Q7103.A glass bottle of initial volume $2 \times 10^4 \mathrm{cm}^3$ is heated from $20^{\circ}\mathrm{C}$ to $50^{\circ}\mathrm{C}$. If the linear expansivity of glass is $9 \times 10^{-6} \mathrm{K}^{-1}$, the volume of the bottle at $50^{\circ}\mathrm{C}$ is
Q7111.The diagram above shows a stationary wave of wavelength $40 \mathrm{cm}$ in a closed tube. The length $l$ of the resonating air column is
A$10 \mathrm{cm}$
B$20 \mathrm{cm}$
C$30 \mathrm{cm}$
D$40 \mathrm{cm}$
Correct Answer: C
For a closed pipe, the first resonance has length $\dfrac{\lambda}{4}$, the second has $\dfrac{3\lambda}{4}$. The diagram likely shows the second resonance. $l = \dfrac{3 \times 40}{4} = 30 \mathrm{cm}$.
JAMB (UTME)
Physics
2014
Q7112.An object is placed $10 \mathrm{m}$ from a pinhole camera of length $25 \mathrm{cm}$. Calculate the linear magnification.
Q7113.The focal length of a concave mirror is $2.0 \mathrm{cm}$. If an object is placed $8.0 \mathrm{cm}$ from it, the image is at
A$2.7 \mathrm{m}$
B$2.0 \mathrm{m}$
C$2.3 \mathrm{m}$
D$2.5 \mathrm{m}$
Correct Answer: A
$\dfrac{1}{f} = \dfrac{1}{u} + \dfrac{1}{v}$. $\dfrac{1}{2} = \dfrac{1}{8} + \dfrac{1}{v}$. $\dfrac{1}{v} = \dfrac{1}{2} - \dfrac{1}{8} = \dfrac{3}{8}$. $v = \dfrac{8}{3} = 2.67 \mathrm{cm} \approx 2.7 \mathrm{cm}$. The answer key A is correct but the unit should be $\mathrm{cm}$, not $\mathrm{m}$.
JAMB (UTME)
Physics
2014
Q7114.In a compound microscope, the objective and the eye piece focal lengths are
ALong
BShort
CThe same
DAt infinity
Correct Answer: B
Both the objective and eyepiece of a compound microscope have short focal lengths.
JAMB (UTME)
Physics
2014
Q7115.When a telescope is in normal use, the final image is at
AThe focus
BThe radius of curvature
CThe near point
DInfinity
Correct Answer: D
In normal adjustment, the final image is at infinity (relaxed eye).
JAMB (UTME)
Physics
2014
Q7116.When a negatively charged rod is brought near the cap of a charged gold leaf electroscope which has positive charges, the leaf
ACollapses
BCollapses and diverges again
CDiverges
DRemains the same
Correct Answer: A
The negative rod attracts positive charges to the cap, reducing the charge on the leaves, causing them to collapse.
JAMB (UTME)
Physics
2014
Q7117.What charge is stored in a $0.1 \mathrm{F}$ capacitor when a $10 \mathrm{V}$ supply is connected across it?
A$1 \mathrm{C}$
B$5 \mathrm{C}$
C$4 \mathrm{C}$
D$2 \mathrm{C}$
Correct Answer: A
$Q = CV = 0.1 \times 10 = 1 \mathrm{C}$.
JAMB (UTME)
Physics
2014
Q7118.Calculate the effective capacitance of the circuit above.
A$1 \mu\mathrm{F}$
B$2 \mu\mathrm{F}$
C$3 \mu\mathrm{F}$
D$4 \mu\mathrm{F}$
Correct Answer: B
The circuit has three $2 \mu\mathrm{F}$ capacitors in parallel and one $3 \mu\mathrm{F}$ capacitor in series. The parallel combination gives $6 \mu\mathrm{F}$. The series combination of $6 \mu\mathrm{F}$ and $3 \mu\mathrm{F}$ gives $\dfrac{6 \times 3}{6 + 3} = \dfrac{18}{9} = 2 \mu\mathrm{F}$.
JAMB (UTME)
Physics
2014
Q7119.The maximum power transfer occurs in a cell when the external resistance is
ATwice the internal resistance of the cell
BThe same as the internal resistance of the cell
CGreater than the internal resistance of the cell
DLess than the internal resistance of the cell
Correct Answer: B
Maximum power transfer occurs when external resistance equals internal resistance.
JAMB (UTME)
Physics
2014
Q7120.If a metal wire $4 \mathrm{m}$ long and cross-sectional area $0.8 \mathrm{mm}^2$ has a resistance of $60 \Omega$, find the resistivity of the wire.
