Module 3 - Question Bank - IGNORE Flashcards
1
Q
- A capacitor is fully charged after 25 seconds to a
battery voltage of 20 Volts. The battery is replaced with a
short circuit. What will be the voltage across the capacitor
after one time constant?
a) 12.64 volts
b) 7.36 volts
c) 0 volts
A
b) 7.36 volts
2
Q
- The voltage rating of a capacitor is
a) the max voltage that can be constantly applied
b) the min voltage required to charge
c) the normal operating voltage
A
a) the max voltage that can be constantly applied
3
Q
- The relative permittivity of a capacitor is
a) the relative permittivity of the dielectric in relation to
a vacuum
b) the permittivity of dielectric in relation to dry air
c) the permittivity of the dielectric
A
a) the relative permittivity of the dielectric in relation to
a vacuum
4
Q
- Magnetic inclination is the least at the
a) poles
b) equator
c) isoclines
A
b) equator
5
Q
- Ferromagnetic materials can be magnetized
a) within a band of temperatures
b) above a certain temperature
c) below a certain temperature
A
c) below a certain temperature
6
Q
- Faradays Law States that
a) the magnitude of the EMF is directly proportional to the rate of change of flux
b) the magnitude of the EMF is indirectly proportional to the rate of change of flux
c) the magnitude of the EMF is directly proportional to the magnetic flux
A
a) the magnitude of the EMF is directly proportional to the rate of change of flux
7
Q
- To reduce eddy currents in a transformer you would
a) reduce the thickness of laminations in the magnetic core
b) Increase the thickness of laminations in the magnetic core
c) Reduce the number of turns on the primary winding
A
a) reduce the thickness of laminations in the magnetic core
8
Q
- A transformer has an input of 400V and a ratio of 2:1.
If the transformer is delta / star wound, what will the line
voltage output be?
a) 115V
b) 200V
c) 346V
A
c) 346V
9
Q
- What is the phase difference in a circuit with 100V,
drawing 0.5 amps, consuming 50 Watts?
a) 45°
b) 90°
c) 0°
A
c) 0°
10
Q
- In an A.C circuit, what happens if frequency is
reduced?
a) Capacitive elements may be damaged
b) Inductive elements may be damaged
c) There will be no effect
A
b) Inductive elements may be damaged
11
Q
- A Transformer with 115v primary voltage and a ratio
of 5:1 is supplying a landing light (load 24v 45 amps) is
used, what is the current drawn?
a) 205 amps
b) 9 amps
c) 4.5 amps
A
b) 9 amps
12
Q
- A Transformer has 4500 secondary turns and 750
primary turns. Its turns ratio is
a) 1:6
b) 6:1
c) 1/6
A
b) 6:1
13
Q
- Two inductive coils are placed in close proximity with
each other at 90 degrees. The number of flux linkages is
a) 0
b) maximum positive
c) maximum negative
A
a) 0
14
Q
- A high pass filter will?
a) allow frequencies above a certain value to pass
b) allow frequencies below a certain value to pass
c) allow frequencies within a range to pass
A
a) allow frequencies above a certain value to pass
15
Q
- If you apply this waveform to this circuit, what is the
output across the capacitor?
a) Zero
b) Pulsed negative
c) Pulsed positive
A
c) Pulsed positive
16
Q
- What value is the same as the equivalent D.C.
heating effect?
a) Root Mean Square
b) Average
c) Peak
A
a) Root Mean Square
17
Q
- What is the relationship between the voltage and the
current in an A.C circuit containing resistance &
inductance?
a) Current leads voltage by up to 90°
b) Current lags voltage by up to 90°
c) Current lags voltage by 90°
A
b) Current lags voltage by up to 90°
18
Q
- What shape is the waveform when the input pulse
and the time base are unequal?
a) Square
b) Rectangular
c) Saw tooth
A
b) Rectangular
19
Q
- A sine wave has 5 amps RMS value. What is the
peak value?
a) 6.37 amps
b) 7.07 amps
c) 10 amps
A
b) 7.07 amps
20
Q
- In this circuit
a) current leads voltage
b) current lags voltage
c) current = voltage
A
a) current leads voltage
21
Q
- Decreasing the field current in a shunt motor will
a) increase speed and decrease torque
b) increase speed and increase torque
c) decrease speed and increase torque
A
b) increase speed and increase torque
22
Q
- Power factor relates to
a) true power and apparent power
b) KW and KVAR
c) horsepower and Watts
A
a) true power and apparent power
23
Q
- In a delta-connected generator
a) line volts = phase volts, line current = root 3 times phase current.
b) line volts = phase volts, line current = phase current divided by root 3
c) line voltage = root 3 times phase voltage, line current = phase current
A
a) line volts = phase volts, line current = root 3 times phase current.
24
Q
- If current lags voltage by 90°, the circuit is
a) capacitive
b) resistive
c) inductive
A
c) inductive
25
Q
- In a 3 phase motor, if 1 phase is lost, the motor
a) remains at the same speed
b) runs at 1 third speed
c) runs at 2 thirds speed
A
a) remains at the same speed
26
Q
- A three-phase motor has the windings
a) 120° apart
b) 90° apart
c) 180°apart
A
a) 120° apart
27
Q
- When measuring the phase and line voltages of a generator, it was found that line and phase voltages were equal. The generator is?
a) delta wound
b) star wound.
c) either delta or star wound
A
a) delta wound
28
Q
- To change the direction of a 3-phase induction motor
you would
a) swap two of the stator connections
b) swap all of the input connections
c) remove one of the input connections
A
a) swap two of the stator connections
29
Q
- To calculate generator output you need to know the
a) armature speed and number of series conductors
b) armature speed and number of parallel conductors
c) armature speed and field strength
A
c) armature speed and field strength
30
Q
- In a shunt motor, if you reverse both field current and armature current, the motor will
a) stop
b) change direction
c) continue to run in the same direction
A
c) continue to run in the same direction
31
Q
- The permanent magnet in an A.C generator induces
a) A.C. in the exitor generator
b) D.C. in the exitor generator
c) A.C. in the main generator
A
a) A.C. in the exitor generator
32
Q
- What does the following circuit represent?
a) Integrator
b) Low pass filter
c) Differentiator
A
c) Differentiator
33
Q
- What charge does the nucleus of an atom possess?
a) Positive
b) Negative
c) Neutral
A
a) Positive
34
Q
- What is the maximum number of electrons in shell N
of an atom?
a) 16
b) 32
c) 18
A
b) 32
35
Q
- Two 10V, 20 Ah batteries are connected in parallel and connected across a 10-ohm load. How long could they supply normal current before the voltage begins to decay?
a) 20 hours
b) 4 hours
c) 40 hours
A
c) 40 hours
36
Q
- A 10 V battery supplies a resistive load of 10 ohms for
1 minute. What is the power supplied
a) 100 W
b) 10 VA
c) 10 W
A
c) 10 W
37
Q
- A 10V battery supplies a resistive load of 10 ohms for
1 minute. What is the work done?
a) 60J
b) 10J
c) 600J
A
c) 600J
38
Q
- Three capacitors 10 microfarads, 10 nanofarads and
10 millifarads are connected in parallel. What is the total
capacitance?
a) 10.01001mF
b) 111mF
c) 1.001001mF
A
a) 10.01001mF
39
Q
- If a 1mF capacitor has a potential difference across it of 5V what is the energy stored?
a) 12.5 J
b) 12.5 mJ
c) 25 mJ
A
b) 12.5 mJ
40
Q
- A capacitor is fully charged after 25 seconds to a battery voltage of 20 V. The battery is replaced with a short circuit. What will be the voltage across the capacitor after 1 time constant?
a) 12.64 V
b) 7.36 V
c) 0 V
A
b) 7.36 V
41
Q
- Glass is an example of a
a) paramagnetic material
b) diamagnetic material
c) coercive material
A
b) diamagnetic material
42
Q
- Which of the following is absolute permeability?
a) µ
b) µo
c) µr
A
a) µ
43
Q
- A solenoid of 10 turns per meter carries a current of
5A. If the current is reduced to 2.5A, how many turns
would be required to maintain the same magnetic field?
a) 5
b) 50
c) 20
A
c) 20
44
Q
- The point of coercivity occurs when the
a) magnetizing force applied causes the material to become magnetically saturated.
b) magnetic flux is zero even though a magnetizing force is being applied.
c) magnetizing force reaches a peak positive or negative value.
A
b) magnetic flux is zero even though a magnetizing force is being applied.
