator is one in which its current is allowed to flow in one direction even through it may vary in value an a.c generator can only be made to produce a d.c by replacing the two slip rings with a single split ring or commutator.22The net capacitance in the circuit above is- A. 80µF
- B. 6.0µF
- C. 4.0µF
- D. 2.0µF
Correct Answer: Option D
Explanation
For capacitance i n parallel, 2µF and 2µF are in parallel,
their equivalence is 2µF and 2µF = 4µF
The 4µF generated is now in series with the remaining 4µF.
The net capacitance for series connection is
= + = 1 + =
C =
= 2µF23. The instrument used to measure the pressure of a gas is- A. barometer
- B. thermometer
- C. hygrometer
- D. manometer
Explanation
Barometer is used to measure atmosphere pressure
Thermometer is used to measure temperature
Hygrometer is used to measure relative density of a liquid
Manometer is used to measure the pressure of a gas24.A man of mass 50kg ascends a flight of stains 5m high in 5 seconds. If acceleration due to gravity is 10msthe power expended is- A. 100w
- B. 200w
- C. 400w
- D. 500w
Correct Answer: Option D
Explanation
Power is the time rate of doing work
i.e power =
Since energy = mgH
∴ power =
=
= 500W
25. .A radio station broadcast at a frequency of 600KHZ. If the speed of light in air is 3 × 108ms. Calculate the wavelength of the radio waveA. 2.20 × 10mB. 5.0 × 10mC. 5.0 × 10mD. 11.8 × 10mCorrect Answer: Option B
Explanation
V = fλ
λ =
= = 500m
= 5 × 102m
N.B 600KHz Frequency = 600 × 103Hz
26 Which of the following is a scalar quantity?- A. Tension
- B. Weight
- C. Impulse
- D. Mass
Correct Answer: Option D
Explanation
Scalar quantity is a quantity with only magnitude, it has no direction
Tension, weight, impulse are vector quantities because they have direction. Mass is the only scalar quantity there27.Determine the focal length of a thin converging lens if the power is 5.0 dioptres- A. 0.1 m
- B. 0.2 m
- C. 2.0 m
- D. 2.5 m
Correct Answer: Option B
Explanation
Power of a lens =
f = focal length
f =
=
= 0.2m
28.A string of length 5cm is extended by 0.04m when a load of 0.8kg is suspended at the end. How far will it extend if a force of 16N is applied? [g = 10ms]- A. 0.04m
- B. 0.12m
- C. 0.01m
- D. 0.08m
Correct Answer: Option D
Explanation
From Hoke's Law, F = ke, K = Constant of Force
For he first case, Force = mg,
= 0.8 × 10 = 8N
∴ 8 = k × 0.04
k =
=
Since K is constant
For the second case, F = ke
F = 200 × e
∴ e =
=
= 0.08m
29. How can energy loss be minimized through Eddy-current?- A. By using high resistance wire
- B. By using insulated soft iron wires
- C. By using low resistance wires
- D. Bu using turns of wires
Correct Answer: Option A
Explanation
Eddy currents are produced by the varying flux cathode, the iron core of an equipment thus reducing efficiency due to power consumption. It can be reduced by laminating the core by breaking up the path of eddy current or by increasing the resistance of the core
Usage of insulated soft iron wire is to reduce hysteresis loss
Usage of low resistance wire (thick wire) is to reduce I2R loss
Usage of thick wire is to reduce leakage heat loss due to leakage of magnetic flux
Thus the correct answer is to use high resistance wire or thin wire
30From the diagram above, calculate the energy stored in the capacitor- A. 4.0 x 10
- B. 4.0 x 10J
- C. 8.0 x 10J
- D. 8.0 x 10
Explanation
c = 8µF, v = 10v
Energy stored =
= × (8 × 10− 6) × 102
= 4 × 10
31. A constant force of 5N acts for a 5 seconds on a mass of 5kg initially at rest. Calculate the final momentum- A. 125kgms−1
- B. 25kgms−1
- C. 15kgms−1
- D. 0kgms−1
Correct Answer: Option B
Explanation
Impulse = momentum
Impulse = Force (f) × time (t)
Momentum = mass (m) × velocity (v)
∴ Ft = Final momentum - initial momentum
FT = mv - mu
Since it is initially at rest u = 0
∴ 5 × 5 = mv − m(0)
25 = mv
∴ Final momentum = 25kgms32. I. Refraction II. Interference III. Diffraction Which of the above properties are common to all waves?- A. II and III only
- B. I, II and III
- C. I and II only
- D. I and III only
Correct Answer: Option B
Explanation
