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WAEC Physics Past Questions 2020: West African Examinations Council (WAEC) is an examination board that conducts the West African Senior School Certificate Examination, In a year, over three million candidates registered for the exams coordinated by WAEC.

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WAEC Physics Past Questions 2020

WAEC Physics Past Questions 2020

WAEC Physics Questions Objective and Theory For Free 2020/2021

1. The inner diameter of a test tube can be measured accurately using a
A. micrometer screw gauge
B. pair of dividers
C. metre rule
D. pair of vernier calipers

2. Two bodies have masses in the ratio of 3:1. They experience forces that impart to them acceleration in the ratio 2:9 respectively. Find the ratio of forces the masses experienced.
A. 1 : 4
B. 2 : 1
C. 2 : 3
D. 2 : 5

3. Particles of mass 10-2kg are fixed to the tip of a fan blade which rotates with an angular velocity of 100rad-1. If the radius of the blade is 0.2m, the centripetal force is
A. 2 N
B. 20 N
C. 200 N
D. 400 N

4. A lead bullet of mass 0.05kg is fired with a velocity of 200ms-1 into a lead block of mass 0.95kg. Given that the lead block can move freely, the final kinetic energy after impact is
A. 50 J
B. 100 J
C. 150 J
D. 200 J

5. A ball of mass 0.1kg is thrown vertically upwards with a speed of 10ms-1 from the top of a tower 10m high. Neglecting air resistance, its total energy just before hitting the ground is
(take g = 10ms-2)
A. 5 J
B. 10 J
C. 15 J
D. 20 J

6. A car of mass 800kg attains a speed of 25m/s in 20 secs. The power developed in the engine is
A. 1 . 25 x 104 W
B. 2 . 50 x 104 W
C. 1 . 25 x 106W
D. 2 . 50 x 106 W

7. When the brakes in a car are applied, the frictional force on the tyres is

A. is a disadvantage because it is in the direction of the motion of the car
B. is a disadvantage because it is in the opposite direction of the motion of the car
C. is an advantage because it is in the direction of the motion of the car
D. is an advantage because it is in the opposite direction of the motion of the car

8. If the stress on a wire is 107NM-2 and the wire is stretched from its original length of 10.00 cm to 10.05 cm. The young’s modulus of the wire is
A. 5 . 0 x 104 Nm-2
B. 5 . 0 x 105 Nm-2
C. 2 . 0 x 108 Nm-2
D. 2 . 0 x 109 Nm-2

9. A solid weigh 10 .00 N in air, 6 N when fully immersed in water and 7 . 0 N when fully immersed in a liquid X. Calculate the relative density of the liquid, X.
A. 5/3
B. 4/3
C. 3/4
D. 7/10

10. When the temperature of liquid increases, its surface tension
A. Decreases
B. Increases
C. Remain Constant
D. Increases then decrease

11. A gas at a volume of V0 in a container at pressure P0 is compressed to one-fifth of its volume. What will be its pressure if the magnitude of its original temperature T is constant?
A. P0/5
B. 4P0/5
C. P0
D. 5P0

12. A piece of the substance of specific head capacity 450JKg-1K-1 falls through a vertical distance of 20m from rest. Calculate the rise in temperature of the substance on hitting the ground when all its energies are converted into heat. [g = 10ms-2]
A. 2/9°C
B. 4/9°C
C. 9/4°C
D. 9/2°C

Use this content below to answer only No. 13

I. A liquid boils when its saturated vapour pressure is equal to the external pressure
II. Dissolved substances in pure water lead to an increase in the boiling point.
III. When the external pressure is increased, the boiling point increases.
IV. Dissolved substances in pure water decrease the boiling point.

