JAMB UTME - Physics - 1987 | Green Bridge CBT

Question 1 Report

A radioactive sample initially contains N atoms. After three half-lives the number of atoms that have disintegrated is

N

8

3N

8

5N

8

7N

8

Answer Details

N

\to

\frac{N}{2}

\to

\frac{N}{4}

\to

\frac{N}{8}

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Temperature And Its Measurement

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Question 2 Report

A load of 5N gives an extension of 0.56cm in a wire which obeys Hooke's law. What is the extension caused by a load of 20N?

1.12cm

2.14cm

2.24cm

2.52cm

Answer Details

\frac{F_{1}}{e_{1}}

=

\frac{F_{2}}{e_{2}}

$\frac{5}{0.56}$ = $\frac{20}{e_{2}}$

e2 = 2.24cm

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Elasticity

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Question 3 Report

Which of the following instruments has a pure tone?

guitar

vibrating strings

tuning fork

siren

Sound Waves

Work, Energy And Power

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Question 4 Report

The vacuum in a thermos flask helps to reduce heat transfer by?

convection and radiation

convection and conduction

conduction and radiation

radiation only

Heat Transfer

Temperature And Its Measurement

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Question 5 Report

Hot water is added to three times its mass of water at 10oC and the resultant temperature is 20oC. What is the initial temperature of the hot water?

100oC

80oC

50oC

40oC

Answer Details

Heat loss = heat gained

mh x ch x $θ$ h = mc x cc x $θ$ c

mh x ch x ( $θ$ - 20) = mc x cc x (20 - 10)

ch = cc ; mc = 3mh

therefore, $θ$ = 50oC

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Temperature And Its Measurement

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Question 6 Report

When two parallel wires carry currents in opposite directions, the force on either wire is

away from the other wire

zero, because the currents cancel each other

twice as much as when the currents are in the same direction

towards the other wire

Newton’s Laws Of Motion

Equilibrium Of Forces

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Question 7 Report

The distance between the fixed points of a centigrade thermometer is 20cm. What is the temperature when the mercury level is 4.5cm above the lower mark?

22.5oC

29.0oC

90.0oC

100.0oC

Answer Details

20cm .... 100oC

4.5cm .... $θ$

0cm ....0oC

$\frac{4.5 - 0}{20 - 0}$ = $\frac{0 - 0}{100 - 0}$

$θ$ = 22.5oC

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Temperature And Its Measurement

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Question 8 Report

If the angle of declination in a place is 10oE, calculate the true geographic bearing if the compass reads N40oE

N50oE

N40oE

N30oE

N25oE

Speed And Velocity

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Question 9 Report

A jet engine develops a thrust of 270Ns when the velocity of the exhaust gases relative to the engine is 300ms-1. What is the mass of the material ejected per second?

81.00kg

9.00kg

0.90kg

0.09kg

Answer Details

Thrust = force x time

thrust = $\frac{m (v - u)}{t}$ x $\frac{t}{1}$

270 = m(300 - 0)

m = 0.90kg

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Measurements And Units

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Question 10 Report

A galvanometer of resistance $20\,\Omega$ is to be provided with a shunt that $\frac{1}{10}$ of the whole current in a circuit passes through the galvanometer. The resistance of the shunt is

2.00

Ω

2.22

Ω

18.00

Ω

18.22

Ω

Answer Details

\frac{1}{10}

I x 20 =

\frac{9}{10}

I x Rs

Rs = 2.22 $Ω$

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Electrostatics

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Question 11 Report

Isotopes are nuclei which have

the same number of nuetrons and electrons

equal number of electrons and protons

the same atomic number but different number of neutrons

the same number of total particles

Structure Of The Atom (Nigeria Only)

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Question 12 Report

The fig above shows two connected bodies of masses M1 and M2 in equilibrium under gravity. The tension in the upper string is

(m1-m2)g

m1g

m2g

(m1+m2)g

Equilibrium Of Forces

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Question 13 Report

A pool of water appears to be 1.0m deep when viewed vertically from above. If the refractive index of water is 1.33, what is the actual depth of the pool?