45
Q
- What is the mutual inductance if two coils of 10mH and 500mH have 90% of the flux transferred from one to the other?
a) 4.5mH
b) 459mH
c) 63mH
A
c) 63mH
46
Q
- An inductor has 1,000 turns of wire and a cross sectional area of 0.001m2. If the core has a permeability of 0.000,001 and the coil is 0.1m what is the value of the inductor
a) 10mH
b) 100microH
c) 100mH
A
a) 10mH
47
Q
- Three inductors 10 mH, 5 mH and 20 mH are connected in parallel. What is the total inductance?
a) 35mH
b) 2.86mH
c) Without knowing the coupling factor the total inductance cannot be found
A
b) 2.86mH
48
Q
- If the current reaches a maximum through an inductor of 2A in 15 secs, what is the current after 3 secs?
a) 1.26A
b) 0.63A
c) 1A
A
a) 1.26A
49
Q
- If the phase voltage in a star connected generator is 200V what will be the line voltage?
a) 115V
b) 200V
c) 346V
A
c) 346V
50
Q
- A generator is labeled as having 115V/200V, 20A and PF 0.8. What is the apparent power in each line that the generator can produce?
a) 2.3kW
b) 2.3kVA
c) 4kVA
A
c) 4kVA
51
Q
- A starter generator has a
a) low resistance series field and a low resistance shunt field
b) low resistance series field and a high resistance shunt field
c) high resistance series field and a low resistance shunt field
A
b) low resistance series field and a high resistance shunt field
52
Q
- Thermocouple harnesses are made from the same materials as the thermocouple so that
a) they will not corrode
b) mini junctions are not formed
c) the resistance is not increased beyond limits
A
b) mini junctions are not formed
53
Q
- An oxygen molecule is made up of
a) two oxygen atoms sharing electrons
b) two oxygen atoms sharing neutrons
c) two oxygen atoms sharing protons
A
a) two oxygen atoms sharing electrons
54
Q
- A capacitor in a single phase AC motor is to
a) prevent spikes
b) block DC
c) provide a phase shift
A
c) provide a phase shift
55
Q
- The slip speed of an induction motor is
a) stator speed - rotor speed
b) stator speed + rotor speed
c) stator speed / rotor speed
A
a) stator speed - rotor speed
56
Q
- The primary winding of a 3-phase transformer
a) is delta wound
b) is star wound
c) could be either delta or star wound
A
c) could be either delta or star wound
57
Q
- The symbol for flux density is
a) H
b) B
c) ø
A
b) B
58
Q
- A galvanometer measures
a) millivolts
b) megohms
c) milliamps
A
c) milliamps
59
Q
- A battery rated at 40 Ah will supply 200 mA for
a) 200 hours
b) 5 hours
c) 20 hours
A
a) 200 hours
60
Q
- The unknown resistance R in the wheatstone bridge shown is
a) 1 ohm
b) 4 ohms
c) 16 ohms
A
b) 4 ohms
61
Q
- Which of the following materials is easiest to
magnetize?
a) Soft iron
b) High grade steel
c) Cast iron
A
a) Soft iron
62
Q
- AC generators are rated in
a) kVARs
b) kW
c) kVA
A
c) kVA
63
Q
- To find which end of an electromagnet is the north pole, use the
a) Fleming’s Left Hand Rule
b) Right Hand Clasp Rule
c) Cork Screw Rule
A
b) Right Hand Clasp Rule
64
Q
- A capacitor with double the area and double the dielectric thickness will have
a) double the capacitance
b) half the capacitance
c) the same capacitance
A
c) the same capacitance
65
Q
- In a transformer, if the rate of change of current increases, the mutual inductance will
a) increase
b) decrease
c) remain the same
A
c) remain the same
66
Q
- If the brake coil on an actuator motor goes open circuit, the actuator will
a) over-ride its mechanical stops
b) stop
c) run slower
A
b) stop
67
Q
- The frequency of the output of a 4 pole generator is 400 Hz. The generator is turning at
a) 12000 RPM
b) 6000 RPM
c) 3000 RPM
A
a) 12000 RPM
68
Q
- What is the wave shape of the x-axis input of a traversing oscilloscope image?
a) square
b) rectangular
c) triangular
A
c) triangular
69
Q
- An inductance/resistance motor is
a) better than a capacitance motor
b) restricted to low loads only
c) less efficient than a capacitance motor
A
c) less efficient than a capacitance motor
70
Q
- The voltage at point A is
a) 7 V
b) 21 V
c) 28 V
A
a) 7 V
71
Q
- A 4:1 step down transformer draws 115 V and 1 A.
The output power will be
a) 28.5 V at 4 A
b) 28.5 V at 16 A
c) 460 V at 0.25 A
A
a) 28.5 V at 4 A
72
Q
- The voltage induced in the stator of an AC generator
is produced by
a) a fixed magnetic field
b) a rotating magnetic field
c) an alternating field
A
b) a rotating magnetic field
73
Q
- A low frequency supply
a) may damage inductive components
b) will have no effect on inductive components
c) will make the circuit operate faster due to the reduced impedance
A
a) may damage inductive components
74
Q
- A zinc-carbon battery life depends upon
a) the purity of the carbon rod
b) the amount of zinc
c) the amount of the electrolyte paste
A
b) the amount of zinc
75
Q
- When checking the s.g. of the electrolyte in a lead acid battery, you should
a) check all cells because they may be different
b) check only the no. 1 cell because it is the master cell
c) check any cell because they will all be the same
A
a) check all cells because they may be different
76
Q
- If electrons are added to an atom it becomes
a) a positive ion
b) a negative ion
c) a neutral ion
A
b) a negative ion
77
Q
- An element whose atoms have fewer than 4 electrons
in their valency shell are
a) good conductors
b) good insulators
c) semiconductors
A
a) good conductors
78
Q
- In a purely resistive AC circuit, the current vector is
a) in phase with the voltage vector
b) +90^ out of phase with the voltage vector
c) -90^ out of phase with the voltage vector
A
a) in phase with the voltage vector
79
Q
- The PD at the terminals of an open circuit battery with a small internal resistance will be
a) more than the EMF
b) less than the EMF
c) the same as the EMF
A
c) the same as the EMF
80
Q
- The diagram shows a 200 V long shunt generator. What is the voltage dropped across the series resistor?
a) 200 V
b) 0.12 V
c) 0.2 V
A
b) 0.12 V
81
Q
- An electrolytic capacitor is used where
a) minimum losses are essential
b) there is a polarized input
c) high frequency AC is used
A
b) there is a polarized input
82
Q
- If a connection to an AC motor is disconnected, the motor will
a) slow down and stop
b) continue to run
c) stop
A
b) continue to run
83
Q
- A band stop filter
a) stops a narrow range of frequencies
b) stops frequencies either side of a narrow range
c) attenuates frequencies either side of a narrow range
A
a) stops a narrow range of frequencies
84
Q
- This is a diagram of a
a) band pass filter
b) high pass filter
c) low pass filter
A
c) low pass filter
85
Q
- When comparing the average values of an AC generator output, to the peak values
a) average voltage = same as the peak voltage
b) average voltage = 0.63 x peak voltage
c) average voltage = 0.707 x peak voltage
A
b) average voltage = 0.63 x peak voltage
86
Q
- A parallel circuit at resonance has
a) maximum impedance
b) minimum impedance
c) zero impedance
A
a) maximum impedance
87
Q
- A resistor dissipates 80 Watts. If it runs for 4 hours 15 minutes, how much energy is dissipated in total?
a) 1.224 MJ
b) 20.4 kJ
c) 191.25 J
A
a) 1.224 MJ
88
Q
- The earth lead of a 24 V equipment is 0.5 ohm resistance and carries 80 A. How much power does it dissipate?
a) 3.2 kW
b) 1.152 kW
c) 1.92 kW
A
a) 3.2 kW
89
Q
- What must you do to make a 3 F capacitor circuit into a 2 F circuit?
a) Put a 1 F capacitor in series
b) Put a 2 F capacitor in parallel
c) Put a 6 F capacitor in series
A
c) Put a 6 F capacitor in series
90
Q
- The time required to fully charge a 1 µF capacitor in series with a 100k ohm resistor is
a) 100 ms
b) 1 s
c) 100 s
A
a) 100 ms
91
Q
- A 10 ohm resistor has a 14.14 V peak drop across it. What power is dissipated?
a) 19.99 W
b) 10 W
c) 1.414 W
A
b) 10 W
92
Q
- This is a symbol for
a) a voltage dependent resistor
b) a variable differential resistor
c) a visual display rectifier
A
a) a voltage dependent resistor
93
Q
- If a generator speed is halved and the field strength is doubled, the voltage output will be
a) halved
b) doubled
c) unchanged
A
c) unchanged
94
Q
- Point A on the armature of the generator shown is producing
a) maximum current
b) minimum current
c) zero current
A
a) maximum current
95
Q
- An accumulation of hydrogen on the plates of a battery is known as
a) hydration
b) polarization
c) ionization
A
b) polarization
96
Q
- What is the power dissipated in a 500 ohm resistor with a 3A flow?
a) 1.5 kW
b) 4.5 kW
c) 750 kW
A
b) 4.5 kW
97
Q
- Which of the following is 1 Amp?