Refraction, Interference and diffraction are all properties of waves33. I. Refraction II. Interference III. Diffraction Which of the above properties are common to all waves?- A. II and III only
- B. I, II and III
- C. I and II only
- D. I and III only
Correct Answer: Option B
Explanation
Refraction, Interference and diffraction are all properties of waves34. Which of the following is correct about an electric cell?- A. Primary cell produces a large current for a long time
- B. Secondary cell has a very high internal resistance
- C. Primary cell has a very low internal resistance
- D. Secondary cell has a very low internal resistance
Correct Answer: Option D
Explanation
About electric cell
Primary cells are used up gradually often the cells are use and it can't be recharged
Secondary cells or accumulated can be recharged and used for a long period of time and their main advantage is that they have low internal resistance35.Which of the following is a semiconductor- A. copper
- B. silicon
- C. plastic
- D. Iron
Correct Answer: Option B
Explanation
Semi-conductor have an elecctric conductivity intermediate in value between that of a pure metal and a good insulator. Silicon is an example36. Which of the following surfaces will absorbs radiant heat energy heat?- A. white
- B. red
- C. black
- D. blue
Correct Answer: Option C
Explanation
A black solution is a better radiator of heat and allow a better absorber of heat.37. It is known that a neutron exists in a light atomic nucleusWhich of the following also exists in the nucleus?- A. An electron
- B. A β - particle
- C. β - particle
- D. proton
Correct Answer: Option D
Explanation
Nucleus of atom is made up of neutron and proton38.The instrument to measure the relative density of liquid is- A. thermometer
- B. hydrometer
- C. spring balance
- D. beaker
Correct Answer: Option BExplanation
Thermometer is used to measure temperature
Hydrometer is used to measure relative density of liquid.
Spring balance is used to measure the weight of an object
Beaker is used to measure or take volume of a liquid
39.What is the speed of a body vibrating at 50 cyclic per second- A. 100 πrads
Correct Answer: Option A
∴ 50 cycle = 2 Ï€ rad × 50 = 100 Ï€rad
∴ = angular speed = 50 cycles per seconds = 100 Ï€ rads
Explanation
1 cycle = 3600 = 2Ï€ rad∴ 50 cycle = 2 Ï€ rad × 50 = 100 Ï€rad
∴ = angular speed = 50 cycles per seconds = 100 Ï€ rads
40. The action of blotting paper on ink is due to
- A. diffusion
- B. osmosis
- C. capillarity
- D. surface tension
Explanation
Capillarity is the tendency of a liquid to rise or fall in a narrow tube and it explains why a blotting paper absorbs ink
41. When two
mirrors are placed at an angle of 900 to each other, how many images
will be formed when an object is placed in front of the mirrors
- A. 5
- B. 4
- C. 3
- D. 2
Explanation
When two mirror are inclined at an angle θ, the number of images formed, n = − 1∴ since = 90o
∴ − 1
= 4 − 1
= 3
42. If silicon is doped with phosphorus, what type of semiconductor material will be formed?
- A. Zener material
- B. P-n junction
- C. n-type
- D. p-type
Explanation
When silicon is doped with a trivalent atom. A p-type semi-conductor will be formed when silicon is doped with a pentavalent atom such as arsenic, a n-type semi-conductor will be formedPhosphorous is a pentavalent element, so it will produce a o -type semi-conductor
43..Calculate the angle of minimum deviation of a 60o prism of a refractive index [sin-10.75 = 49o]
- A. 38.00o
- B. 19.47o
- C. 16.25o
- D. 49o
Correct Answer: Option A
D = angle of minimum deviation
A = refractive angle of the prism
1.5 =
1.5 =
Sin (60 + D) = 1.5 * Sin 30
Sin (60 + D) = 0.75
(60 + D) = Sin-1 (0.75)
but Sin-1 (0.75) = 49o
Explanation
For a refractive index () =D = angle of minimum deviation
A = refractive angle of the prism
1.5 =
1.5 =
Sin (60 + D) = 1.5 * Sin 30
Sin (60 + D) = 0.75
(60 + D) = Sin-1 (0.75)
but Sin-1 (0.75) = 49o
(60 + D) = 49
60 + D = 2 * 49 = 98o
D = 98o - 60o
D = 38o
60 + D = 2 * 49 = 98o
D = 98o - 60o
D = 38o
44.What is the cost of running seven 40 W lamps and five 80 W la mps for 12 hours of the electrical energy cost N7.00kWk?