0.750m

1.013m

1.330m

13.3000m

Answer Details

n =

\frac{real depth}{apparent depth}

1.33 = $\frac{real depth}{1}$

real depth = 1.33cm

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Refraction Of Light Through Plane And Curved Surfaces

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Question 14 Report

22,000J of heat is required to raise the temperature of 1.5kg of paraffin from 20oC to 30oC. Calculate the specific heat capacity of paraffin.

1466Jkg-1oC-1

2933Jkg-1oC-1

4400Jkg-1oC-1

5866Jkg-1oC-1

Answer Details

22,000 = 1.5 x c x (30 - 20)

c = 1466Jkg-1oC-1

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Heat Energy

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Question 15 Report

A wave has a frequency of 2Hz and a wavelength of 30cm. The velocity of the wave is

60.0ms-1

6.0ms-1

1.5ms-1

0.6ms-1

Answer Details

V = F

λ

= 2 x 0.3

= 0.6ms-1

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Production And Propagation Of Waves

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Question 16 Report

In which of the following are the substance arranged in descending order of their thermal conductivities?

copper, steel, glass

steel, copper, glass

steel, glass, copper

copper, glass, steel

Heat Transfer

Fluid At Rest

Gravitational Field

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Question 17 Report

As a result of air at the top of a barometer, the height of the mercury column is 73.5cm when it should be 75.0cm; the volume of the space above the mercury is 8.0cm3. Calculate the correct barometer height when the barometer reads 74.0cm and the volume of the space above the mercury is 6.0cm3.

72.0cm

74.5cm

75.1cm

76.0cm

Answer Details

Using, P1P1 = P2P2

(75 - 73.5) x 8 = (X - 74) x 6

X = 76cm

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Pressure

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Question 18 Report

A current of 0.5A flows through a resistor when connected to a 40-V battery. How much energy is dissipated in 2 minutes?

1200J

1500J

2400J

96000J

Answer Details

Electrical energy = IVT

= 0.5 x 40 x 2 x 60

= 2400J

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Read lesson note on Work, Energy And Power (WAEC)

Current Electricity

Work, Energy And Power

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Question 19 Report

If an object is placed in front of two mirrors inclined at 90o, how many images will be formed?

five

four

three

two

Answer Details

n =

\frac{360}{θ}

- 1

= 360 - 1

= 3 images

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Electrostatics

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Question 20 Report

he coefficient of static friction between a 40kg crate and concrete surface is 0.25. Find the magnitude of the minimum force needed to keep the crate stationary on the concrete base inclined at 45o to the horizontal. [G = 10ms-1]

400N

300N

283N

212N

Answer Details

momentum force = R5n

θ

-

μ

Rcos

θ

Fm = (40 x 10 x sin 45) - (40 x 10 x 0.25 x cos 45)

= 212N

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Friction

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Question 21 Report

An elevator of mass 4800kg is supported by a cable which can safely withstand a maximum tension of 60 000N. The maximum upward acceleration the elevator can have is

2.5ms-2

5.0ms-2

7.5ms-2

10.0ms-2

Answer Details

a =

\frac{F}{m}

= $\frac{60000 - (4800 \times 10)}{4800}$

= 2.5ms-2

Read lesson note on Newton’s Laws Of Motion (WAEC)

Newton’s Laws Of Motion

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Question 22 Report

Which of the following statements supports the assumption that light travels in straight lines?

light can be diffracted

a source of light produces distinct shadows of opaque objects

a source of light produces interference patterns on a suitably placed screen

light can be reflected

Light Energy

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Question 23 Report

In the above, a voltage V is applied across the terminals P and Q. The voltage across the 1 ohm resistor is

V/8

V/4

V/3

V/2

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Question 24 Report

The fig above represents the main sequence of energy conversion at Kainji dam. What is the efficiency of the system?

Q1/Q2

E/Q1

E/(Q1-Q2)

E/(Q1+Q2)

Heat Energy

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Question 25 Report

Four lenses are being considered for use as a microscope objective. Which of the following focal lengths is most suitable?