a) 1000 mA
b) 1000 μA
c) 1000 kA
A
a) 1000 mA
98
Q
- A paramagnetic material has a relative permeability of
a) greater than unity
b) less than unity
c) zero
A
a) greater than unity
99
Q
- What part of a battery is covered in hydrogen during polarization?
a) Cathode
b) Anode
c) Both the anode and the cathode
A
a) Cathode
100
Q
- Electricity conducts through
a) solids only
b) solids and liquids
c) vacuum
A
b) solids and liquids
101
Q
- The term that describes the combined resistive forces in an AC circuit is
a) impedance
b) resistance
c) total resistance
A
a) impedance
102
Q
- How can the direction of rotation of a DC electric motor be changed
a) reverse the electrical connections to either the field or armature windings
b) interchange the wires which connect the motor to the external power source
c) rotate the positive brush one commutator segment
A
a) reverse the electrical connections to either the field or armature windings
103
Q
- An example of a good electrical insulator is
a) glass
b) aluminium
c) mercury
A
a) glass
104
Q
- The only practical method of maintaining a constant voltage output from an aircraft generator under varying conditions of speed and load is to vary the
a) strength of the magnetic field
b) number of conductors in the armature
c) speed at which the armature rotates
A
a) strength of the magnetic field
105
Q
- An accumulation of hydrogen on the plates of a battery is known as
a) hydration
b) polarization
c) ionization
A
b) polarization
106
Q
- Which of the following is most likely to cause thermal runaway in a nickel-cadmium battery
a) excessive current draw from the battery
b) high current charging of the battery to more than 100 percent of its capacity
c) a high internal resistance condition
A
b) high current charging of the battery to more than 100 percent of its capacity
107
Q
- Electric motors are often classified according to the method of connecting the field coils and armature. Aircraft engine starter motors are generally of which type
a) compound
b) shunt (parallel)
c) series
A
c) series
108
Q
- If a heavy mechanical load is removed from a series motor
a) the speed will decrease and the armature current will decrease
b) the speed will increase and the armature current will decrease
c) the speed will increase and the armature current will increase
A
b) the speed will increase and the armature current will decrease
109
Q
- Static charges remaining in an aircraft are dissipated by
a) the use of a conducting type nose wheel
b) bonding the aircraft to a refuel tanker
c) earthing the aircraft as soon as possible
A
a) the use of a conducting type nose wheel
110
Q
- Total resistance in parallel for R1 and R2 is
a) RT = (R1 x R2) ÷ (R1 + R2)
b) RT = 1/R1 + 1/R2
c) 1/RT = 1/R1 + 1/R2
A
a) RT = (R1 x R2) ÷ (R1 + R2)
111
Q
- The quill drive on an aircraft generator
a) makes possible the use of roller
b) damps out any commutator ripple
c) damps out vibrations
A
c) damps out vibrations
112
Q
- The method of ascertaining the voltage of a standard aircraft lead-acid battery is by checking
a) the voltage on open circuit
b) the voltage with rated load switched ON
c) the voltage off load
A
b) the voltage with rated load switched ON
113
Q
- If the correct supply were connected to a DC shunt motor which had lost its residual magnetism it would
a) fail to run
b) run in the reverse direction
c) run normally
A
c) run normally
114
Q
- A loss of electrical insulation results in
a) a short circuit between the supply and earth
b) an open circuit between the supply and earth
c) an open circuit in the supply
A
a) a short circuit between the supply and earth
115
Q
- A DC circuit containing a total resistance of 100 ohms has a current flow of 250 mA. The power dissipated in the circuit is
a) 0.4 watts
b) 6.25 watts
c) 5 watts
A
b) 6.25 watts
116
Q
- Power is the rate of doing work. It is measured in
a) joules/second
b) watts/second
c) joules x seconds
A
a) joules/second
117
Q
- Ohm’s law states that:
a) e.m.f. = current divided by resistance
b) resistance = current divided by e.m.f.
c) current = e.m.f. divided by resistance
A
c) current = e.m.f. divided by resistance
118
Q
- If the resistance of a resistor which is in series with two other resistors is doubled
a) the current in that resistance is doubled
b) the current in that resistance is halved
c) the volts drop across that resistor increases
A
c) the volts drop across that resistor increases
119
Q
- One purpose of a growler test is to determine the presence of:
a) a shorted armature
b) an out-of-round commutator
c) a broken field lead
A
a) a shorted armature
120
Q
- Through which material will magnetic lines of force pass the most readily?
a) aluminium
b) iron
c) copper
A
b) iron
121
Q
- Electricity conducts through
a) solids only
b) solids and liquids
c) vacuum
A
b) solids and liquids
122
Q
- The secondary coil of a transformer has 1500 turns and 10 Ω resistance. The primary coil has 1 k Ω resistance. How many turns does the primary coil have?
a) 15,000
b) 150,000
c) 1,500,000
A
a) 15,000
123
Q
- Two batteries 12V and 40 Ah each, are in series. What is the total capacity?
a) 12V 80 Ah
b) 24V 80Ah
c) 24V 40 Ah
A
c) 24V 40 Ah
124
Q
- In a star wound primary transformer, how could you wind the secondary winding?
a) star only
b) delta only
c) either delta or star
A
c) either delta or star
125
Q
- The phases in supply to a 2 phase motor are electrically
a) 90 degrees apart from each other
b) 180 degrees apart from each other
c) 120 degrees apart from each other
A
a) 90 degrees apart from each other
126
Q
- A 30 KVA rated generator has a power factor of 0.8. What is its maximum consistent power
a) 30 KW
b) 24 KW
c) 37.5 KW
A
b) 24 KW
127
Q
- A 50 μF capacitor is fed with a current of 25 mA. How long will it take to charge it to 100V?
a) 1 s
b) 0.2 seconds
c) 12 minutes
A
b) 0.2 seconds
128
Q
- The total resistance of the circuit shown is
a) 1.33 Ohms
b) 12 Ohms
c) 3 Ohms
A
c) 3 Ohms
129
Q
- A step up transformer has
a) one winding
b) two windings
c) three windings
A
b) two windings
130
Q
- The three voltages of a three phase generator are connected
a) independently of each other
b) in series with each other
c) in parallel with each other
A
a) independently of each other
131
Q
- E.M.F. in an electric circuit corresponds to what in a magnetic circuit
a) mmf
b) flux
c) reluctance
A
a) mmf
132
Q
- Time constant of an inductor is
a) LR
b) L/R
c) L^2/R
A
b) L/R
133
Q
- Permanent magnets have
a) high reluctance, low coercive force
b) low reluctance, high coercive force
c) high reluctance, high coercive force
A
c) high reluctance, high coercive force
134
Q
- A.C. value that can produce the same heat as D.C. is called
a) r.m.s value
b) average value
c) peak value
A
a) r.m.s value
135
Q
- If a battery has got low internal resistance, then
a) on load voltage will be greater than no load voltage
b) no load voltage will be greater than on load voltage
c) no load voltage will be the same as on load voltage
A
b) no load voltage will be greater than on load voltage
136
Q
- in a parallel R, L, C circuit, the value of the capacitor is quadrupled, then the value of the impedance would
a) reduce
b) increased
c) remain the same
A
a) reduce
137
Q
- In a circuit C = 25 microfarads and the current flow is
40 microamps for 4 seconds. What is the voltage
a) 12.8V
b) 6.4V
c) 3.2V
A
b) 6.4V
138
Q
- A 3, 5 and 2 ohms resistance is connected in series with a 10 V battery. The voltage across the 2 ohms resistor is
a) 10V
b) 2 V
c) 4 V
A
b) 2 V
139
Q
- The power in a circuit when voltage and resistance is given can be found by
a) VxR
b) VxV / R
c) VxVxR
A
b) VxV / R
140
Q
- A piezoelectric device generates electricity through
a) pressure
b) friction
c) light
A
a) pressure
141
Q
- Conventional current flow inside a battery is from
a) anode to cathode
b) cathode to anode
c) either anode to cathode or cathode to anode, depending on the active elements
A
a) anode to cathode
142
Q
- Potentiometers are used as a
a) variable voltage source
b) variable resistor
c) variable current source
A
a) variable voltage source
143
Q
- In a transformer core loss is 200 W and copper loss
is 220W at no load. What is the core loss at full load
a) 200 W
b) 220 W
c) 0 W
A
a) 200 W
144
Q
- Calculate the speed of a 400 Hz, 4 pole machine
a) 12,000 rpm
b) 6000 rpm
c) 8000 rpm
A
a) 12,000 rpm
145
Q
- The purpose of end travel microswitch in a linear actuator is to
a) remain closed and opens at end travel only
b) remain open and closes at end travel only
c) remain open during normal operation and only close if the actuator overruns its stops
A
a) remain closed and opens at end travel only
146
Q
- Linear actuators used in aircraft are of
a) split field series wound type.
b) split field shunt wound type
c) compound wound type
A
a) split field series wound type.
