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.
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(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
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(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