WAEC Physics 1992 Past Questions

Practice each question, then open it to see the full details.

Which of the following is a scalar quantity?

A.Momentum
B.Acceleration
C.Displacement
D.Distance
E.Force

(a) Explain what is meant by the following statement. The specific latent heat of fusion of ice is \(3.4 \times 10^{5}Jkg^{-1}\).

(b) Describe an experiment to determine the specific latent heat of fusion of ice. State two precautions necessary to obtain an accurate result.

Theory

Question 2

The diagram above represents the trajectory of a projectile with an initial velocity U. Calculate the time taken to reach the maximum height. (Take g as acceleration due to gravity)

A.Usinθ/2g
B.2Usinθ/g
C.Ucosθ/g
D.2Ucosθ/g
E.Usinθ/g

Objective

Question 2

(a)(i) What is meant by resonance?

(ii) Outline the necessary steps taken in a simple experiment to illustrate top resonance

(iii) Explain why a vibrating tuning fork sounds louder when its stem is pressed against a table top than when held in air.

(b) Explain with the aid of diagrams, how a concave mirror could be used to: (i) Ignite a piece of carbon paper; (ii) produce an exact copy of a picture on a screen.

Theory

Question 3

What change in velocity would be produced on a body of mass 4kg if a constant force of 16 N acts on it for2 s?

A.0.5 ms^-1
B.2.0ms^-1
C.8.0 ms^-1
D.32.0 ms^-1
E.128.0 ms^-1

Objective

Question 3

(a) Draw a simple labelled diagram illustrating the principle of a step-down transformer and explain how it works

(b) State three ways by which energy is lost in a transformer and how they can be minimized.

(c) If a transformer is used to light a lamp rated at 60W, 220V from a 4400V a.c. supply, calculate the; (i) ratio of the number of turns of the primary coil to the secondary coil in the transformer (ii) current taken from the main circuit if the efficiency of the transforme is 95%.

Theory

Question 4

Which of the following statements about solid friction is/are correct? I. Friction depends on the nature of the surfaces in contact II. Friction depends on the area of contact III. Friction always acts in the direction of motion.

A.I only
B.II only
C.III only
D.I and II only
E.I,II and III

Objective

Question 4

(a) Explain what is meant by photoelectric emission

(b) Draw a labelled diagram showing the structure of a simple type of a photocell and explain its mode of operation.

(d) In a photocell, no electrons are emitted until the threshold frequency of light is reached. Explain what happens to the energy of the light before emission of electrons begins. State one factor that may affect the number of emitted electrons.

Theory

Question 5

A body accelerates uniformly from rest at the rate of 3 ms^-1 for 8 seconds. Calculate the distance covered by the body during the acceleration.

A.12m
B.24m
C.48m
D.72m
E.96m

Objective

Question 6

Which of the following has the same unit as the moment of a force?

A.Force
B.Power
C.Work
D.Momentum
E.Impulse

Objective

Question 7

Solid weighs 0.040 N in air and 0.024 N when fully immersed in a liquid of density 800 kg m^-3. What is the volume of the solid? (g = 1Oms²)

A.2.0 x 10^-6m³
B.2.5x10^-6m³
C.3.0x10^-6m³
D.2.0x 10^-5m³
E.3.0 x 10^-5m³

Objective

Question 8

Which of the following will reduce the frequency of oscillation of a simple pendulum?

A.Increasing the mass of the bob
B.Decreasing the mass of the bob
C.Increasing the length of the string
D.Decreasing the length of the string
E.Increasing the amplitude of oscillation

Objective

Question 9

A force of 20 N applied parallel to the surface of a horizontal table, is just sufficient to make a block of mass 4kg move on the table. Calculate the coefficient of friction between the block and the table. (g = 10ms²)

A.0.05
B.0.20
C.0.50
D.0.80
E.2.00

Objective

Question 10

A barometer can be used in determining the I. height of a mountain II. depth of a mine III. dew point. Which of the following is/are correct?

A.I, II and III
B.II and III only
C.I and III only
D.I and II only
E.III only

Objective

Question 11

A body of mass 5kg falls from a height of 10m above the ground. What is the kinetic energy of the body just before it strikes the ground? (Neglect energy losses and take gas 10ms²)

A.5J
B.25J
C.250J
D.500J
E.625J

Objective

Question 12

Steel bars, each of length 3.0 m at 28°C, are to be used for constructing a rail line. If the linear expansivity of steel is 1.0 x 10^-5°C, what is the safety gap that must be left between successive bars if the highest temperature expected is 40^oC?