147
Q
- If a generator sparks, a possible reason is
a) The brush springs are loose
b) The brushes have been placed around the magnetic coil
c) Magnetic flux deflecting the EMF
A
a) The brush springs are loose
148
Q
- The charge on a proton is
a) neutral
b) positive
c) negative
A
b) positive
149
Q
- in conventional current flow, what is Fleming’s right hand rule used for
a) Motors
b) Generators
c) Inductors
A
b) Generators
150
Q
- In a capacitive circuit, if the frequency is increased
a) the current increases
b) impedance increases
c) reactance remains the same
A
a) the current increases
151
Q
- Three 12 µF capacitors are in series. The total capacitance is
a) 12 µF
b) 4 µF
c) 36 µF
A
b) 4 µF
152
Q
- A 500 ohm resistor carries a 3 amp current. What is the power dissipated?
a) 5 kW
b) 4.5 kW
c) 500 W
A
b) 4.5 kW
153
Q
- A paramagnetic material has a relative permeability
a) less than unity
b) greater than unity
c) equal to unity
A
b) greater than unity
154
Q
- What is the PD of a circuit which has a 40 mA current and a 1 k ohm resistance?
a) 400 V
b) 4 V
c) 40 V
A
c) 40 V
155
Q
- The time constant of a capacitor is the time
a) for the emf to reach 36.8% of maximum
b) the current to reach 70.7% of maximum
c) to reach maximum current
A
a) for the emf to reach 36.8% of maximum
Note: 36.8% is the TC for discharge, while charging one TC = 63.2%
156
Q
- The secondary winding of a transformer has an impedance of 10 ohms and 1500 turns. For the primary winding to have an impedance of 1 k ohm, how many
turns must it have?
a) 15,000
b) 150,000
c) 1,500,000
A
a) 15,000
157
Q
- A potentiometer has which of the following properties?
a) 3 terminals
b) preset values
c) wire wound
A
a) 3 terminals
158
Q
- A 3 ohm resistor dissipates 27 Watts. How much current flows through it?
a) 3 A
b) 9 A
c) 0.15 A
A
a) 3 A
159
Q
- in a 2 phase generator, how far apart are the windings electrically?
a) 45^
b) 90^
c) 180^
A
b) 90^
160
Q
- The SI unit of work is
a) Joules per second (Watts)
b) Kilogram metres - force
c) Joules per metre
A
b) Kilogram metres - force
161
Q
- in the circuit below, what happens to the total circuit impedance if L is tripled?
a) Increases
b) Remains the same
c) Reduces
A
a) Increases
162
Q
- in a voltaic cell, what is the build-up on the cathode called?
a) Polarization
b) Sulphation
c) Hydration
A
a) Polarization
163
Q
- A sine wave has a periodic time of 0.5 milliseconds. What is the frequency
a) 200 Hz
b) 2 kHz
c) 20 kHz
A
b) 2 kHz
164
Q
- Three branches in a circuit have currents entering of 3A, 4 A and 5 A. A forth branch has 10 A leaving. A fifth branch must have
a) 2A entering
b) 2A leaving
c) 22A leaving
A
b) 2A leaving
165
Q
- Where are the output windings on an AC generator?
a) Stator
b) Rotor with slip rings
c) Rotor with commutator
A
a) Stator
166
Q
- If the field strength of a generator is doubled, and the speed is doubled, the output EMF will
a) quadruple
b) double
c) stay the same
A
a) quadruple
167
Q
- If the rate of change of current is halved, mutual inductance will
a) double
b) stay the same
c) half
A
b) stay the same
168
Q
- If a capacitor of 50 microfarads has a current of 25 mA, how long does it take to charge to 100 V
a) 200 milliseconds
b) 200 seconds
c) 150 seconds
A
a) 200 milliseconds
169
Q
- in a Wheatstone Bridge, the ammeter reads zero, and the variable resistor is adjusted to 5 ohms. Resistor P has a value of 10 ohms and Q has a value of 100 ohms. What is the value of the unknown resistor?
a) 0.5 ohms
b) 5 ohms
c) 50 ohms
A
c) 50 ohms
170
Q
- in a tuned circuit at resonance, the circuit will be
a) inductive
b) resistive
c) capacitive
A
b) resistive
171
Q
- The time constant for an inductor is
a) L/R
b) R/L
c) L x R
A
a) L/R
172
Q
- In a DC motor the pole pairs are
a) imbedded within the field coils
b) part of the armature
c) connected to the brush gear
A
a) imbedded within the field coils
173
Q
- Eddy currents in a transformer core are reduced by
a) decreasing the thickness of the laminates
b) increasing the thickness of the laminates
c) making the core from a solid block
A
a) decreasing the thickness of the laminates
174
Q
- Transformer copper loss on full load is 220 Watts. On half load the loss will be
a) 110 Watts
b) 440 Watts
c) 55 Watts
A
c) 55 Watts
175
Q
- The earth’s magnetic field is greatest at the
a) magnetic poles
b) geographic poles
c) magnetic equator
A
a) magnetic poles
176
Q
- If a 1 ohm circuit produces a 50 W output, the phase
angle is
a) 0^
b) 90^
c) 45^
A
a) 0^
177
Q
- A series wound DC motor, the field has
a) few turns of thick wire
b) few turns of thin wire
c) many turns of thin wire
A
a) few turns of thick wire
178
Q
- What effect do the electrons of one atom have upon the electrons of another atom?
a) They repel each other
b) They attract each other
c) They have no effect on each other
A
a) They repel each other
179
Q
- What is a molecule?
a) The smallest part of a compound
b) The smallest part of an electron
c) The smallest part of an atom
A
a) The smallest part of a compound
180
Q
- A coulomb is
a) one ampere per second
b) one ampere x second
c) one second per ampere
A
b) one ampere x second
181
Q
- in a circuit containing three resistors of equal value connected in parallel, one resistor goes open circuit. The current in the other two resistors will
a) increase
b) decrease
c) remain the same
A
c) remain the same
182
Q
- 20 amperes flow for 20 seconds. How many coulombs has flowed?
a) 400
b) 20
c) 1
A
a) 400
183
Q
- An atom is
a) the smallest part of an element that retains its characteristics
b) the smallest part of a compound that can exist independently
c) the smallest particle of matter
A
a) the smallest part of an element that retains its characteristics
184
Q
- A neutron is a particle which is
a) contained within the nucleus of most atoms
b) orbits the nucleus of the atom
c) contained in the nucleus of all atoms
A
a) contained within the nucleus of most atoms
185
Q
- An electric current is a flow of
a) electrons from a positively charged area to a negatively charged area
b) protons from a positively charged area to a negatively charged area
c) electrons from a negatively charged area to a positively charged area
A
c) electrons from a negatively charged area to a positively charged area
186
Q
- An element could be considered to be a conductor if it has
a) a large number of electrons
b) a large number of electrons in its outer orbit
c) a small number of electrons in its outer orbit
A
c) a small number of electrons in its outer orbit
187
Q
- A volt can be considered to be a
a) unit of electrical pressure
b) quantity of electrical energy
c) unit of electrical power
A
a) unit of electrical pressure
188
Q
- If the resistance of an electrical circuit is increased
a) the voltage will increase
b) the current will increase
c) the current will decrease
A
c) the current will decrease
189
Q
- If 2 coulombs flowed through a circuit in 2 seconds, the circuit would have
a) 2 volts PD
b) 2 amps
c) 1 amp
A
c) 1 amp
190
Q
- In general, increasing the cross sectional area of an electrical cable
a) enables it to carry more current
b) enables it to carry more voltage
c) increases its resistance
A
a) enables it to carry more current
191
Q
- Doubling the running time of an electrical machine would
a) double the joules used
b) double the watts used
c) double the current used
A
a) double the joules used
192
Q
- What is 3.25 volts in millivolts
a) 3.25 millivolts
b) 3,250 millivolts
c) 325,000 millivolts
A
b) 3,250 millivolts
193
Q
- Electromotive force is measured in
a) Watts
b) Ohms
c) Volts
A
c) Volts
194
Q
- Six resistors each of 6 ohms would be
a) 36 ohms in parallel
b) 1 ohm in series
c) 1 ohm in parallel
A
c) 1 ohm in parallel
195
Q
- A capacitor in a single phase motor is to
a) provide a phase shift
b) prevent sparking at the switch
c) provide smoothing
A
a) provide a phase shift
196
Q
- The mass of an atom is contained mainly in the
a) electron
b) nucleus
c) proton
A
b) nucleus
197
Q
- The line voltage from a generator with a delta type connection will be
a) higher than the phase voltage
b) lower than the phase voltage
c) the same as the phase voltage
A
c) the same as the phase voltage
198
Q
- On a linear actuator, the field cutoff coil will be energized when
a) the actuator is running
b) the actuator is not running
c) only as the actuator commences movement
A
a) the actuator is running
199
Q
- Kirchhoff’s law states
a) the algebraic sum of all the voltages entering or leaving a series of components will be equal to zero
b) the algebraic sum of all the currents entering or leaving a series of components will be equal to one
c) the inverse sum of all the voltages entering or leaving a series of components will be equal to one
A
a) the algebraic sum of all the voltages entering or leaving a series of components will be equal to zero
200
Q
- The lines of magnetic flux from a magnet will
a) repel each other
b) attract each other
c) have no effect upon each other
A
a) repel each other
201
Q
- A photozoidal cell produces electricity when subjected to
a) light
b) heat
c) pressure
A
a) light
202
Q
- A thermocouple indicator is basically a type of
a) milliammeter
b) millivoltmeter
c) milliohmeter
A
b) millivoltmeter
203
Q
- An electric motor produces a force of 5 N at a distance of 0.2m from the centre of rotation and rotates at a speed of 100 revs/sec. The motors output is
a) 100 horsepower
b) 628.4 watts
c) 314.2 watts
A
b) 628.4 watts
204
Q
- A potentiometer varies
a) voltage
b) current
c) resistance
A
a) voltage
205
Q
- Starter motors are usually
a) series wound
b) compound wound
c) shunt wound
A
a) series wound
206
Q
- How can it be determined if a transformer winding has some of its turns shorted together?
