Module 3 Electrical Final Practice Exam (52 Questions 65 Min)

 

Module - 3 Electrical

Final Practice Exam

  

 

1. The rotating part of a motor/generator is called?
   1.   commutator
   2.   armature
   3.   yoke
2. What is the purpose of the capacitor used in a single phase AC motor ?
   1.   Changing direction of motor
   2.   Provides a high starting torque
   3.   Smoothing Troque
3. The controlling phase on a two phase motor is of a ?
   1.   variable amplitude
   2.   fixed amplitude
   3.   direct current
4. In a two-phase induction motor there are ?
   1.   2 poles
   2.   4 poles
   3.   3 poles
5. In a synchronous motor, when the motor is running the slip is ?
   1.   100%
   2.   5%
   3.   0%
6. A capacitor in a single phase motor is to ?
   1.   prevent sparking at the switch
   2.   provide smoothing
   3.   provide a phase shift
7. Calculate the speed of a 400 Hz, 4 pole machine ?
   1.   6000 rpm
   2.   12,000 rpm
   3.   8000 rpm
8. A three-phase motor has the windings ?
   1.   90° apart
   2.   180°apart
   3.   120° apart
9. In an aircraft brushless alternator the armature is ?
   1.   star wound
   2.   delta wound
   3.   in series with the field
10. In a 2 phase generator, what angle are the phases to each other ?
    1.   0°
    2.   180°
    3.   90°
11. The SI unit of capacitance is ?
    1.   Farad
    2.   Volt
    3.   Ohm
12. Germanium and silicon have how many electrons in their outer shell?
    
    1.   8
    2.   6
    3.   4
13. A semi-conductor will have?
    
    1.   two electrons in the outer shell
    2.   four electrons in the outer shell
    3.   eight electrons in the outer shell
14. The symbol “Ω” represents ?
    1.   Watt
    2.   Ohm
    3.   Volt
15. An ammeter is always connected in?
    1.   Series
    2.   Parallel
    3.   Neither
16. A voltmeter is always connected in?
    1.   Series
    2.   Barometer
    3.   Both
17. Ohm’s law states that ?
    1.   R = V + I
    2.   V = I × R
    3.   I = R × V
18. Which of the following is 1 Amp?
    
    1.   1000 mA
    2.   1000 kA
    3.   1000 μA
19. The S.I. unit of magnetic flux density is the?
    
    1.   Henry
    2.   Weber
    3.   Tesla
20. The property of a material to accept lines of flux is called?
    
    1.   retentivity
    2.   reluctance
    3.   permeability
21. What is the SI unit of conductance?
    
    1.   Ohm-metre
    2.   Ohm
    3.   Siemen
22. What is the SI unit of resistivity ?
    
    1.   Ohms
    2.   Ohms/metre
    3.   Ohm metre
23. A thermocouple indicator is basically a type of ?
    1.   millivoltmeter
    2.   milliammeter
    3.   milliohmeter
24. A battery rated at 40 Ah will supply 200 mA for ?
    1.   20 hours
    2.   200 hours
    3.   5 hours
25. Two 12V 40 amp hour batteries connected in parallel will produce ?
    1.   12V 80 ah
    2.   24V 80 ah
    3.   24V 40 ah
26. In a mercury cell the steel casing is ?
    1.   The negative terminal
    2.   the positive terminal
    3.   Neither
27. The electrolyte in a nicad battery is ?
    1.   Cadmium hydroxide
    2.   Nickel hydroxide
    3.   Potassium hydroxide
28. A galvanometer measures ?
    1.   megohms
    2.   milliamps
    3.   millivolts
29. If voltage is 100V, resistance is 25 ohms, what is the current ?
    1.   2500 amperes
    2.   0.4 amperes
    3.   4 amperes
30. In a balanced Wheatstone bridge, across the centre of the bridge there is?
    1.   Current and voltage at maximum
    2.   No current flow
    3.   No voltage present at either end
31. Total resistance in a parallel resistor circuit, of R1 and R2 is ?
    1.   1/RT = 1/R1 + 1/R2
    2.   1/RT = (R1 * R2) ÷ (R1 + R2)
    3.   RT = 1/R1 + 1/R2
32. A 47 kilohm resistor has the following colour code ?
    1.   Orange, Violet, Red
    2.   Red, Orange, Yellow
    3.   Yellow, Violet, Orange
33. The phase difference between current and voltage in a pure inductive circuit is ?
    1.   0°
    2.   90°
    3.   180°
34. The reactance of a capacitor decreases when ?
    1.   Frequency increases
    2.   Frequency decreases
    3.   Capacitance decreases
35. When a conductor moves through a magnetic field, an EMF is induced due to ?
    1.   Electromagnetic induction
    2.   Mutual induction
    3.   Electrostatic induction
36. Lenz’s law states that ?
    1.   Induced current flows only in one direction
    2.   Induced EMF aids the cause producing it
    3.   Induced EMF opposes the cause producing it
37. In a transformer, eddy current losses can be reduced by ?
    1.   Increasing core size
    2.   Using laminated core
    3.   Using solid iron core
38. The primary purpose of a rectifier is to ?
    1.   Step up voltage
    2.   Convert DC to AC
    3.   Convert AC to DC
39. Kirchhoff’s voltage law states that ?
    1.   Total current entering equals current leaving
    2.   Total voltage around a loop equals zero
    3.   Power is equal to VI
40. The instrument used to measure insulation resistance is?
    1.   Voltmeter
    2.   Megger
    3.   Ohmmeter
41. One Picofarad is ?
    1.   1 * 10-6 farad
    2.   1 * 10-12 farad
    3.   1 * 1012 farad
42. Magnetic inclination is the least at the ?
    1.   poles
    2.   equator
    3.   isoclines
43. The unit of flux is the ?
    1.   Ampere turns / metre
    2.   Ampere turns
    3.   Weber
44. The symbol for flux density is ?
    1.   B(capital)
    2.   H(capital)
    3.   ø(phy)
45. If the rate of change of current is halved, mutual inductance will ?
    1.   Halve
    2.   Stay the same
    3.   Double
46. The electromagnetic brake coil in an actuator would be energised ?
    1.   only when the actuator is running
    2.   all the time in flight
    3.   only at the instant of starting and stopping
47. One purpose of a growler test is to determine the presence of ?
    1.   An out-of-round commutator
    2.   A broken field lead
    3.   A shorted armature
48. A series wound DC motor, the field has ?
    1.   many turns of thin wire
    2.   few turns of thick wire
    3.   few turns of thin wire
49. The voltage output of a generator is controlled by ?
    1.   varying the current of the output
    2.   varying the resistance of the output
    3.   varying the current of the field
50. A 6 pole wave-wound generator has ?
    1.   2 brushes
    2.   3 brushes
    3.   6 brushes
51. Commutator ripple can be reduced by ?
    1.   a resistor in series with the armature
    2.   increasing generator frequency
    3.   the use of a ripple filter
52. A shunt motor ?
    1.   is constant speed
    2.   has high starting torque
    3.   gives constant torque with variations in speed

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