A/L 2001 Physics MCQ - Questions 21 - 30

21. The equivalent resistance between X and Y in the network of resistances shown is

1. (1) r
2. (2) R
3. (3) 2R
4. (4) 2R + r
5. (5) 4R + r
6. Answer with explanation
22. An
    
    object of mass m is hung by a string and is kept in equilibrium as shown in the diagram by a horizontal force F. The magnitude of F is
1. (1) mg tanθ
2. (2) mg sinθ
3. (3) mg
4. (4) mg cosθ
5. (5)
6. Answer with explanation
23. 
    Two equal masses A and B are attached to a light inextensible string passing over a smooth light pulley as shown in the diagram. The mass B is moved down, held it stationary and then released it. Which of the following statement is correct for the subsequent motion of B?
1. (1) B will move to the original position
2. (2) B will start to oscillate up and down and come to rest
3. (3) B will stay stationary
4. (4) B will start to move downwards
5. (5) B will start to move upwards
6. Answer with explanation
24. Two masses joined by alight string are pulled along a smooth horizontal table as shown in the diagram.
    
    
    
    What is the tension in the string joining the masses?
1. (1) 4 N
2. (2) 8 N
3. (3) 12 N
4. (4) 20 N
5. (5) 30 N
6. Answer with explanation
25. 
    A current I flows around a closed loop as shown in the figure. The magnetic flux density produced at the center O is given by
1. (1)
2. (2)
3. (3)
4. (4)
5. (5)
6. Answer with explanation
26. A compass is placed on top of a wire as shown in the diagram.
    
    
    When a large current is passed through the wire, which one of the following diagrams best represents the direction of the compass needle? Neglect the effects due to the earth's magnetic field.
1. (1)
2. (2)
3. (3)
4. (4)
5. (5)
6. Answer with explanation
27. Radioactive  nucleus emits two β^- emissions followed by an α emission. The resulting nucleus will have,
1. (1) 86 protons and 140 neutrons
2. (2) 88 protons and 140 neutrons
3. (3) 90 protons and 140 neutrons
4. (4) 90 protons and 142 neutrons
5. (5) 96 protons and 142 neutrons
6. Answer with explanation
28. A fossil is found to be 72,000 years old by carbon -14 dating. If the half life of C is 6,000 years, the ratio
    
     is,
1. (1)
2. (2)
3. (3)
4. (4)
5. (5)
6. Answer with explanation
29. An astronomical telescope has an eyepiece of focal length 5 cm. At normal adjustment the separation between the eyepiece and the objective is 85 cm. The angular magnification of the telescope at normal adjustment is
1. (1) 90
2. (2) 85
3. (3) 80
4. (4) 17
5. (5) 16
6. Answer with explanation
30. A uniform elastic wire is suspended vertically from the ceiling and a mass is hung from bottom end. Consider the following statements assuming that the proportional limit of the wire is not exceeded.
    (A) If the length of the wire is doubled, the strain in the wire doubles
    (B) If the area of cross section of the wire is doubled, the strain in the wire doubles
    (C) If the hung mass is doubled, the strain in the wire doubles
    
    Of the above statements
1. (1) only (A) is true
2. (2) only (B) is true
3. (3) only (C) is true
4. (4) only (A) and (C) are true
5. (5) only (B) and (C) are true
6. Answer with explanation

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A/L 2001 Physics MCQs: 1 - 10 | 11 - 20 | 21 - 30 | 31 - 40 | 41 - 50 | 51 - 60