a) measure the input voltage with an ohmmeter
b) the transformer will get hot in normal operation
c) the output voltage will be high
A
b) the transformer will get hot in normal operation
207
Q
- An advantage of a star connected generator over a delta connected generator is
a) a balance load is guaranteed
b) two potentials are available
c) the line and phase voltages are equal
A
b) two potentials are available
208
Q
- What does a rectifier do?
a) Changes direct current into alternating current
b) Changes alternating current into direct current
c) Reduces voltage
A
b) Changes alternating current into direct current
209
Q
- Two 12V 40 amp hour batteries connected in parallel will produce
a) 24V 80 ah
b) 12V 80 ah
c) 24V 40 ah
A
b) 12V 80 ah
210
Q
- When an atom loses or gains an electron it is called
a) a current
b) an ion
c) a molecule
A
b) an ion
211
Q
- A circuit has a resistance of 50 ohms and an inductance of 0.2 Henry. If it is connected to a 200 volt 50 Hz supply the reactance will be
a) 31.42 ohms
b) 62.84 ohms
c) 6.284 ohms
A
b) 62.84 ohms
212
Q
- A 24-volt source is required to furnish 48 watts to a parallel circuit consisting of four resistors of equal value. What is the voltage drop across each resistor?
a) 12 volts
b) 24 volts
c) 3 volts
A
b) 24 volts
213
Q
- Of the following which pair of materials would most readily become magnetized?
a) copper and steel
b) nickel and bronze
c) iron and steel
A
c) iron and steel
214
Q
- The formula for resistance in series is
a) RT = R1 + R2 + R3…RN
b) RT = R1 x R2 x R3…RN
c) 1/RT = 1/ (R1 x R2 x R3 …RN)
A
a) RT = R1 + R2 + R3…RN
215
Q
- The core material used for an electromagnet is soft iron because
a) it demagnetizes easily
b) its magnetism is not easily destroyed
c) it retains most of its flux density when demagnetized
A
a) it demagnetizes easily
216
Q
- What is the combined value of resistances of 4 ohm and 6 ohm connected in parallel?
a) 24 ohm
b) 2.4 ohm
c) 0.24 ohm
A
b) 2.4 ohm
217
Q
- Permanent magnets in an AC generator are
a) to provide initial excitation
b) to control the frequency
c) to rectify the current
A
a) to provide initial excitation
218
Q
- The method of ascertaining the voltage of a standard aircraft lead-acid battery is by checking
a) the voltage off load
b) the voltage on open circuit
c) the voltage with rated load switched ON.
A
c) the voltage with rated load switched ON.
219
Q
- Generator brushes are normally made of
a) carbon
b) brass
c) steel
A
a) carbon
220
Q
- If the voltage across a resistor is doubled
a) the current is doubled
b) the resistance is halved
c) the current is halved
A
a) the current is doubled
221
Q
- As the generator load is increases (within its rated capacity), the voltage will
a) remain constant and the amperage output will decrease
b) decrease and the amperage output will increase
c) remain constant and the amperage output will increase
A
c) remain constant and the amperage output will increase
222
Q
- If a number of resistors are connected in parallel, the total resistance is
a) the same as the lowest
b) smaller than the lowest
c) greater than the lowest
A
b) smaller than the lowest
223
Q
- A charged body is said to have
a) a surplus or deficiency of electrons
b) a surplus of protons
c) a deficiency of neutrons
A
a) a surplus or deficiency of electrons
224
Q
- The ratio between apparent power and true power is the
a) efficiency
b) power rating
c) power factor
A
c) power factor
225
Q
- The voltage output of a generator is controlled by
a) varying the current of the output
b) varying the resistance of the output
c) varying the current of the field
A
c) varying the current of the field
226
Q
- The total current flowing in a circuit of 200 lamps in parallel, each of a resistance of 400 ohm and connected across an input of 100 volts is
a) 50 amps
b) 25 amps
c) 40 amps
A
a) 50 amps
227
Q
- The current flowing in the armature of a DC motor is equal to
a) (applied volts - generated volts) x armature resistance
b) (applied volts + generated volts) / armature resistance
c) (applied volts - generated volts) / armature resistance
A
c) (applied volts - generated volts) / armature resistance
228
Q
- In the circuit shown the 24 volt battery has an internal resistance of 1 ohm and the ammeter indicates a current of 12 amperes. The value of the load resistance is
a) 1 ohm
b) 2 ohms
c) 6 ohms
A
a) 1 ohm
229
Q
- One advantage of using Ac electrical power in aircraft is
a) the greater ease in stepping the voltage up or down
b) AC electrical motors can be reversed while dc motors cannot
c) the effective voltage is 1.41 times the maximum instantaneous voltage; less power input is required
A
a) the greater ease in stepping the voltage up or down
230
Q
- The quill drive on an aircraft generator
a) makes possible the use of roller bearings at the drive end
b) damps out vibrations
c) damps out any commutator ripple
A
b) damps out vibrations
231
Q
- The amount of electricity a capacitor can store is
directly proportional to the
a) distance between the plates and inversely proportional to the plate area
b) plate area and is not affected by the distance between the plates
c) plate area and inversely proportional to the distance between the plates
A
c) plate area and inversely proportional to the distance between the plates
232
Q
- When resistors are in parallel, the total resistance is
a) smaller than the smallest resistor
b) the sum of all the resistors
c) larger than the smallest resistor
A
a) smaller than the smallest resistor
233
Q
- What device is used to convert alternating current, which has been induced into the loops of the rotating armature of a DC generator into direct current as it leaves
the generator?
a) a commutator
b) an inverter
c) a rectifier
A
a) a commutator
234
Q
- Two similar 12v batteries connected in parallel will produce
a) 24V e.m.f. with twice the capacity of each battery
b) 24v e.m.f. with the same capacity as each battery
c) 12V e.m.f. with twice the capacity of each battery
A
c) 12V e.m.f. with twice the capacity of each battery
235
Q
- Unless otherwise specified, any values given for current or voltage in an AC circuit are assumed to be
a) maximum values
b) effective values
c) instantaneous values
A
b) effective values
236
Q
- If a heavy mechanical load is removed from a series
motor
a) the speed will increase and the armature current will decrease
b) the speed will decrease and the armature current will decrease
c) the speed will increase and the armature current will increase
A
a) the speed will increase and the armature current will decrease
237
Q
- In a vector diagram showing the magnitude and direction of the inductance, capacitance and resistance in an AC circuit
a) the inductive reactance would be in opposition tothe capacitive reactance and resistance at 90 degrees
b) the inductive and capacitance reactance would be additive with the resistance subtractive
c) it is impossible to show values of this kind using vectors
A
a) the inductive reactance would be in opposition tothe capacitive reactance and resistance at 90 degrees
238
Q
- If service No. 1 is isolated from the supply busbar shown there will be
a) an increase in supply voltage
b) a decrease in supply voltage
c) a decrease in total current consumption
A
c) a decrease in total current consumption
239
Q
- An increase in operating temperature in most electrical devices carrying current results in
a) an increase in resistance and a decrease in current
b) a decrease in resistance and an increase in current
c) no effect on the resistance and current
A
a) an increase in resistance and a decrease in current
240
Q
- The voltage of a secondary cell is
a) determined by the number of plates
b) determined by the area of the plates
c) determined by the active materials on the plates
A
c) determined by the active materials on the plates
241
Q
- The basis for transformer operation in the use of alternating current is mutual
a) reactance
b) inductance
c) capacitance
A
b) inductance
242
Q
- The exciter winding in a brushless AC generator is supplied with electrical power from
a) permanent magnets
b) the busbar
c) a rotating generator integrally mounted on the same shaft as the AC windings
A
c) a rotating generator integrally mounted on the same shaft as the AC windings
243
Q
- If the cross-sectional area of a conductor is doubled, with voltage constant, the current will
a) halve
b) double
c) remain constant
A
b) double
244
Q
- Eddy currents in a transformer can be reduced by
a) using a special non metallic material
b) using a single solid piece of metal
c) laminations
A
c) laminations
245
Q
- If two resistors of 5 and 10 ohm respectively are connected in series and the current in the 5 ohm resistor is 1A. what is the current in the 10 ohm resistor?