A$5.3 \times 10^{-7} \Omega\mathrm{m}$
B$3.0 \times 10^{-5} \Omega\mathrm{m}$
C$1.2 \times 10^{-6} \Omega\mathrm{m}$
D$3.2 \times 10^{-6} \Omega\mathrm{m}$
Correct Answer: C
$R = \dfrac{\rho L}{A}$. $\rho = \dfrac{RA}{L} = \dfrac{60 \times 0.8 \times 10^{-6}}{4} = 1.2 \times 10^{-5} \Omega\mathrm{m}$. The answer key C is incorrect; the correct answer is $1.2 \times 10^{-5} \Omega\mathrm{m}$.
JAMB (UTME)
Physics
2014
Q7121.A circuit has a resistance of $200 \Omega$. The resistance of the circuit can be reduced to $120 \Omega$ when
Aa resistor of $300 \Omega$ is connected in parallel
Ba resistor of $300 \Omega$ is connected in series
Ca resistor of $120 \Omega$ is connected in parallel
Da resistor of $120 \Omega$ is connected in series.
Electrical energy is measured in kilowatt-hours (kWh).
JAMB (UTME)
Physics
2014
Q7123.What is the best method of demagnetizing a steel bar magnet?
AHammering
BHeating it
CRough handling it
DSolenoid method
Correct Answer: D
The solenoid method (using a decreasing alternating current) is the best way to demagnetize a magnet.
JAMB (UTME)
Physics
2014
Q7124.The magnitude of the angle of dip at the equator is
A$360^{\circ}$
B$0^{\circ}$
C$90^{\circ}$
D$180^{\circ}$
Correct Answer: B
At the equator, the magnetic field is horizontal, so the angle of dip is $0^{\circ}$.
JAMB (UTME)
Physics
2014
Q7125.The diagram above is that of
Aa step-up transformer
Ba step-down transformer
Can auto transformer
Dan oil transformer.
Correct Answer: A
The primary coil has fewer turns than the secondary coil, so it is a step-up transformer.
JAMB (UTME)
Physics
2014
Q7126.The electromotive force in the secondary winding is
Aincreasing
Breducing
CStabilizing
DVarying
Correct Answer: D
In a transformer, the induced e.m.f. in the secondary winding varies with time (a.c.).
JAMB (UTME)
Physics
2014
Q7127.What type of reaction is represented by the equation $^2_1X + ^2_1X \rightarrow ^3_2Y + ^1_0n + \text{energy}$?
AFusion reaction
BFission reaction
CChain reaction
DRadioactive decay
Correct Answer: A
Two light nuclei combine to form a heavier nucleus, releasing energy. This is nuclear fusion.
JAMB (UTME)
Physics
2014
Q7128.When an atom undergoes a beta decay, the atomic number of the nucleus
ARemains unchanged
BDecreases by one
CIncreases by one
DBecomes zero
Correct Answer: C
In beta decay, a neutron converts to a proton, so the atomic number increases by one.
JAMB (UTME)
Physics
2014
Q7129.Calculate the mass of the copper deposited during electrolysis when a current of $4 \mathrm{A}$ passes through a copper salt for $2$ hours. [ece of Copper $Z = 3.3 \times 10^{-7} \mathrm{kgC}^{-1}$]
Q7130.Which gas produces a pink coloured light in a discharge tube?
AMercury
BArgon
CAir
DNeon
Correct Answer: D
Neon produces a characteristic pink/red glow in a discharge tube.
JAMB (UTME)
Physics
2014
Q7131.When $^{210}_{82}\mathrm{Pb}$ decays to $^{206}_{80}\mathrm{Pb}$, it emits
Atwo alpha and two beta particles
Ban alpha particle
Cone beta particle
Done alpha and one beta particle
Correct Answer: D
Mass number decreases by 4 (one alpha particle), atomic number decreases by 2. To get from 82 to 80, one alpha emission (82 to 80) is sufficient, but mass number goes from 210 to 206 (4 units). The question asks what it emits. One alpha particle accounts for the mass change and the atomic number change from 82 to 80. The answer key D is incorrect. The correct answer is B (an alpha particle).
JAMB (UTME)
Physics
2014
Q7132.In a common emitter configuration, the output voltage is through the
AResistor
BBase
CCollector
DEmitter
Correct Answer: C
In a common emitter amplifier, the output is taken from the collector.
JAMB (UTME)
Physics
2014
Q7133.Which of the graphs below shows the characteristic of an i-v transistor?
A[Graph A]
B[Graph B]
C[Graph C]
D[Graph D]
Correct Answer: C
The characteristic curve for a transistor shows collector current increasing with collector-emitter voltage and then flattening out. Graph C represents this.
Instruction
JAMB Physics 2015
JAMB (UTME)
Physics
2015
Q7134.A piece of rubber 10cm long stretches 6mm when a load of 100N is hung from it. What is the strain?