13. Which combination of the above are peculiarities of the boiling point of a liquid?
A. I, II and III
B. I, II, III and IV
C. I, II and IV
D. II, III and IV

14. The temperature gradient across a copper rod of thickness 0.02m, maintained at two temperature junctions of 20°C and 80°C respectively is
A. 3.0 x 102Km-1
B. 3.0 x 103Km-1
C. 5.0 x 103Km-1
D. 3.0 x 104Km-1

15. Calculate the mass of ice that would melt when 2kg of copper is quickly transferred from boiling water to a block of ice without heat loss;
Specific heat capacity of copper = 400JKg-1K-1
Latent heat of fusion of ice = 3.3 x 105JKg-1
A. 8/33kg
B. 33/80kg
C. 80/33kg
D. 33/8kg

16. The equation of a wave traveling along the positive x-direction is given by;
y = 0.25 x 10-3 sin (500t – 0.025x).
Determine the angular frequency of the wave motion.
A. 0.25 x 10-3rad s-1
B. 0.25 x 10-1rad s-1
C. 5.00 x 102rad s-1
D. 2.50 x 103rad s-1

17. If a sound wave goes from a cold air region to a hot air region, its wavelength will
A. increase
B. decrease
C. decrease then increase
D. remain constant

18. The lowest note emitted by a stretched string has a frequency of 40Hz. How many overtones are there between 40hz and 180Hz?
A. 4
B. 3
C. 2
D. 1

19. A man stands 4m in front of a plane mirror. If the mirror is moved 1m towards the man, the distance between him and his new image is
A. 3m
B. 5m
C. 6m
D. 10m

20. The inside portion of part of a hollow metal sphere of diameter 20cm is polished. The portion will therefore form
A. concave mirror of focal length 5cm
B. concave mirror of focal length 10cm
C. convex mirror of focal length 5cm
D. convex mirror of focal length 20cm

21. The velocities of light in air and glass are 3.0 x 108ms-1 and 2.0 x 108ms-1 respectively. If the angle of refraction is 30°, the sine of the angle of incidence is
A. 0.33
B. 0.50
C. 0.67
D. 0.75

22. An astronomical telescope is said to be in normal adjustment when the
A. eye is accommodated
B. focal length of the objective lens is longer than that of eyepiece
C. final image is at the near point of the eye
D. final image is at infinity

23. Which of the following electromagnetic waves is least energetic?
A. Infra-red rays
B. X-rays
C. Ultra-violet rays
D. Gamma rays

24. Steel is more suitable for permanent magnet than iron because the former
A. is easily demagnetized by sharing vigorously
B. is an alloy of many metals
C. is easily magnetized by alternating current through one cycle
D. retains magnetism more than iron

25. Four cells each of e.m.f 1.5V and internal resistance of 4Ω are connected in parallel. What is the effective e.m.f. and internal resistance of the combination?
A. 6.0V, 16Ω
B. 6.0V, 1Ω
C. 1.5V, 4Ω
D. 1.5V, 1Ω

26. A 3000W electric cooker is to be used on a 200V mains circuit. Which of the fuses below can be used safely with the cooker?
A. 2A
B. 5A
C. 10A
D. 20A

27. A galvanometer has a resistance of 5Ω. By using a shunt wire of resistance 0.05Ω, the galvanometer could be converted to an ammeter capable of reading 2Amp. What is the current through the galvanometer?
A. 2mA
B. 10mA
C. 20mA
D. 25mA

28. In fleming’s right-hand rule, the thumb, the forefinger and the middle finger if held mutually at right angles represent respectively, the
A. motion, the field and the induced current
B. induced current, the motion and the field
C. field, the induced current and the motion
D. induced current, the field and the motion

29. At what frequency would a 10H inductor have a reactance of 2000Ω?
A. π/200Hz
B. π/100Hz
C. 100/πHz
D. 100πHz

30. The core of an efficient transformer should consist of laminated pieces of metal in order to
A. increase the heat produced by increasing the eddy current
B. increase the heat produced by reducing the eddy current
C. reduce the heat produced by increasing the eddy current
D. reduce the heat produced by reducing the eddy current

31. Gamma rays are produced when

A. high-velocity electrons are abruptly stopped in metals
B. energy changes occur within the nucleus of atoms
C. energy changes occur within the electronic structure of atoms
D. electrons are deflected in very strong magnetic fields