a) 1/3 amp
b) it cannot be found without knowing the applied voltage
c) 1 amp
A
c) 1 amp
246
Q
- The term used to denote the strength of a magnetic field is
a) retentivity
b) hysterisis
c) flux density
A
c) flux density
247
Q
- At resonant frequency the phase difference between the voltage and current of an AC supply feeding an inductive and capacitive network is
a) 0 degrees
b) 180 degrees
c) 90 degrees
A
a) 0 degrees
248
Q
- What is the ratio of turns between the primary coil winding and the secondary coil winding of a transformer designed to triple its input voltage?
a) primary will have three times as many turns as its secondary
b) primary will have twice as many turns as its secondary
c) primary will have one-third as many turns as its secondary
A
c) primary will have one-third as many turns as its
secondary
249
Q
- A direct current of 12 milliamperes flows through a circuit which has a resistance of 1000 ohms. The power dissipated by the circuit is
a) 12 milliwatts
b) 12 watts
c) 144 milliwatts
A
c) 144 milliwatts
250
Q
- The voltage in a series circuit
a) is different in each component
b) is the same in each component
c) is less than it would be in a parallel circuit
A
a) is different in each component
251
Q
- Which aircraft circuit would be most likely to use frequency wild 200V AC?
a) windscreen heating
b) hydraulic pump
c) standby compass
A
a) windscreen heating
252
Q
- Why are the iron cores of most induction coils laminated?
a) To reduce the effects of eddy currents
b) To increase the core permeability
c) To reduce the core reluctance
A
a) To reduce the effects of eddy currents
253
Q
- A 48-volt source is required to furnish 192 watts to a parallel circuit consisting of three resistors of equal value. What is the value of each resistor?
a) 12 ohm
b) 4 ohm
c) 36 ohm
A
c) 36 ohm
254
Q
- If voltage is 100V, resistance is 25 ohms, what is the current?
a) 2500 amperes
b) 4 amperes
c) 0.4 amperes
A
b) 4 amperes
255
Q
- A soft iron core is used in an ELECTRO magnet because
a) it has HIGH permeability and HIGH coercivity
b) it has HIGH permeability and LOW coercivity
c) it has LOW permeability and HIGH coercivity
A
b) it has HIGH permeability and LOW coercivity
256
Q
- The resistance to electrical flow in a wire depends on
a) the diameter, length, material of wire and temperature
b) the material only - copper or aluminum
c) the length and material of the wire only
A
a) the diameter, length, material of wire and temperature
257
Q
- A transformer should always have its
a) secondary open circuit or on load
b) secondary shorted or on load
c) primary shorted or off load
A
a) secondary open circuit or on load
258
Q
- How can the direction of rotation of a DC electric motor be changed?
a) interchange the wires which connect the motor to the external power source
b) reverse the electrical connections to either the field or armature windings
c) rotate the positive brush one commutator segment
A
b) reverse the electrical connections to either the field or armature windings
259
Q
- An AC generator’s frequency will
a) always be constant regardless of the generators
drive speed
b) vary with changes in field strength
c) be proportional to the RPM at which it is driven
A
c) be proportional to the RPM at which it is driven
260
Q
- A short circuit between the supply and earth
a) does not matter if the circuit uses the aircraft earth as a return
b) could be very dangerous as the current drawn will be very high
c) is not dangerous as the current drawn will be low
A
b) could be very dangerous as the current drawn will be very high
261
Q
- When two coils are linked by a common flux, a voltage can be induced in one by a changing current in the other. This process is known as
a) mutual induction
b) the magnetic effect
c) self induction
A
a) mutual induction
262
Q
- A circuit consists of 3 ohm, 5 ohm and 12 ohm resistors in series, the current flowing in the 5 ohm resistor is 10 amps. What is the applied voltage?
a) 100v
b) 10v
c) 200v
A
c) 200v
263
Q
- Copper is an inferior conductor to aluminum when comparing
a) weight for weight
b) load for load
c) CSA with CSA
A
a) weight for weight
264
Q
- In an AC circuit how is the value of true power calculated?
a) By volts multiplied by amps multiplied by power factor
b) By wattmeter readings multiplied by power factor
c) By voltmeter readings multiplied by ammeter readings
A
a) By volts multiplied by amps multiplied by power factor
265
Q
- A frequency wild AC generator is used for
a) instruments and navigation
b) de-icing loads
c) any AC load
A
b) de-icing loads
266
Q
- Which of the following is not one of the purposes of interpoles in a generator?
a) Reduce field strength
b) Overcome armature reaction
c) Reduce arcing at the brushes
A
a) Reduce field strength
267
Q
- Which of the following would be used to calculate transformer turns ratio?
a) primary turns × secondary turns
b) primary turns ÷ secondary turns
c) secondary turns ÷ primary turns
A
c) secondary turns ÷ primary turns
268
Q
- A good electrical insulator is a material which
a) has more protons than electrons
b) has its electrons tightly bound to their parent atoms
c) contains a large number of positive ions
A
b) has its electrons tightly bound to their parent atoms
269
Q
- To reverse the direction of a series motor
a) the direction of the current through the field is reversed
b) a second series field is fitted
c) the direction of the current through the field and the armature is reversed
A
b) a second series field is fitted
270
Q
- How many cycles of AC voltage are produced in a six-pole alternator of the revolving-field type, with each revolution of the rotor?
a) Four
b) Six
c) Three
A
c) Three
271
Q
- The variable frequency output from an AC generator is used for
a) supplying non-inductive loads
b) the AC supply instead of using inverters
c) driving AC operated instruments
A
a) supplying non-inductive loads
272
Q
- The capacitance of a capacitor is dependent upon
a) the type of material separating the plates
b) the rate of change of current in the circuit
c) the charge on it
A
a) the type of material separating the plates
273
Q
- A piece of equipment is rated at 750 watts and the applied voltage is 30 volts. The value of the protection fuse should be
a) 20 amps
b) 30 amps
c) 15 amps
A
b) 30 amps
274
Q
- The current consumed by a DC starter motor will
a) remain relatively constant over the starting speed range
b) increase as the engine speed increases
c) decrease as the engine speed increases
A
c) decrease as the engine speed increases
275
Q
- When different rated capacitors are connected in parallel in a circuit, the total capacitance is
a) equal to the capacitance of the highest rated capacitor
b) less than the capacitance of the lowest rated capacitor
c) equal to the sum of all the capacitances
A
c) equal to the sum of all the capacitances
276
Q
- The voltage in a transformer secondary coil that contains twice as many loops as the primary coil will be
a) less and the amperage greater than in the primary coil
b) greater and the amperage greater than in the primary coil
c) greater and the amperage less than in the primary coil
A
c) greater and the amperage less than in the primary coil
277
Q
- How are generators rated?
a) Impedance at rated voltage
b) Amperes at rated voltage
c) Watts at rated voltage
A
c) Watts at rated voltage
278
Q
- in a single phase AC generator, frequency is determined by
a) the generator speed
b) controlling the current flow through the voltage field windings
c) the number of pairs of poles
A
a) the generator speed
279
Q
- The risk of a fire due to static electricity is overcome
a) by fitting static wicks and insulating all metal components
b) by connecting all metal components by bonding
c) by fitting static wicks and isolating the battery from inflammable gas sources
A
b) by connecting all metal components by bonding
280
Q
- Due to armature reaction in a DC motor
a) the trailing pole tips are magnetically weakened
b) the leading pole tips are magnetically weakened
c) the magnetic flux is restored by moving the MNA towards the GNA
A
a) the trailing pole tips are magnetically weakened
281
Q
- Two resistors are connected in series and have an e.m.f. of V volts across them. If the voltages across the resistances are V1 and V2 then by Kirchhoff’s law
a) V = V1 + V2
b) V2 = V1 + V
c) V1 = V2 + V
A
a) V = V1 + V2
282
Q
- When an electrical supply becomes open-circuit
a) the loss of continuity will prevent its component from functioning
b) the fuse or circuit breaker should isolate the circuit due to the increased current drawn
c) the component will operate normally but will not switch off
A
a) the loss of continuity will prevent its component from functioning
283
Q
- Some electric motors have two sets of field winding wound in opposite directions so that the
a) speed of the motor can be more closely controlled
b) motor can be operated in either direction
c) power output of the motor can be more closely controlled
A
b) motor can be operated in either direction
284
Q
- The amount of electrical power for a given generator weight is
a) determined by the size of the aircraft
b) greater for DC generator
c) greater for AC generator
A
c) greater for AC generator
285
Q
- When resistors are in parallel the total current is equal to
a) the current through one resistor
b) the sum of the currents
c) the reciprocal of all the currents
A
b) the sum of the currents
286
Q
- What is the ampere-hour rating of a storage battery that is designed to deliver 45 amperes for 2.5 hours?
a) 90.0 ampere-hour
b) 112.5 ampere-hour
c) 45.0 ampere-hour
A
b) 112.5 ampere-hour
287
Q
- How much power must a 24-volt generator furnish to a system which contains the following series loads?
