11. A block and tackle pulley arrangement has 6 pulleys in which an effort of 50N supports a load of 200N, calculate the efficiency of the machine
- A. 80.0%
- B. 76.6%
- C. 66.7%
- D. 60.7%
12. Three 3ω resistance are connected in parallel what is the equivalent resistance?
- A. 1ω
- B. 9ω
- C. 3ω
- D. 0.33ω
13. Which of the following instruments helps to maintain the correct humidity and temperature of a building?
- A. A compressor
- B. A refrigerator
- C. Air blower
- D. Air conditioner
14. The thermal expansion of a solid is an advantage in
- A. Balance wheel of a watch
- B. Construction of steel rail lines
- C. Construction of large steel bridges
- D. Fitting of tyres on wheels
15. The S.I unit of moment of a force is
- A. kgm
- B. µm
- C. Jm
- D. µm−1
16. A block and tackle pulley arrangement has 6 pulleys in which an effort of 50N supports a load of 200N, calculate the efficiency of the machine
- A. 80.0%
- B. 76.6%
- C. 66.7%
- D. 60.7%
17. Calculate the light of the image formed by a pinhole camera of length 12cm used to photograph an object 60cm away from the hole and 70cm high
- A. 10 cm
- B. 16 cm
- C. 5 cm
- D. 14 cm
18. When two objects P and Q are supplied with the same quantity of heat, the temperature change in P is observed to be twice that of Q. The mass of P is half that of Q. The ratio of the specific heat capacity pf P to Q is
- A. 1:4
- B. 4:1
- C. 1:1
- D. 2:1
19. When the r.m.s value of a source of electricity supply is given as 240v, it means that the peak value of the supply is
- A. 240v
- B. 340v
- C. 480v
- D. 57600v
20. Which of the following operations can be used to convert an alternative current dynamo into a direct current dynamo
- A. number of turns in the coil is increased
- B. strength of the field magnet is increased
- C. slip rings are replaced with split ring cummutator
- D. coil is wound on a soft iron armature
