## Physics 2020 Past Question | WAEC

Study the following past questions and answers for JAMBWAEC  NECO and Post-JAMB. Get prepared with official past questions and answers for upcoming examinations.

31. Which of the following statements about the motion of a simple pendulum is true?

• A. It is a simple harmonic motion when the angle of displacement is large
• B. It passes the equilibrium position with minimum speed
• C. It possesses maximum kinetic energy at the extreme positions
• D. lt swings faster at the poles than at the equator

32. An electron of mass m and charge e moves in a circular path in a magnetic field of flux density B. How long does it take to complete one orbit?

• A. 2me/Bπ
• B. 2Bmeπ2B/meπ
• C. 2πm/Be
• D. Be/2πm

33. Which of the following statements about photoelectrons is correct?

• A. A faint green light produces photoelectrons with less kinetic energy than a bright red light
• B. A red light releases a smaller number of electrons than a green light
• C. A faint green light produces photoelectrons with greater kinetic energy than a bright red light
• D. A red light produces more photoelectrons than a green light

34. The sketched graph above illustrates the heating curve of a 0.02kg of water. Determine the approximate value of the specific latent heat of vapourization of water

• A. 2.25 x 106 J kg−1
• B. 4.17 x 103 J kg−1
• C. 2.00 x 103 J kg−1
• D. 1.00 x 103 J kg−1

35. In the hydraulic press, the force F applied is related to the diameter d of the cylinder by

• A. F α d2
• B. F α d
• C. F α d−1
• D. F α d−2

36. In an electric circuit, an inductor of inductance 0.5 H and resistance 50Ωis connected to an alternating current source of frequency 60 Hz. Calculate the impedance of the circuit.

• A. 50.0Ω
• B. 450.5 Ω
• C. 195.0 Ω
• D. 1950.1 Ω

37. Which of the following statements correctly explains why a total solar eclipse would be seen by people on only a small portion of the earth’s surface? The

• A. moon is larger in diameter than the earth
• B. earth is larger in diameter than the sun
• C. earth revolves around the sun
• D. earth is larger in diameter than the moon.

38. Water waves have a wavelength of 3.6cm and speed of 18cms−1in deep water. If the waves enter shallow water with wavelength of 2.0cm, calculate the speed of the waves in the shallow water.

• A. 0.4cms−1
• B. 2.5cms−1
• C. 10.0cms−1
• D. 10.8cms−1

39. An a.c. generator can be converted to a d.c. electric motor by replacing the

• A. slip rings with a split ring and connecting a battery
• B. split ring with slip rings and connecting a battery
• C. a.c. with d.c. source and connecting slip rings
• D. a.c. with d.c. source and connecting split rings

40. A ray of light travels obliquely from a less dense medium to a denser medium. Which of the following statements is true about the light?

• A. The wavelength of the light increases in the second medium
• B. The speed of the light increases in the second medium
• C. The light refracts towards the normal
• D. There Is a change in the frequency of the light

41. An electron of mass 9.1x 1031kg is travelling at a speed of 2.0 x 1066ms−1. Calculate the associate wavelength of the electron. [h = 6.6. x 1034Js]

• A. 3.63 x1010 m
• B. 3.63 x 10−8 m
• C. 3.63 x 10−7 m
• D. 6.89 x 10−4 m

42. Which of the following statements about the process of melting of a solid are true? The temperature of the solid will

1. remain steady until melting starts.
2. keep rising until melting starts,

Ill remain steady as melting proceeds.

V, keep rising as melting proceeds.

• A. II and llI only
• B. IlI and IV only
• C. I, Il and Ill only
• D. ll and IV only

43. A diver steps off a diving platform that is 10m above the water. If there is no air resistance during the fall, there will be a decrease in the diver’s

• A. gravitational potential energy
• B. total mechanical energy
• C. kinetic energy
• D. momentum

44. Which of the following actions would increase the electric force between two positively charged particles?

• A. Decreasing the mass of the particles
• B. Decreasing the distance between the particles
• C. Increasing the assistance between the particles D. Increasing the mass of the particles

45. A luminous object is one that

• A. gives off dim blue-green light only in the dark.
• B. gives out light of its own
• C. shines by reflected light only
• D. glows only in the presence of light

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