5 ohm, 3 ohm and 12 ohm
a) 450 watts
b) 402 watts
c) 28.8 watts
A
c) 28.8 watts
288
Q
- A volt meter is connected
a) in series or parallel
b) in parallel
c) in series
A
b) in parallel
289
Q
- What polarity do interpoles take in a DC motor?
a) The same as the next main pole behind in the direction of rotation
b) Either, provided they lay on the MNA
c) The same as the next main pole ahead in the direction of rotation
A
a) The same as the next main pole behind in the direction of rotation
290
Q
- On a typical AC generator the output is taken
a) direct from the rotor via slip rings
b) direct from the exciter
c) direct from the stator windings
A
c) direct from the stator windings
291
Q
- Since electrical supplies taken from a bus-bar are in parallel, isolating some of the services would
a) reduce the current consumption from the bus-bar
b) increase the current consumption from the busbar
c) not affect the current consumption, it would reduce the voltage
A
a) reduce the current consumption from the bus-bar
292
Q
- One Picofarad is
a) 1 x 1012 farad
b) 1 x 10-6 farad
c) 1 x 10-12 farad
A
c) 1 x 10-12 farad
293
Q
- Which of these will cause the resistance of a conductor to decrease?
a) Decrease the length or the cross-sectional area
b) Decrease the length or increase the cross-sectional area
c) Increase the length or decrease the cross-sectional
area
A
b) Decrease the length or increase the cross-sectional area
294
Q
- The purpose of bonding is to
a) give generated static an easy return path to the generator
b) stop different potentials developing with subsequent fire risks
c) ensure all components have been securely fitted
A
b) stop different potentials developing with subsequent fire risks
295
Q
- The S.I. unit of magnetic flux density is the
a) Weber
b) Henry
c) Tesla
A
c) Tesla
296
Q
- What is the principal advantage of the series-wound dc motor?
a) Low starting torque
b) Suitable for constant speed use
c) High starting torque
A
c) High starting torque
297
Q
- Interpole windings fitted to DC series wound generators are
a) in series with the field
b) in parallel with the armature
c) in series with the armature
A
c) in series with the armature
298
Q
- One of the chief advantages of alternating current is that it can be transmitted at a high voltage with a low power loss; the voltage can then be changed to any desired value of
a) AC by means of transformers
b) DC by means of transformers
c) DC by means of inverters
A
a) AC by means of transformers
299
Q
- An AC generator is producing the required voltage but a higher frequency than that required. To remedy this, the following action must be taken?
a) Decrease the speed of the prime mover, and then decrease the strength of the field
b) Decrease the speed of the prime mover
c) Decrease the speed of the prime mover, and then increase the strength of the field
A
c) Decrease the speed of the prime mover, and then increase the strength of the field
300
Q
- How many amperes will a 28-volt generator be required to supply to a circuit containing five lamps in parallel, three of which have a resistance of 6 ohms each and two of which have a resistance of 5 ohms each?
a) 25.23 amperes
b) 1 ampere
c) 1.11 amperes
A
a) 25.23 amperes
301
Q
- The area of a hysteresis loop is proportional to the
a) energy dissipated in putting the material through a complete cycle of magnetization and demagnetization
b) relative permeability of the material being magnetized
c) energy absorbed in completely demagnetizing the material
A
a) energy dissipated in putting the material through a complete cycle of magnetization and demagnetization
302
Q
- The current flowing through a circuit can be increased to four times its original value by
a) doubling the applied voltage and halving the resistance
b) halving the applied voltage and halving the resistance
c) doubling the resistance and doubling the applied voltage
A
a) doubling the applied voltage and halving the resistance
303
Q
- When more than two inductors of different inductances are connected in parallel in a circuit, the total inductance is
a) equal to the sum of the individual inductances
b) less than the inductance of the lowest rated inductor
c) equal to the inductance of the highest rated inductor
A
b) less than the inductance of the lowest rated inductor
304
Q
- What polarity do interpoles take in a DC generator?
a) the same as the next main pole ahead in the direction of rotation
b) the same as the next main pole behind in the direction of rotation
c) either, providing they lay on M.N.A.
A
a) the same as the next main pole ahead in the direction of rotation
305
Q
- What happens to the resistance of a copper conductor when the temperature increases?
a) It increases
b) It decreases
c) It remains the same
A
a) It increases
306
Q
- The method most often used in overcoming the effect of armature reaction is through the use of
a) shaded poles
b) interpoles
c) drum-wound armatures in combination with a negatively connected series field
A
b) interpoles
307
Q
- The core material used for an electromagnet is soft iron because
a) it demagnetizes easily
b) it retains most of its flux density when demagnetized
c)its magnetism is not easily destroyed
A
a) it demagnetizes easily
308
Q
- The switch on a DC circuit containing a fully charged capacitor is opened. The voltage across the capacitor
a) drops immediately to zero
b) starts to fall exponentially to zero
c) remains equal to the original charging voltage supply
A
c) remains equal to the original charging voltage supply
309
Q
- in a 3 phase generator with balanced load, the potential between the neutral point and earth is
a) equal to line volts
b) equal to phase volts
c) zero volts
A
c) zero volts
310
Q
- A direct current of 12 milliamperes flows through a circuit which has a resistance of 1000 ohms. The power dissipated by the circuit is
a) 12 milliwatts
b) 12 watts
c) 144 milliwatts
A
c) 144 milliwatts
311
Q
- An increase in which of the following factors will cause an increase in the inductive reactance of a circuit?
a) Resistance and capacitive reactance
b) Resistance and voltage
c) Inductance and frequency
A
c) Inductance and frequency
312
Q
- in transformer operation, hysteresis losses are
a) current overcoming coil resistance
b) induced current in the iron core
c) energy wasted in reversing core magnetization
A
c) energy wasted in reversing core magnetization
313
Q
- The starting current of a series-wound DC motor, in passing through both the field and armature windings produces a
a) low starting torque
b) speed slightly higher when unloaded
c) high starting torque
A
c) high starting torque
314
Q
- A non-magnetic metal
a) has no permeability
b) has high retentivity
c) is a poor conductor
A
a) has no permeability
315
Q
- The power output of an AC parallel generator system is measured in
a) KVA
b) KW / KVARS
c) amperes
A
b) KW / KVARS
316
Q
- The shape of the output waveform of an AC generator is known as a
a) sine wave
b) cosine wave
c) frequency wave
A
a) sine wave
317
Q
- in a circuit containing three resistors of equal value connected in series and one of the resistors short circuits, the effect is for the current in the other two resistors to
a) increase
b) remain the same
c) decrease
A
a) increase
318
Q
- To increase the speed of a shunt motor a resistance is placed
a) in series with the armature
b) in parallel with the field
c) in series with the field
A
c) in series with the field
319
Q
- Frequency (Hz) is the number of cycles per
a) revolution
b) minute
c) second
A
c) second
320
Q
- In a series resistive circuit
a) the total voltage equals the difference between the individual voltages
b) the total voltage is equal to the sum of the individual voltages
c) the total voltage is the same as the highest individual
A
b) the total voltage is equal to the sum of the individual voltages
321
Q
- The current in a DC circuit containing a fully charged capacitor is
a) zero
b) is dependent upon the size of the capacitance of the capacitor
c) maximum
A
a) zero
322
Q
- The sum of the instantaneous E.M.F.’s in a three phase system is
a) equal to the line voltage
b) three times the phase voltage
c) zero
A
c) zero
323
Q
- A capacitor is a barrier to
a) both
b) A.C
c) D.C
A
c) D.C
324
Q
- One revolution of a three phase generator will
produce
a) 3 cycles
b) 2 cycles
c) 1 cycle
A
c) 1 cycle
325
Q
- If the North pole of a magnet is brought nearer to the North pole of another magnet
a) attraction between them will be increased
b) repulsion between them will be increased
c) repulsion between them will be reduced
A
b) repulsion between them will be increased
326
Q
- A 200 volt motor is taking 10 amperes armature current, the armature resistance is 0.1 ohm. The B.EMF under these conditions will be
a) 201 volts
b) 199 volts
c) 1 volt
A
b) 199 volts
327
Q
- What is the effect of inserting an iron core into a current carrying coil?