- A. N80.00
- B. N45.36
- C. N65.00
- D. N57.12
Correct Answer: Option D
Five 80W lamps = 5 × 80 = 400W
Total power = 280W + 400W
= 680W
= = 0.68KW
The kilowatt hour = 0.68 KW × 12 hrs
= 8.16 KWh
Cost is N 7 per KWh
So the cost of running them = 8.16KWh × N 7/KWh
= 57.12
Explanation
Seven 40W lamps = 7 × 40 = 280WFive 80W lamps = 5 × 80 = 400W
Total power = 280W + 400W
= 680W
= = 0.68KW
The kilowatt hour = 0.68 KW × 12 hrs
= 8.16 KWh
Cost is N 7 per KWh
So the cost of running them = 8.16KWh × N 7/KWh
= 57.12
45
![](https://myschool.ng/storage/classroom/6049880104_17_35.jpg)
From the diagram above, calculate the total current in the circuit
- A. 5.0A
- B. 3.7A
- C. 4.5A
- D. 4.0A
![](https://myschool.ng/storage/classroom/6049880104_17_35.jpg)
- A. 5.0A
- B. 3.7A
- C. 4.5A
- D. 4.0A
Correct Answer: Option B
Explanation
V = IR from ohms lawI =
Since the resistance are in parallel
= + +
= =
Reff = = 3.27
I = I1 + I2 + I3
= =
= 3.669A
I = 3.7A
- A. 10s
- B. 5s
- C. 4s
- D. 2s
- A. wave in closed pipe
- B. radio waves
- C. water waves
- D. sound waves
- A. Sinθ
- B. Cosθ
- C. Tanθ
- D.
- A. Sinθ
- B. Cosθ
- C. Tanθ
- D.
- A. 30cm3
- B. 40cm3
- C. 50cm3
- D. 20cm3
- A.
- B.
- C.
- D.
46.Calculate the time taken for a mango fruit that fall from the tree 20 m to the ground [g = 10 ms-2]
From equation of motion under gravity
H = ut ± gt2, It is falling so g is +ve
H = 0 + gt2
H = gt2
2H = gt2
= t2
t =
=
= √4
= 2s
Correct Answer: Option D
Explanation
u = , H = 20, g = 10From equation of motion under gravity
H = ut ± gt2, It is falling so g is +ve
H = 0 + gt2
H = gt2
2H = gt2
= t2
t =
=
= √4
= 2s
47.Which of the following is not a mechanical wave?
Explanation
Mechanical waves require material medium for their propagation only radio waves among the options docs require a material medium
48. The velocity ratio of an inclined plane where angle of inclination in θ is
The velocity ratio of an inclined plane where angle of inclination in θ is
Correct Answer: Option D
Explanation
![](https://myschool.ng/storage/classroom_answers/10587301011_sol_17_48.jpg)
V.R =
But Sinθ = =
therefore; = =
49.The volume of a fixed mass of gas is 10cm3 when its pressure is 400cmHg. Determine the volume of the gas when its pressure is 200cmHg.
Correct Answer: Option D
P1V1 = P2V2
V2 = =
= 20cm3
Explanation
Using boyle's lawP1V1 = P2V2
V2 = =
= 20cm3
50.Which of the following representations is correct for an atom X with 28 electrons and 30 neutrons?
Explanation
An atom can be represented thus,where Z = mass number
A = atomic number
A = number of proton = number of electrons in a free state = 28
Z = number of protons + number of neutrons = 28 + 30 = 58
is the representation
51. Which of the following is true of an electrical charge?
- A. Positive charge means deficit electrons
- B. Negative charge means excess of electrons
- C. electric current means movement of electrons
- D. All of the above
52.Which of the following is true of an electrical charge?
- A. Positive charge means deficit electrons
- B. Negative charge means excess of electrons
- C. electric current means movement of electrons
- D. All of the above
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