WAEC - Physics (2018)

1
The S.I unit for sound energy is
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(D)
J
2
The general definition of elastic modulus is
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(A)
\(\frac{stress}{strain}\)
3

The diagram above illustrates a simple barometer. Which distance measures the atmospheric pressure?
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(B)
QR
4
The property of a body to remain at rest or to continue in uniform motion in a straight line is called
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(B)
Inertia
5
During a training session, two footballers pass a ball repeatedly between each other. The 'to and fro' motion of the ball is not simple harmonic because the

I. Acceleration of the ball is not directed towards a fixed point

II. Restoring force is not directed towards the centre

III. Acceleration of the ball is not directly proportional to the displacement from a fixed point

Which of the statements above are correct?
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(A)
I and III only
6
A dam is able to hold a large quantity of water because its wall is
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(C)
thickest at the bottom
7
A body of mass m moving around a circle of radius r with a uniform speed v experiences a centripetal force F. The work done by the centripetal force on it is
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(B)
zero
8

A block is acted upon by TWO horizontal forces as illustrated in the diagram above. The block accelerates at 1.5\(ms^{-2}\). Calculate the mass of the block.
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(A)
6kg
9
Which of the following quantities are dimensionally independent?

I. Dielectric constant II. Momentum III. Efficiency IV. Refractive index
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(D)
I, III and IV
10
A body is projected with an initial velocity u at angle \(\theta\) to the horizontal. If \(R_{max}\) is the maximum range of the projectile, what does the relation \(\frac{u^{2}}{R_{max}}\) represent?
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(B)
Acceleration due to gravity
11
An object at rest is said to possess
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(A)
potential energy
12
According to Newton's law of cooling, the heat energy lost per unit area of a body depends on the

I. Surface area

II. Nature of the surface

III. Temperature of the surface

IV. Excess temperature over the surroundings
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(C)
I,II and III
13

The graph of density against temperature for water is correctly illustrated by
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(C)
III
14
A football is kicked at an angle of 45° to the horizontal over a defense line up with a velocity of 15\(ms^{-1}\). Calculate the magnitudeof horizontal velocity of the ball at its highest point [Neglect friction, g = 10\(ms^{-2}\)].
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(C)
10.6\(ms^{-1}\)
15
The ice point on the absolute scale of temperature is
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(A)
0K
16
Which of the following factors does not increase the rate of evaporation of water in a lake?
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(A)
Increase in the pressure of the atmosphere
17
The bob of a simple pendulum takes 8.0s to complete 10 oscillations. Determine the frequency of oscillation of the bob.
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(B)
1.25Hz
18

The diagram above illustrates the mercury-in-glass thermometer used for determining the temperature of a room. Use the data on it to determine the room temperature.
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(D)
30.0°C
19
Frequency is measured in
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(C)
hertz
20
Which of the following electromagnetic waves is most energetic?
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(C)
Gamma rays
21
Rainbow formation is a natural phenomenon illustrating that white light
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(D)
is dispersed into its constituent colours after rainfall
22

The lens illustrated above can best be described as a
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(B)
plano-convex
23
Two plane mirrors are inclined to each other such that an object placed between them has 11 images. Determine the angle of inclination
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(A)
30°
24
The pitch of a note is not affected by
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(D)
amplitude of sound wave
25
When two flat plate conductors are arranged in such a way that they possess equal and opposite charges seperated by a dielectric, they form a/an
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(C)
capacitor
26

Which electrical device is illustrated above?
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(C)
d.c. generator
27
A simple barometer is constructed using a liquid \(Q_{1}\) of density 16.2\(g/cm^{3}\). Calculate the least lenth of the tube to be used to measure pressure of 1.5atm. [Density of mercury = 13.6\(g/cm^{3}\), 1atm = 76.0 cm of Mercury]
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(D)
638mm
28

A bar AB is balanced horizontally on two knife edges as illustrated as in the diagram above. Determine the weight of the bar.
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(C)
40.0N
29
To obtain a virtual, erect and magnified image from a thin converging lens, an object must be placed
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(A)
between the focus and the lens
30

The diagram above represents a transverse travelling wave. Which two points are 180° out of phase?
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(D)
D and H
31
Two objects P and Q of masses 100kg and 20kg respectively are 1.2m apart on a horizontal surface. Calculate the net gravitational force acting on Q. \([G= 6.67 \times 10^{-11} Nm^{2}kg^{-2}]\)
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(D)
\(9.26\times 10^{-8} N\) towards Q
32
The primary of a transformer has 100 turns and its secondary has 200 turns. If the voltage at the primary is 100V, determine the voltage at the secondary.
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(C)
200V
33

In the diagram illustrated a block of mass M is at rest on a plane inclined at an angle \(\theta\) to the horizontal. As \(\theta\) increases, the velocity ratio of the plane
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(B)
decreases
34
When the speed of a car is halved, its kinetic energy is
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(B)
quartered
35
A wire of length 400cm is stretched between two fixed points. When plucked, its fundamental frequency is 150Hz. Calculate the speed of the wave produced.
Trả lời
(C)
1200\(ms^{-1}\)
36

The diagram above illustrates a waveform. Determine the number of wavelengths in it
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(C)
2\(\frac{1}{2}\)
37
A resistor with fixed resistance value is called a
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(B)
standard resistor
38
Which of the following statements is not an advantage of an alkaline accumulator?
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(A)
The electrolyte does not need attention
39

The diagram above illustrates the wire connections to a three-pin plug. The wires P, Q and R respectively are:
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(B)
neutral, earth and live
40
Which of the following statements about parallel plate capacitors is/are correct?

I. Capacitance of the capacitor is inversely proportional to the distance between the plates

II. Capacitors can filter a.c signals from d.c

III. Capacitors can store charges
Trả lời
(D)
I, II and III
41

The circuit contains three ammeters A1, A2 and A3 with readings of A2 and A3 shown as indicated in the diagram. Determine the reading of A1.
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(B)
3A
42
Which of the following statements about magnetic lines of force is not correct? They
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(D)
intersect one another
43
In which of the following activities is an induction coil not useful?
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(D)
A.C. power transmission
44
In a series R-L-C circuit, R = 10\(\Omega\), \(X_{c}\)= 4\(\Omega\) and \(X_{L}\) = 9\(\Omega\). The impedance of the circuit is
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(D)
11.2\(\Omega\)
45

A student uses two compass needles to investigate the magnetic field around a bar magnet. Which of the following diagrams show the correct directions of the needles?
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(B)
B