a) The flux density of the original magnetic field produced by the coil is increased
b) The flux density of the original magnetic field remains constant
c) The core tends to move from a stronger to a weaker part of the field
A
a) The flux density of the original magnetic field produced by the coil is increased
328
Q
- What is the total capacitance of a parallel circuit containing three capacitors with capacitance of 0.25microfarad, 0.03microfarad, and 0.12microfarad, respectively?
a) 0.04 µF
b) 0.04 pF
c) 0.4 µF
A
c) 0.4 µF
329
Q
- At resonant frequency the phase difference between the voltage and current of an AC supply feeding an inductive and capacitive network is
a) 0 degrees
b) 180 degrees
c) 90 degrees
A
a) 0 degrees
330
Q
- The frequency of a power wave in an AC resistance circuit is
a) the same as the frequency for voltage and current
b) half the frequency for voltage and current
c) twice the frequency for voltage and current
A
c) twice the frequency for voltage and current
331
Q
- The reading on the ammeter in the circuit shown is
a) 3A
b) 6A
c) 12A
A
b) 6A
332
Q
- The ‘A’ phase of a three phase power system is colour coded
a) blue
b) yellow
c) red
A
c) red
333
Q
- The total resistance of the circuit shown is
a) 12 Ohms
b) 3 Ohms
c) 7.5 Ohms
A
b) 3 Ohms
334
Q
- What is a method used for restoring generator field residual magnetism?
a) Flash the fields
b) Reseat the brushes
c) Energize the armature
A
a) Flash the fields
335
Q
- A 1µF capacitor is equivalent to
a) 0.000,001 Farads
b) 1,000,000 Farads
c) 0.001 Farads
A
a) 0.000,001 Farads
336
Q
- The opposition offered by a coil to the flow of alternating current is called (disregard resistance)
a) impedance
b) reluctance
c) inductive reactance
A
c) inductive reactance
337
Q
- A high surge of current is required when a DC electric motor is first started. As the speed of the motor increase
a) the applied emf increases proportionally
b) the counter emf decreases proportionally
c) the counter emf builds up and opposes the applied emf, thus reducing the current flow through the armature
A
c) the counter emf builds up and opposes the applied emf, thus reducing the current flow through the armature
338
Q
- The tolerance of the AC generator frequency is
a) 40 Hz
b) 10 Hz
c) 20 Hz
A
b) 10 Hz
339
Q
- The various parts of an aircraft airframe are maintained at the same potential by
a) the supply bus-bars
b) static discharge wicks
c) bonding
A
c) bonding
340
Q
- When two capacitors are connected in series
a) the charge stored on each is directly proportional to its capacitance
b) the charge stored on each is the same
c) the charge stored on each is inversely proportional to the voltage across it
A
b) the charge stored on each is the same
341
Q
- Aircraft generators are cooled by
a) oil cooling radiators around the main body
b) fuel cooling radiators
c) ram air
A
c) ram air
342
Q
- The voltage of an AC generator
a) rises to max in one direction, falls to zero and rises in the same direction
b) rises to max in one direction then falls to zero then rises to max in the opposite direction
c) rises to max in one direction and remains
A
b) rises to max in one direction then falls to zero then rises to max in the opposite direction
343
Q
- The charge on a capacitor is expressed as
a) the ratio Q/V
b) the product Q x V
c) the product C x V
A
c) the product C x V
344
Q
- A shunt is used with
a) an ammeter
b) an ohmmeter
c) a voltmeter
A
a) an ammeter
345
Q
- The resistance of the current return path through the aircraft is always considered negligible, provided the
a) generator is properly grounded
b) voltage drop across the circuit is checked
c) structure is adequately bonded
A
c) structure is adequately bonded
346
Q
- An ammeter is connected into a circuit in
a) parallel
b) shunt
c) series
A
c) series
347
Q
- When handling a high voltage capacitor in an electrical circuit, be sure it
a) has a full charge before removing it from the circuit
b) is fully discharged before removing it from the circuit
c) has at least a residual charge before removing it from the circuit
A
b) is fully discharged before removing it from the circuit
348
Q
- When a circuit with a series inductance and capacitance is at resonant frequency
a) the current in the circuit decreases
b) the impedance of the circuit is such that the voltage is in phase with the current
c) the impedance of the circuit is such that the voltage leads the current by exactly 90 degrees
A
b) the impedance of the circuit is such that the voltage is in phase with the current
349
Q
- in an AC circuit, the effective voltage is
a) equal to the maximum instantaneous voltage
b) greater than the maximum instantaneous voltage
c) less than the maximum instantaneous voltage
A
c) less than the maximum instantaneous voltage
350
Q
- On a combined DC starter - generator system
a) the voltage regulator is connected to the shunt field after the start cycle is completed
b) the series coil is open circuit during the engine start sequence
c) the voltage regulator controls the start sequence during engine starting
A
a) the voltage regulator is connected to the shunt field after the start cycle is completed
351
Q
- A pure capacitor, inductor and resistor are connected in series and the voltage drops across each are 10V and the total current flowing in the circuit is 1A.
How much true power is the circuit consuming?
a) 30VA
b) 30W
c) 10W
A
c) 10W
352
Q
- If a capacitor 1µF and an inductor 10mH are connected in parallel what is their approximate resonant frequency?
a) 62Hz
b) 3.2MHz
c) 1.6kHz
A
c) 1.6kHz
353
Q
- Which wave form is stepped positive and negative with unequal length sides?
a) Trapezoidal wave
b) Rectangular wave
c) Saw tooth wave
A
a) Trapezoidal wave
354
Q
- The value of an AC sine wave that will give an equivalent heating effect in a DC resistor is the
a) average value
b) RMS value
c) peak value
A
b) RMS value
355
Q
- Where is the magnetic dip least?
a) Poles
b) Equator
c) Isoclinals
A
b) Equator
356
Q
- The dielectric constant of a capacitor is a measurement of
a) the electrostatic energy storing capacity of the capacitor dielectric
b) the electrical resistance of the capacitor dielectric
c) the electrical repulsion of electrons within the dielectric material
A
a) the electrostatic energy storing capacity of the capacitor dielectric
357
Q
- To reverse the direction of rotation on a DC shunt motor, you must change the direction of the current through
a) the field windings or the armature windings
b) the armature windings only
c) the field windings and the armature windings
A
a) the field windings or the armature windings
358
Q
- If the field current to a shunt wound DC motor is decreased when operating at a constant load, the motor speed will
a) reduce
b) increase
c) not change
A
b) increase
359
Q
- An electric current is
a) a surplus of free electron
b) an excitement of electrons in a metal
c) an ordered flow of electrons
A
c) an ordered flow of electrons
360
Q
- An atom contains
a) molecules
b) hydrogen
c) electrons
A
c) electrons
361
Q
- What causes a transformer to be noisy?
a) High coil resistance
b) An air gap in the core
c) High core losses
A
b) An air gap in the core
362
Q
- Carbon has a
a) negative temperature coefficient
b) positive temperature coefficient
c) temperature coefficient of zero
A
a) negative temperature coefficient
363
Q
- The peak factor for a sine wave is
a) 0.707
b) 1.414
c) 1.11
A
b) 1.414
364
Q
- If a motor is spinning at 50 cycles per second, how long is 1 cycle?
a) 0.02 seconds
b) 50 seconds
c) 0.83 seconds
A
a) 0.02 seconds
365
Q
- An integrated step input at unequal time base produces
a) a square wave
b) a sine wave
c) a saw tooth wave
A
c) a saw tooth wave
366
Q
- A capacitor in series and inductor in parallel make what kind of filter?
a) Band pass
b) High pass
c) Low pass
A
b) High pass
367
Q
- If a load in series has a current passing through it, the magnetic field can be worked out by using
a) the corkscrew rule
b) left hand rule
c) right hand rule
A
a) the corkscrew rule
368
Q
- If the current flowing into a junction is 5A, 3A, 4A in and 10A out. What is the 5th wire carrying?
a) 2A in
b) 2A out
c) 5A out
A
b) 2A out
369
Q
- If an insulated conductor is placed near to a negatively charged rod, the nearest end of the conductor becomes
a) negatively charged
b) positively charged
c) No change will occur
A
b) positively charged
370
Q
- If 2 resistors, one red, yellow, black, gold and the other violet, blue, black, silver were replaced by a single resistor. Ignoring tolerance, what would the color coding
be?
a) Brown, black, brown
b) Brown, black, black
c) Black, brown, blac
A
a) Brown, black, brown
371
Q
- Germanium and silicon have how many electrons in their outer shell
a) 4
b) 2
c) 6
A
a) 4