-5mm

+5mm

-5cm

+5cm

Electromagnetic Waves: Types Of Radiation In Electromagnetic Spectrum

Light Waves

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Question 26 Report

An object 3.0cm high is placed 60.0cm from a converging lens whose focal length is 20.0cm. Calculate the size of the image formed

0.5cm

1.5cm

2.0cm

6.0cm

Answer Details

F =

\frac{U V}{U + V}

20 = $\frac{60 \times V}{60 + V}$

V = 30cm

similarly, $\frac{U}{V}$ = $\frac{height of object}{height of image}$

$\frac{60}{30}$ = $\frac{3}{h}$

h = 1.5cm

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Read lesson note on Measurements And Units (JAMB)

Light

Measurements And Units

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Question 27 Report

Which of the following phenomena explains the fact that a house whose roof is coated with white paint will be cooler in the hot season than one coated with black paint ?

conduction

convection

refraction

reflection

Pressure

Simple A.C Circuits

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Question 28 Report

The direction of the magnetic field at a point in the vicinity of a bar magnet is

always towards the north pole of the magnet

always away from the south pole of the magnet

along the line joining the point to the neutral point

in the direction the north pole of a compass needle would point

Magnetic Field (Part 1)

Electromagnetic Field (Part 2)

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Question 29 Report

A man walks 8km north and then 5km in a direction 60o east of north. Find the distance from his starting point

11.36km

12.36km

13.00km

14.36km

Answer Details

R =

\sqrt{5^{2} + 8^{2} - 2 \times 5 \times 8 \times c o s 120^{o}}

R = $\sqrt{129}$

= 11.36km

Read lesson note on Scalars And Vectors (JAMB)

Read lesson note on Position, Distance And Displacement (WAEC)

Scalars And Vectors

Position, Distance And Displacement

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Question 30 Report

A body rolls down a slope from a height of 100m. its velocity at the foot of the slope is 20ms-1. What percentage of its initial potential energy is converted into kinetic energy? [g = 10ms-1]

40%

35%

20%

15%

Answer Details

P.E = mgh = 1000m joules

K.E = $\frac{1}{2}$ mv2 = 200m joules

%converted = $\frac{200 m}{1000 m}$ x 100

= 20%

Read lesson note on Measurements And Units (JAMB)

Measurements And Units

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Question 31 Report

A ray of light is incident at an angle of 30o on one top surface of a parallel-sided glass block of refractive index 1.5. The ray finally emerges from the lower surface. What is the angular deviation of the emergent ray?

60o

39o

28o

0o

Reflection Of Light At Plane And Curved Surfaces

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Question 32 Report

When the length I of a piece of wire under constant tension is varied, the relationship of the frequency of the vibration $ \alpha $/ is

f

α

/

f

α \frac{1}{I^{2}}

f

α \sqrt{I}

f

1

Answer Details

F =

\frac{1}{2 L} \sqrt{\frac{T}{m}}

Read lesson note on Newton’s Laws Of Motion (WAEC)

Read lesson note on Equilibrium Of Forces (WAEC)

Newton’s Laws Of Motion

Equilibrium Of Forces

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Question 33 Report

Which of the following units is equivalent to kgms-1?

Ns-1

Nms-1

Ns

Js-1

Answer Details

kgms-1 =

\frac{m a s s}{d i s t a n c e}

since, F = ma = kgms-1 = N

kgms-1 = Ns

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Measurements And Units

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Question 34 Report

In the figure above, M and N are insulated metal spheres in contact. A negatively charged ebonite rod P is I brought near M. When M and N are Separated and the rod is taken away, which of the following statements is correct

both M and N have acquired negative charges

both M and N have acquired positive charges

M has acquired negative charge and N positive charge

N has acquired negative charge and M positive charge

Electrostatics

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Question 35 Report

When a transformer has more secondary windings than primary windings, it

has a smaller secondary current

has a greater power output

is a step-down transformer

increases the total energy output

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Question 36 Report

Which of the following statements is TRUE of photoelectric effect?

it cannot occur in liquids

the energy of the emitted electrons is independent of the work function of the surface

the energy of the emitted electron depends on the wavelength of the incident light

the greater the intensity of the incuident light, the greater the incident of the emitted electron

Structure Of The Atom (Nigeria Only)

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Question 37 Report

A 50kg block is dropped from a point 10cm above as shown in the fig above. if the force constant of the spring is 4.0 x 104Nm-1, find the maximum compression of the spring [g = 10ms-2]

1.25m

0.50m

0.25m

0.05m

Equilibrium Of Forces

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Question 38 Report

he lowest note emitted by a stretched string has a frequency of 40Hz. How many overtones are there between 40Hz and 150Hz?

