M-3 Electrical Final Practice Test [52 Question and 65 Minutes]

Module 03. Electrical

Final Practice Test

  

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1. In what equipment is a photon radiated when an electron leaves a hole ?
   1.   LED
   2.   Photo-cell
   3.   Photo diode
2. What is the maximum number of electrons in shell N of an atom?
   1.   18
   2.   32
   3.   16
3. When an atom loses or gains an electron it is called ?
   1.   a molecule
   2.   an ion
   3.   a current
4. The valence electron is ?
   1.   the electron in outer shell of atom
   2.   the electron in inner shell of atom
   3.   a positive electron
5. Faraday's Law States that?
   1.   the magnitude of the EMF is directly proportional to the magnetic flux
   2.   the magnitude of the EMF is indirectly proportional to the magnetic flux
   3.   the magnitude of the EMF is directly proportional to the rate of change of flux
6. Which of the following is 1 Amp?
   1.   1000 kA
   2.   1000 mA
   3.   1000 μA
7. Ohm's law states that ?
   1.   resistance = current divided by e.m.f
   2.   current = e.m.f. divided by resistance
   3.   e.m.f. = current divided by resistance
8. The SI unit of work is ?
   1.   Joules per metre
   2.   Kilogram metres-force
   3.   Joules per second (Watts)
9. Electromotive force is measured in?
   1.   Watts
   2.   Ohms
   3.   Volts
10. The basis for transformer operation in the use of alternating current is mutual?
    1.   inductance
    2.   capacitance
    3.   reactance
11. The S.I. unit of magnetic flux density is the ?
    1.   Tesla
    2.   Weber
    3.   Henry
12. A shunt is used with?
    1.   a voltmeter
    2.   an ammeter
    3.   an ohmmeter
13. The symbol for flux density is?
    1.   MMF
    2.   H
    3.   B
14. One purpose of the commutator is to ?
    1.   switch the direction of current flow every two cycles
    2.   switch the direction of current flow every cycle
    3.   switch the direction of the current flow every half cycle
15. The rotating part of a motor/generator is called ?
    1.   commutator
    2.   armature
    3.   yoke
16. What is the purpose of the capacitor used in a single phase AC motor ?
    1.   Smoothing
    2.   Provides a high starting torque
    3.   Changing direction of motor
17. In a two-phase induction motor there are ?
    1.   2 poles
    2.   3 poles
    3.   4 poles
18. In a synchronous motor, when the motor is running the slip is?
    1.   5%
    2.   0%
    3.   100%
19. In a 3 phase motor, if 1 phase is lost, the motor ?
    1.   runs at 2 thirds speed
    2.   runs at 1 third speed
    3.   remains at the same speed
20. An AC generator is rated at 30 kVA at 0.8 Power Factor: this means that the maximum continuous output should not exceed?
    1.   30 KW
    2.   24 KW
    3.   37.5 KW
21. Delta wound line current is ?
    1.   root 3 * phase current
    2.   equal to phase current
    3.   less than the phase current
22. Power factor of a generator is ?
    1.   sin ø
    2.   tan ø
    3.   cos ø
23. The 'A' phase of a three phase power system is colour coded?
    1.   blue
    2.   red
    3.   yellow
24. In a 2 phase generator, how far apart are the windings electrically?
    1.   90°
    2.   180°
    3.   45°
25. Band pass filter in a circuit?
    1.   allows frequencies above a cut-off frequency to pass
    2.   allows frequencies below a cut-off frequency to pass
    3.   only allows a narrow band of frequency to pass
26. A capacitor in series and inductor in parallel make what kind of filter?
    1.   Band pass
    2.   High pass
    3.   Low pass
27. Which is a high-pass filter ?
    1.   Π type with series C and L
    2.   L type with series C and shunt L
    3.   L type with series L and shunt C
28. Aircraft autotransformers are of what type?
    1.   Open core
    2.   Twin core
    3.   Laminated core
29. A 3-phase star-delta wound transformer gives?
    1.   30° phase shift
    2.   90° phase shift
    3.   no phase shift
30. An autotransformer windings are?
    1.   wired in parallel
    2.   on separate formers
    3.   connected
31. What causes a transformer to be noisy ?
    1.   High coil resistance
    2.   An air gap in the core
    3.   High core losses
32. Which of the following would be used to calculate transformer turns ratio?
    1.   primary turns ÷ secondary turns
    2.   primary turns × secondary turns
    3.   secondary turns ÷ primary turns
33. Eddy currents in a transformer can be reduced by ?
    1.   laminations
    2.   using a single solid piece of metal
    3.   using a special non metallic material
34. A step up transformer has ?
    1.   three windings
    2.   one winding
    3.   two windings
35. In this circuit applied voltage is ?
    1.   V = IXL
    2.   V = IXC
    3.   V = I/R
36. The Sine wave signals of a circular time base are ?
    1.   phase separated by 90°
    2.   in phase
    3.   phase separated by 180°
37. The controlling wave in a CRT is ?
    1.   sawtooth
    2.   sinusoidal
    3.   square
38. If the frequency is increased in an AC circuit of pure resistance, the effect is?
    1.   increased resistance
    2.   decreased resistance
    3.   nothing
39. The average value of 100 volts peak AC is ?
    1.   141.4 volts
    2.   63.7 volts
    3.   70.7 volts
40. Frequency (Hz) is the number of cycles per ?
    1.   minute
    2.   revolution
    3.   second
41. A parallel circuit at resonance has?
    1.   maximum impedance
    2.   zero impedance
    3.   minimum impedance
42. Prolonged reactive sparking in a DC generator could damage the?
    1.   pole pieces
    2.   commutator
    3.   armature
43. Lines of magnetic flux pass from ?
    1.   South to North
    2.   East to West
    3.   North to South
44. The unit of flux is the ?
    1.   Weber
    2.   Ampere turns
    3.   Ampere turns / metre
45. The lines of magnetic flux from a magnet will?
    1.   attract each other
    2.   repel each other
    3.   have no effect upon each other
46. Ferromagnetic materials can be magnetized ?
    1.   within a band of temperatures
    2.   above a certain temperature
    3.   below a certain temperature
47. One microfarad is?
    1.   1 * 10-6 farads
    2.   1 * 1012 farads
    3.   1 * 10-12 farads
48. A capacitor has Brown, Black and Orange bands. It's value is ?
    1.   10 picofarads
    2.   10 nanofarads
    3.   100 picofarads
49. The charge on a capacitor is expressed as?
    1.   the ratio Q/V
    2.   the product Q * V
    3.   the product C * V
50. One Picofarad is ?
    1.   1 * 1012 farad
    2.   1 * 10-6 farad
    3.   1 * 10-12 farad
51. In a power circuit, the purpose of an inductor is?
    1.   to dampen power surges
    2.   to dampen current surges
    3.   to dampen voltage Surges
52. A thyristor ?
    1.   has a positive temperature coefficient
    2.   if energized on, will switch on a circuit
    3.   if energized on, will switch off a circuit