A$6 \times 10^{-3}$
B$6$
C$60$
D$6.0 \times 10^{-3}$
Correct Answer: D
Strain $= \dfrac{\text{Extension}}{\text{Original length}} = \dfrac{6 \mathrm{mm}}{10 \mathrm{cm}} = \dfrac{0.6 \mathrm{cm}}{10 \mathrm{cm}} = 0.06 = 6.0 \times 10^{-2}$. The answer key D is incorrect; the correct answer is $6.0 \times 10^{-2}$, which is not listed. (Note: If extension was 0.6mm, strain would be $6.0 \times 10^{-3}$).
JAMB (UTME)
Physics
2015
Q7135.The diagram above shows the lens arrangement in
Acompound microscope
Ba binocular
Can astronomical telescope
Da periscope
Correct Answer: C
The diagram shows two convex lenses arranged as an astronomical telescope.
JAMB (UTME)
Physics
2015
Q7136.What is the total resistance in the diagram below?
A$5 \Omega$
B$25 \Omega$
C$15 \Omega$
D$35 \Omega$
Correct Answer: B
The diagram shows resistors in series. $R = 5 + 10 + 10 = 25 \Omega$.
JAMB (UTME)
Physics
2015
Q7137.A body of mass 6kg rests on an inclined plane. The normal reaction R and the limiting frictional force F as shown in the diagram (Fig. 2). If F is 30N and $g = 10 \mathrm{ms}^{-2}$, then the angle of inclination $\theta$ is
Polarization is a property of transverse waves only. Longitudinal waves cannot be polarized.
JAMB (UTME)
Physics
2015
Q7140.A device that converts sound energy into electrical energy is
Athe horn of a motor car
Bthe telephone earpiece
Ca loudspeaker
Da microphone.
Correct Answer: D
A microphone converts sound energy into electrical energy.
JAMB (UTME)
Physics
2015
Q7141.A good calorimeter should be of
Alow specific heat capacity and low heat conductivity
Bhigh specific heat capacity and low heat conductivity
Chigh specific heat capacity and high heat conductivity
Dlow specific heat capacity and high heat conductivity.
Correct Answer: A
A good calorimeter should have low specific heat capacity (so it absorbs little heat) and low heat conductivity (to minimize heat loss to surroundings).
JAMB (UTME)
Physics
2015
Q7142.Which of the following is most strongly deflected by a magnetic field?
A$\beta$-particles
B$\alpha$-particles
C$\gamma$-rays
DX-rays
Correct Answer: A
Beta particles have the smallest mass among the charged particles listed, so they are most strongly deflected by a magnetic field.
JAMB (UTME)
Physics
2015
Q7143.If a beaker is filled with water, it is observed that the surface of the water is not horizontal at the glass-water interface. This behaviour is due to
Afriction
Bsurface tension
Cviscosity
Devaporation
Correct Answer: B
Surface tension causes the meniscus (curved surface) at the glass-water interface.
JAMB (UTME)
Physics
2015
Q7144.A dynamo primarily conducts
Apotential energy into kinetic energy
Belectrical energy into kinetic energy
Cmechanical energy into electrical energy
Dkinetic energy into potential energy
Correct Answer: C
A dynamo (generator) converts mechanical energy into electrical energy.
JAMB (UTME)
Physics
2015
Q7145.A particle is injected perpendicularly into an electric field. It travels along a curved path as depicted in the figure 3. The particle is
Agamma ray
Ba proton
Ca neutron
Dan electron
Correct Answer: D
The particle is deflected towards the positive plate, so it must be negatively charged (an electron).
JAMB (UTME)
Physics
2015
Q7146.In which of the following diagrams is the length of the tube equal to one wavelength?
A[Diagram A]
B[Diagram B]
C[Diagram C]
D[Diagram D]
Correct Answer: A
For a stationary wave in a tube open at both ends, one wavelength corresponds to two loops (one full wave). The diagram A shows a full wave pattern.
JAMB (UTME)
Physics
2015
Q7147.A calibrated potentiometer is used to measure the e.m.f. of a cell because the
Ainternal resistance of a cell is small compared with that of the potentiometer
Bpotentiometer takes no current from the cell
Cpotentiometer has a linear scale
Dresistance of the potentiometer is less than that of a voltmeter
Correct Answer: B
A potentiometer measures the e.m.f. of a cell by drawing no current from it at the balance point, so it measures the true e.m.f.
JAMB (UTME)
Physics
2015
Q7148.Which of the following is a vector?
AElectric charge
BElectric potential difference
CElectric field
DElectrical capacitance.
Correct Answer: C
Electric field is a vector quantity (it has both magnitude and direction).
JAMB (UTME)
Physics
2015
Q7149.The photocell works on the principle of the
Avoltaic cell
Bphotographic plate
Cemission of protons by incident electrons
Demission of electrons by incident radiation
Correct Answer: D
A photocell works on the principle of the photoelectric effect, where electrons are emitted by incident radiation.
JAMB (UTME)
Physics
2015
Q7150.When an atom loses or gains a charge, it becomes
Aan ion
Ban electron
Ca neutron
Da proton
Correct Answer: A
An atom that loses or gains electrons becomes an ion.