16. A small amount of air is introduced into the vacuum above the mercury in a mercury barometer tube. The mercury level goes down because the air molecules
- A. heat the mercury and make it expand
- B. increase the pressure above the mercury.
- C. cool the mercury and make it contract.
- D. decrease the pressure above the mercury
17. Calculate the quantity of heat needed to change the temperature of 60g of ice at 0 °C to 80 °C. [specific latent heat of fusion of ice= 3.36 x 105Jkg−1specific heat capacity of water 4.2 x 103 J kg−1]
- A. 4.80 kJ
- B. 20.16 kJ
- C. 40.32 kJ
- D. 22.17 kJ
18. The wire of a platinum resistance thermometer has d resistance of 3.5Ωat 0 °C and 10.52Ωat 100°C. Calculate the temperature of the wire when its resistance is 7.5Ω.
- A. 78 °C
- B. 25 oC
- C. 30oC
- D. 57 oC
19. A transverse pulse of frequency 9 Hz traves 4.5m in 0.6 s. Calculate the wavelength of the pulse.
- A. 3.33 m
- B. 0.30 m
- C. 0.83 m
- D. 1.20 m
20. In which of the following media is the speed of sound the least?
- A. Air
- B. Brass
- C. Water
- D. Wood
21. Which of the following characteristics of waves can a ripple tank be used to demonstrate?
- A. I, II and Ill
- B. ll and ll only
- C. l and lII only
- D. I and II only
22. Which of the following graphs gives the correct relationship between energy and mass when mass is converted to energy?
- A. A
- B. B
- C. C
- D. D
23. An 800 kg car moving at 80 km hr−1 collides with a 1200 kg car moving at 40 km hr−1in the same direction. If the cars stick together, calculate their common velocity.
- A. 60 km hr−1
- B. 8 km hr−1
- C. 40 km hr−1
- D. 56 km hr−1
24. The mass of a load is doubled while the force acting on it is halved. The resulting acceleration of the load is
- A. quadrupled
- B. quartered
- C. halved
- D. doubled
25. The maximum and minimum thermometer reads the
- A. the maximum temperature during the day and the minimum temperature at night at all times.
- B. the maximum temperature at night and minimum temperature during the day from the last reset
- B. the maximum temperature at night and minimum temperature during the day at all times
- D. the maximum temperature during the day and minimum temperature at night from the last reset
26. An a.c. the generator can be converted to a d.c. generator by replacing the
- A. commutator with an armature
- B. armature with a commutator
- C. commutator with slip rings
- D. slip rings with a commutator
27. Which of the following statements is the correct reason for using soft iron in making the armature or an electric bell?
- A. It is a diamagnetic material
- B. It loses its magnetism readily
- C. It is not easily magnetized
- D. It retains its magnetism for a long time
28. The diagram above illustrates a meter bridge circuit under balanced condition. Determine the value of x.
- A. 71.4 cm
- B. 10.0 cm
- C. 28.6 cm
- D. 57.2 cm
29. Which of the following devices is used for storing electric charges?
- A. Transformer
- B. Ammeter
- C. Potentiometer
- D. Capacitor
30. An electron of mass 9.1 x 10−31kg moves with a speed of 2.0 x 106ms−1round the nucleus of an atom in a Circular path of radius 6.1 x 1011 Determine the angular speed of the electron.
- A. 3.28 x 1016 rad s−1
- B. 8.55 x 103 rad s−1
- C. 9.11 x 1013 rad s−1
- D. 5.22 x 1015 rad s−1