## Physics 2020 Past Questions | JAMB

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

16. A solid weighs 4.8g in air, 2.8g in water and 3.2g in Kerosine. The ratio of density of the solid to that of the kerosine is

• A. 2
• B. 3/2
• C. 2/3
• D. 3

17. One of the following readings represents the measurement of the length of a metal rod using vernier callipers. Taking the reading accuracy into consideration, the most likely one is

• A. 5.16cm
• B. 5.165cm
• C. 5.0cm
• D. 5.160cm

18. When a sound wave passes from air into water its

• A. speed and frequency increases but its wavelength remains the same
• B. speed and wavelength increases but its frequency remains the same
• C. speed decreases
• D. speed increases but its frequency and wavelength decreases

19. A convex mirror is used as a driving mirror because

I. its image is erect

II. It has a large field of view

III. It has a long focal length

Identify the CORRECT statement(s)

• A. I and III only
• B. I and II only
• C. II and IIII only
• D. I, II and III only

20. Two mirrors of the same length are arranges as show in the diagram. A ray of light NO strikes the system at O and emerges along PQ. The emergent ray has been deviated through

• A. 220o
• B. 200o
• C. 210o
• D. 180o

21. A magnetic needle is suspended first at the earth’s north magnetic pole and then at a point on the magnetic equator. The respective angles between the needle and the horizontal are

• A. 0o and 0o
• B. 60o and 60o
• C. 90o and 90o
• D. 90o and 0o

22. A hydrometer is an instrument for measuring the

• A. a depth of water of water in a vessel
• B. relative density of a liquid by the method of flotation
• C. relative density of a liquid by finding the apparent loss in weight
• D. relative humidity of the air

23. Consider the three forces acting at O and in equilibrium as shown in the figure. Which of the following equations is/are CORRECT?

1. P1cos θ1 = p1 cos θ2
2. P3= P1cos θ4  + P2cos2

III. P1sinθ1=P2sinθ2

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

24. The refractive index of a liquid is 1.5. If the velocity of light in vacuum is 3.0 x 108ms−1, the velocity of light in the liquid is

• A. 1.5 x 108ms−1
• B. 2.0 x 108ms−1
• C. 3.0 x 108ms−1
• D. 4.5 x 108ms−1

25. A ship travelling towards a cliff receives the echo of its whistle after 3.5 seconds. A short while later, it receives the echo after 2.5 seconds. If the speed of sound in air under the prevailing condition is 250ms -1, how much closer is the ship to the cliff?

• A. 10m
• B. 350m
• C. 175m
• D. 125m

26. Which of the following statements about defects of vision is/are CORRECT?

1. For a long sighted person, close objects appear blurred
2. For a short sighted person, distant objects appear blurred

III. Short sight is corrected by using a pair of converging lenses

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

27. Which of the following conditions are necessary and sufficient for total internal reflection to take place at the boundary between two optical media?

1. Light is passing from optical denser medium to optically less dense medium
2. Light is passing from optically less dense medium to optically denser medium

III. Angle of incidence is greater than a certain critical value

1. Angle of incidence is lesser  than a certain critical value

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

28. The linear expansivity of brass is 2 x 10−5oC−1. If the volume of piece of brass is 10cm3at 0o What will be its volume at 100oC?

• A. 10.06cm3
• B. 10.04 cm3
• C. 10.02 cm3
• D. 10.20 cm3

29.  The lower and upper fixed points marked on a Mercury-in-glass thermometer are 210mm apart. The end of the mercury column in the tube is 49mm above the lower fixed point in a room. What is the temperature of the room in degrees Celsius?

• A. 55.3oC
• B. 23.3oC
• C. 49.0oC
• D. 16.43oC

30. Heat is supplied uniformly at the rate of 100W to 1.0 x 10−2kg of a liquid for 20 seconds. If the temperature of the liquid rises by 5oC, then the specific heat capacity of the liquid is

• A. 2.0 x 1022Jkg−1K−1
• B. 2.0 x 1022Jkg−1
• C. 4.0 x 1044Jkg−1−1K−1
• D. 4.0 x 1044Jkg−1
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