WAEC - Physics (2012)

1
The derived unit of pressure can be expressed as
پاسخ دهید
(B)
kg m^-1s^-2
2
The diagram above illustrates trapped air in a syringe placed in water that is gradually heated. It is observed that the piston rises as the temperature of the water rises. Which of the following statements explains this observation?
پاسخ دهید
(B)
molecules of trapped air expands more
3
Which of the following devices is used to determine the relative density of an acid?
پاسخ دهید
(B)
hydrometer
4
A block of wood of density 0.6 gcm\(^{-3}\), weighing 3.06N in air, floats freely in a liquid of density 0.9 gcm\(^{-3}\). Calculate volume of the portion immersed (g = 10ms\(^{-2}\))
پاسخ دهید
(B)
340cm³
5
A metal ball of weight W falls through a column of glycerine of viscosity V. If the ball experiences an upthrust U and terminal velocity is attained, then
پاسخ دهید
(B)
W = U + V
6
The movement of fluid up or down a narrow tube is
پاسخ دهید
(C)
capillarity
7
Which of the following substances is the most volatile at room temperature?
پاسخ دهید
(C)
petrol
8
A bird flies at 10ms\(^{-1}\) for 3s, 15ms\(^{-1}\) for 3s and 20 ms\(^{-1}\) for 4s. Calculate the bird's average speed
پاسخ دهید
(C)
15.5 ms^-1
9
The time of flight for a projectile motion is given by the expression
پاسخ دهید
(C)
\(\frac{2U sin \theta}{g}\)
10
An object is dropped from the top of a tower. If it takes 4s for it to reach the ground, calculate the height of the tower.(g = 10 ms-2, ignore air resistance)
پاسخ دهید
(C)
80m
11
When a body is slightly tilted, it is found that its centre of gravity is slightly raised. What is the state of equilibrium of the body?
پاسخ دهید
(B)
stable
12
A simple pendulum makes 50 oscillations in one minute. Determine its period of oscillation
پاسخ دهید
(C)
1.20s
13
The tendency for a stationary body to continue to remain at rest when a force is applied to it is known as
پاسخ دهید
(C)
inertia
14
A resultant force of magnitude 15N acts on a body of mass 250g. Calculate the magnitude of the acceleration
پاسخ دهید
(D)
60.00ms^-2
15
A girl stands on a scale in a lift. If the reading on the scale is less than her weight, then the lift is moving
پاسخ دهید
(D)
downward with uniform acceleration
16
The S.I unit of heat is
پاسخ دهید
(A)
joule
17
A body is pulled through a distance of 500m by a force of 20N. If the power developed is 0.4kW, calculate the time for which the force acts
پاسخ دهید
(B)
25.0s
18
A metal sheet of area 100cm\(^2\) was heated through 70°C. Calculate its new area if the linear expansivity of the metal is 0.000017K\(^{-1}\).
پاسخ دهید
(C)
100.24cm²
19
The thermopile is a device for detecting
پاسخ دهید
(B)
radiant energy
20
In the formation of sea breeze. wind blows from
پاسخ دهید
(D)
sea to land
21
A piece of copper of mass 20g at a temperature of 110°C was dropped into a mixture of ice and water at 0°C. If the final steady temperature of the mixture is 0°C . Calculate the amount of ice that melted [Specific heat capacity of copper = 0.4 Jg\(^{-1}\)K\(^{-1}\), specific latent heat of fusion of ice = 330Jg\(^{-1}\)]
پاسخ دهید
(D)
2.70g
22
Which of the following factors decreases the rate of evaporation of a liquid?
پاسخ دهید
(A)
increase in pressure over the liquid
23
When two waves are superimposed on each other, the following occurrences are possible, except
پاسخ دهید
(D)
dispersion
24
Which of the following properties of waves is exclusive to transverse waves?
پاسخ دهید
(D)
polarization
25
An object of height 2.5cm is places 20cm from a convex mirror of focal length 10cm. Calculate the height of its image.
پاسخ دهید
(A)
2.5 cm
26
A ray of light passes from air to water to glass to air. Given that the refractive index for light passing from air to water is \(\frac{4}{3}\) and air to glass is \(\frac{3}{2}\), calculate the refractive index of glass relative to water
پاسخ دهید
(D)
1.13
27
An object is placed at a point X between the focal point F and the optical centre C of a diverging lens. If F is the focal point on the other side of the lens, the image of the object is formed between
پاسخ دهید
(B)
X and C
28
An object is placed 10cm from a converging lens of foal length 15cm. Calculate the magnification of the image formed
پاسخ دهید
(A)
3.0
29
A telescope is said to be in normal adjustment when the
پاسخ دهید
(D)
objective focal point coincides wih that of the eyepiece
30
The sound heard by a person after the reflection of the sound generated by him is called
پاسخ دهید
(C)
echo
31
Which of the following sets of coloured light is/are secondary colours i. Red, Blue and green ii. Blue, cyan and magneta iii. Green, Magenta and yellow, IV Yellow, Cyan and Magenta
پاسخ دهید
(C)
iv only
32
When two like charges are brought together, the potential energy of the system formed will
پاسخ دهید
(A)
increase because work is done against the field
33
Two capacitors, each of capacitance 2\(\mu\)F are connected in parallel. If the p.d across them is 120V, calculate the charge on each capacitor
پاسخ دهید
(C)
2.4 x 10^-4C
34
Which of the following properties is an advantage of lead-acid accumulator over an alkaline accumulator?
پاسخ دهید
(D)
possesses high e.m.f
35
Six dry cells each of e.m.f. 2.0 and internal resistance of 1.0\(\Omega\) are connected in parallel across a load of 3.0\(\Omega\). Calculate the effective current in the circuit.
پاسخ دهید
(A)
0.63A
36

Two similar cells are used to light two similar lamps as illustrated in the diagrams above. In which of the circuit diagrams are the lamps brightest?
پاسخ دهید
(B)
Q
37
A 12\(\Omega\) resistor dissipates 8kJ of heat in 20s. Calculate the current through the resistor
پاسخ دهید
(A)
5.8A
38
The magnetic relay is a device used for
پاسخ دهید
(D)
controlling another circuit carrying larger current
39
the core of a transformer is usually laminated in order to
پاسخ دهید
(B)
reduce eddy current
40
Which of the following modes is the most economical method of transmitting electrical power over long distances?
پاسخ دهید
(C)
alternating current at high voltage and low current
41
An inductor is connected to a 24V, 50Hz mains supply. If the current through the inductor is 1.5A, calculate the inductance of the inductor (\(\pi = \frac{22}{7}\))
پاسخ دهید
(D)
5.1 x 10^-2H
42
In a R-C circuit
پاسخ دهید
(C)
V^rms lags I^rms by 90^o
43
An atom in an excited state is one whose
پاسخ دهید
(D)
electron have moved to higher energy level
44
A metal with a work function of 3.0ev is irradiated with ultraviolet light of energy 4.0 ev. The kinetic energy of the ejected electron is
پاسخ دهید
(A)
1.0eV
45
Which of the following statements about X-rays is correct? X-rays
پاسخ دهید
(B)
are produced when a metal target is used to block fast miving electrons