32. What is the speed of a particle of mass 10-27kg whose wavelength is 10-8m.
[h = 6.63 x 10-34Js]
A. 6.63ms-1
B. 66.30ms-1
C. 663.00ms-1
D. 6630.00ms-1

33. In a series R-L-C circuit at resonance, the voltages across the resistor and the inductors are 30V and 40V respectively, what is the voltage across the capacitor?
A. 30V
B. 40V
C. 50V
D. 70V

34. In the Rutherford scattering experiment, a beam of alpha particles was fired at a thin gold film with some of the particles being considerably deflected. This shows that
A. a gold nucleus contains protons, neutrons, and electrons uniformly distributed in a tiny volume
B. the gold nucleus is positively charged and is concentrated in a tiny volume
C. the gold nucleus emitted alpha particles
D. the gold nucleus is concentrated in a tiny volume and contains alpha particles

35. 2311Na + Proton → pqX + alpha particle
What are the values of p and q respectively in the equation above?
A. 10 and 20
B. 12 and 24
C. 20 and 10
D. 24 and 12

36. A semiconductor diode is used in rectifying alternating current into direct current mainly because of it.
A. allows current to flow in either direction
B. is non-linear
C. offers a high input resistance
D. allows current to flow only in one direction

37. If ∆x is the uncertainty in the measurement of the position of a particle along the x-axis and ∆Px is the uncertainty in the measurement of the linear momentum along the x-axis, then the uncertainty principle relation is given as
A. ∆x ∆Px ≥ h
B. ∆x ∆Px = 0
C. ∆x ∆Px < h
D. ∆x ∆Px = ∞

38. When a ship sails from saltwater into freshwater, the fraction of its volume above the water surface will

A. increase
B. decrease
C. remain the same
D. increase then decrease

Use this content below to answer only No. 39

I. Its velocity is constant
II. No work is done on the body
III. It has constant acceleration directed away from the centre
IV. The centripetal force is directed towards the centre

39. Which combination of the above is true of a body moving with constant speed in a circular track?
A. II and IV
B. I and IV
C. II and III
D. I and III

40. The velocity ratio of a machine is 5 and its efficiency is 75%. What effort would be needed to lift a load of 150N with the machine?
A. 20N
B. 30N
C. 40N
D. 50N

41. At a fixed point below a liquid surface, the pressure downwards is P1 and pressure upwards is P2. It can be deduced that
A. P1 > P2
B. P1 ≥ P2
C. P1 < P2
D. P1 = P2

42. If the force and the velocity on a system are each reduced simultaneously by half, the power of the system is
A. doubled
B. reduced to a quarter
C. reduced by half
D. constant

43. A catapult used to hold a stone of mass 500g is extended by 20cm with an applied force F. If the stone leaves with a velocity of 40m/s, the value of F is
A. 4.0 x 102N
B. 2.0 x 103N
C. 4.0 x 103N
D. 4.0 x 104N

44. A stream is flowing at 0.75ms-1 and a boat heading perpendicular for the stream landed at the opposite bank at an angle of 30°. Calculate the velocity of the boat.
A. 1.50ms-1
B. 1.00ms-1
C. 0.86ms-1
D. 0.65ms-1

45. A rope is being used to pull a mass of 10kg vertically upward. Determine the tension in the rope if, starting from rest, the mass acquires a velocity of 4ms-1 in 8s [g = 10ms-2]
A. 5N
B. 50N
C. 95N
D. 105N

Use this content below to answer only No. 46

I. The frictional force is independent of the area of the surfaces in conduct
II. The frictional force depends on the nature of the surfaces in contact
III. The frictional force depends on the speed of sliding
IV. The frictional force is directly proportional to the normal reaction.

46. Which combination of the above is true of sliding friction?
A. I, III and IV
B. I, II and IV
C. I, II and III
D. II, III and IV

47. Total internal reflection occurs when light moves from
A. a dense medium to a less dense medium
B. air to water
C. water to glass
D. a less dense to a dense medium

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