41.
The circuit contains three ammeters A1, A2 and A3 with readings of A2 and A3 shown as indicated in the diagram. Determine the reading of A1.
- A. 2A
- B. 3A
- C. 5A
- D. 8A
42. Which of the following statements about magnetic lines of force is not correct? They
- A. pass through even non-magnetic materials
- B. run from the north pole to the south pole
- C. are in a state of tension and tend to be shorted
- D. intersect one another
43. In which of the following activities is an induction coil not useful?
- A. Investigation of high voltages
- B. Study of electric discharge
- C. Operation of X-ray tubes
- D. A.C. power transmission
44. In a series R-L-C circuit, R = 10Ω, Xc= 4Ω and XL = 9Ω. The impedance of the circuit is
- A. 4.1Ω
- B. 5.0Ω
- C. 10.8Ω
- D. 11.2Ω
45. 
A student uses two compass needles to investigate the magnetic field around a bar magnet. Which of the following diagrams show the correct directions of the needles?
- A. A
- B. B
- C. C
- D. D
46.
Which of the following is emitted in a process of natural radioactivity?
- A. α– particles and – particles
- B. α– particles and X-rays
- C. – particles and X-rays
- D. – rays and X-rays
47. In which of the following situations is photoelectric effect employed?
I. Automatic devices for switching on light at dusk
II. Automatic doors in departmental stores
III. Automatic devices for switching on air conditioners
IV. Automatic voltage stabilizers
- A. I, II and IV only
- B. I, III and IV only
- C. III and IV only
- D. I and II only
48. Which of the following radiations has the longest wavelength?
- A. Gamma ray
- B. Radio wave
- C. Infrared ray
- D. X-ray
49. In which of the following fields is radioisotopes not used?
- A. Medicine
- B. Oil industry
- C. Agriculture
- D. Weather forecast
50. A nuclide is represented by \(_{32}^{70}B\). Determine its neutron-proton ratio
- A. 0.5
- B. 0.8
- C. 1.2
- D.1.5