A.1.2 x 10^-1cm
B.8.4 x 10^-2cm
C.7.2 x10^-2cm
D.3.6 x 10^-2cm
E.1.8 x 10^-2cm

Objective

Question 13

Which of the following statements is/are correct? I. Pure water freezes at 0^oC under normal pressure ll. Water has its highest density at 4^oC. III. The volume at 4^oC,

A.I only
B.II only
C.I and II only
D.I and III only
E.II and III only

Objective

Question 14

A given mass of gas at a temperature of 30°C is trapped in a tube of volume V. Calculate the temperature of the gas when the volume is reduced to two-third of its original value by applying a pressure twice the original value.

A.71^oC
B.40^oC
C.131^oC
D.313^oC
E.404^oC

Objective

Question 15

Which of the following colours of surfaces will radiate heat energy best?

A.Red
B.White
C.Black
D.Yellow
E.Blue

Objective

Question 16

A gas which obeys Charles’ law exactly has a volume of 283cm³ at 10^oC. What is its volume at 30^oC?

A.142cm³
B.293cm³
C.303cm³
D.566cm³
E.849cm³

Objective

Question 17

Which of the following best explains why a person suffers a more severe burn when his skin is exposed to steam than when boiling water pours on his skin?

A.Steam is at a higher temperature than boiling water
B.Steam possesses greater heat energy per unit mass than boiling water
C.Steam spreads more easily over a wider area of the skin man boiling water
D.Steam penetrates more deeply into the skin than boiling water
E.the specific latent heat of vaporization is released in changing from boiling water to steam

Objective

Question 18

A small circular membrane is 10cm below the surface of a pool of mercury when the barometric height is 76 cm of mercury. If the density of mercury is 13600\(kgm^{-3}\), what is the pressure on the membrane in \(Nm^{-2}\)? \((g =10ms^{-2})\)

A.1.17 x 10⁷ Nm^-2
B.6.80 x 10⁵Nm^-2
C.1.17x10⁵Nm^-2
D.1.03 x 10⁵Nm^-2
E.1.36 x10⁴ Nm^-2

Objective

Question 19

Which of the following instruments is used to measure relative humidity?

A.Hydrometer
B.Barometer
C.Manometer
D.Hypsometer
E.Hygrometer

Objective

Question 20

A metal of mass 1.5 kg was heated from 27^oC to 47^oC in 4 minutes by a boiling ring of 75 W rating. Calculate the specific heat capacity of the metal, (Neglect heat losses to the surrounding)

A.2.5 X10³J kg^-10C^-1
B.6.0 X10²J kg^-10C^-1
C.2.5 x 10²J kg^-10C^-1
D.1.4 X10²J kg^-10C^-1
E.1.0 x 10²J kg^-10C^-1

Objective

Question 21

A ray of light strikes a plane mirror at an angle of incidence i. Determine in terms of i the angle of deviation of the ray after reflection from the mirror.

A.i
B.2i
C.90^o-i
D.90^o+ i
E.180^o - 2i

Objective

Question 22

Images formed by a convex mirror are always

A.inverted, real and diminished
B.inverted, virtual and diminished
C.erect, virtual and diminished
D.erect, real and magnified
E.erect, virtual and magnified

Objective

Question 23

Which of the following statements is not correct for a light ray passing through a rectangular glass block which is surrounded by air? It

A.suffers a displacement at the point of emergence
B.emerges parallel to the incident ray
C.is partly reflected at the point of incidence
D.is deviated at the point of emergence
E.is reflected in the block

Objective

Question 24

In an experiment to measure1 the focal length f of a converging lens object distances u and corresponding image distance were measured and 1/u plotted against 1/v to obtain the graph illustrated. How would f be determined from this graph?

A.f= the slope of the graph
B.f= the intercept on the 1/u axis
C.f =the intercept on the 1/v axis
D.f = reciprocal of the slope
E.f = reciprocal of the intercept on either axes

Objective

Question 25

The image of a pin formed by a diverging lens of focal length 10cm is 5cm from the lens. Calculate the distance of the pin from the lens

A.-3.3cm
B.3.3cm
C.10.0cm
D.15.0cm
E.20.0cm

Objective

Question 26

As an object is moved close to the focus of a converging lens from infinity its image I. moves closer to the lens II. moves away from the lens. III. Remains the same size. IV becomes smaller. Which of the statements above is/are correct?

A.III and IV only
B.I and III only
C.IV only
D.III only
E.II only

Objective

Question 27

A real image of an object fom1ed by a converging lens of focal length 15cm is three times the size of the object. What is the distance of the object from the lens?

A.30cm
B.25cm
C.20cm
D.15cm
E.10cm

Objective

Question 28

The eye defect illustrated in the diagram above can be corrected by a

A.convex mirror
B.concave mirror
C.diverging lens
D.converging lens
E.piano-converging lens

Objective

Question 29

When an astronomical telescope is in normal adjustment, the focal length of the objective lens is 50cm and that of the eyepiece is 2.5om. What is the distance between the lenses?

A.20.0cm
B.47.5cm
C.50.0cm
D.52.5cm
E.125.0cm.

Objective

Question 30

Which of the following is used for controlling the amount of light entering the eye?