1

2

3

4

Answer Details

In stretched strings the overtones are in odd multiple of Fo.

F1 = 3Fo

= 3 x 40 = 120Hz

F2 = 5Fo

= 5 x 40

= 200Hz

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Propagation Of Sound Waves

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Question 39 Report

The velocity time graph above describes the motion of a particle between two points P and Q. What is the distance between P and Q?

17.0m

18.0m

22.5m

30.0m

Motion

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Question 40 Report

The mechanical advantage (MA) of an inclined plane depends on

its length

its height

the product of its length and height

the ratio of its length to its height

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Question 41 Report

A cube of side 10cm and mass 0.5kg floats in a liquid with only $ \frac{1}{5} $ of its height above the liquid surface. What is the relative density of the liquid?

0.125cm-1

0.250gcm-1

0.625cm-1

2.500cm-1

Answer Details

Height below liquid = 1 -

\frac{1}{5}

=

\frac{4}{5}

volume of cube = 103cm3

volume of liquid displaced = $\frac{4}{5}$ x 1000

= 800cm3

density of liquid displaced;

= $\frac{500}{800}$

= 0.625cm-1

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Read lesson note on Quantity Of Heat (JAMB)

Light Energy

Simple Harmonic Motion

Quantity Of Heat

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Question 42 Report

Two capacitance of $6\,\mu\text{F}$ and $8\,\mu\text{F}$ are connected in series. What additional capacitance must be connected in series with this combination to give a total of $3\,\mu\text{F}$

3

μ

F

16

μ

F

24

μ

F

30

μ

F

Answer Details

3 =

\frac{6 \times 8 \times c}{(6 \times 8) + (6 \times c) + (8 \times c}

therefore, C = 24 $μ$ F

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Capacitors

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Question 43 Report

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 behavior is due to

friction

viscosity

surface tension

evaporation

Friction

Temperature And Its Measurement

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Question 44 Report

What type of reaction is represented by the following scheme?

\[ {}^{2}_{1}X + {}^{2}_{1}Y + {}^{3}_{2}Z + {}^{1}_{0}n + \text{energy} \]

Fusion reaction

Fission reaction

Chain reaction

Radioactive decay

Elementary Modern Physics

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Question 45 Report

A constant force of 40N acting on a body initially at rest gives an acceleration of 0.1ms-2 for 4s. Calculate the work done by the force

8J

10J

32J

160J

Answer Details

X = ut +

\frac{1}{2}

at2

= (0 x 4) + ( $\frac{1}{2}$ x 0.1 x 4 x 4)

= 0.8m

workdone = force x distance

= 40 x 0.8

= 32J

Read lesson note on Work, Energy And Power (WAEC)

Read lesson note on Equilibrium Of Forces (WAEC)

Work, Energy And Power

Equilibrium Of Forces

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Question 46 Report

A boat at anchor is rocked by waves whose crest are 100m apart and whose velocity is 25ms-1. At what interval does the wave crest reach the boat?

2500.00s

75.00s

4.00s

0.25s

Answer Details

Distance between the boat and crest = 100m

time = $\frac{100}{25}$

= 4sec

View Answer

Question 47 Report

The length of a side of a metallic cube at 20oC is 5.0cm. Given that the linear expansivity of the metal is 4.0 x 10-5k-1, find the volume of the cube at 120oC .

126.50cm3

126.25cm3

126.00cm3

125.00cm3

Answer Details

Y =

\frac{V_{2} - V_{1}}{V_{1} \times θ}

3 x 4 x 10-5 = $\frac{V_{2} - 125}{125 \times (120 - 20)}$

V2 = 126.50cm3

Read lesson note on Temperature And Its Measurement (JAMB)

Temperature And Its Measurement

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Question 48 Report

Calculate the amount of heat required to convert 2kg of ice at 2oC to water at 0oC. [specific heat capacity of ice = 2090Jkg-1oC-1, specific latent heat of fusion of ice = 333kJkg-1]

666J

8360J

666 000J

674 360J

Answer Details

Q = mL + mc

θ

= (2 x 333000) + (2 x 2090 x 2)

= 674 360J

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Quantity Of Heat

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