A.Cornea
B.Pupil
C.Iris
D.Optic nerve
E.Ciliary muscle

Objective

Question 31

The angle of deviation of light of various colours passing through a glass prism decreases in the order of

A.blue orange and red
B.red, blue and orange
C.blue, red and orange
D.red, orange and blue
E.orange, blue and red

Objective

Question 32

The change of the direction of a wavefront as a result of a change in the velocity of the wave in another medium is called

A.refraction
B.reflection
C.diffraction
D.polarization

Objective

Question 33

The diagram above shows a waveform in which energy is transferred from A to B in a time of 2.5 x 10-3s. Calculate the frequency of the wave

A.2.0 x 10³Hz
B.1.0 x 10³Hz
C.4.0 x 10^-2Hz
D.1.0 x 10^-3Hz
E.5.0 x 10⁴Hz.

Objective

Question 34

Which of the following radiations have the highest frequency?

A.Radio waves
B.Light waves
C.X-rays
D.infra-red rays
E.Ultraviolet rays

Objective

Question 35

How far from a cliff should a boy stand in order to hear the echo of his clap 0.9s later? (Speed of sound in air = 330 ms^-1)

A.36.67m
B.74.25m
C.148.50m
D.297.00
E.366.67m

Objective

Question 36

Which of the following waves are longitudinal waves? l. Ripples on the surface of water II. Waves produced by a tuning fork vibrating in air III. Light waves
IV. Waves produced by a flute

A.I and II only
B.I and III only
C.II and III only
D.II and IV only
E.III and IV only

Objective

Question 37

Which of the following statements is not true?

A.Musical notes consist of the combination of sounds of regular frequency
B.The combination of overtones produced by an instrument determines the quality of the sound
C.the loudness of sound is determined by its frequency
D.the pitch of a note depends on the frequency of vibration of the source
E.Noise can be produced by a combination of sounds of irregular frequency

Objective

Question 38

A pipe closed at one end is 1.0m long. The air in the pipe is set into vibration and a fundamental note of frequency 85Hz is produced. Calculate the velocity of sound in the air. (Neglect end correction).

A.340.0ms^-1
B.33Oms^-1
C.170ms^-1
D.85.0ms^-1
E.42.5ms^-1

Objective

Question 39

The diagram above shows the magnetic field around a bar magnet which has its N-pole pointing north. The neutral points in the field are likely to occur at

A.1 and 2
B.3 and 4
C.5 and 6
D.7 and 8
E.9 and 10

Objective

Question 40

A negatively charged rod is brought near the cap of a gold-leaf electroscope. The cap is earthed momentarily while the rod is near to it. The rod is then removed. Which of the following is correct?

A.The cap will be positively charged and the negatively charged leaves will diverge
B.The cap will be negatively charged and the positively charged leaves will diverge
C.The cap and the leaves will be positively charged
D.The cap and the leaves will be negatively charged.
E.The leaves will not diverge because the cap has been earthed.

Objective

Question 41

Calculate the rate at which energy is used up in the circuit illustrated by the diagram

A.0 W
B.2 W
C.4 W
D.8 W
E.16 W

Objective

Question 42

Which of the following is not a consequence of hydrogen bubbles covering the copper plate of a primary cell?

A.Polarization
B.Local action
C.Formation of hydrogen electrode
D.Increase in the resistance of the cell
E.Generation of less current by the cell

Objective

Question 43

Calculate the length of a constantan wire of cross- sectional area 4 π x 10^-8m² and resistivity 1.1 x 10^-6 Ω m required to construct a standard resistor of resistance 21 Ω. [Take π = 22/7]

A.0.42m
B.2.40 m
C.6.25 m
D.183.75 m
E.590.00 m

Objective

Question 44

In a domestic circuit, electrical appliances and lamps are arranged in parallel across the mains so as to enable the

A.same current to flow through the electrical appliances and the lamps
B.maximum energy to be consumed at least cost
C.same fuse to be used for the electrical appliances and the lamps
D.voltage across the appliances not to be affected when the lamps are switched on and off
E.heat losses to be minimized

Objective

Question 45

Calculate the time in which 4.8 kJ of energy would be expended when an electric heater of resistance 1.8 x 10³Ω is used on a 240 V mains supply. (Neglect heat losses to the surrounding).

A.150.0s
B.90.0s
C.36.0s
D.20.0s
E.2.7s.

Objective

Question 46

Lenz’s law of electromagnetic induction states that

A.electromotive force is induced in a circuit whenever there is a change in the magnetic flux linked with the circuit
B.the induced current in a conductor is in such a direction as to oppose the change producing it
C.the induced e.m.f. in a circuit is proportional to the rate of change of number of lines of force linking the circuit
D.a force is exerted on a current carrying conductor in a magnetic field
E.the induced e.m.f. is proportional to the current producing the magnetic flux.

Objective