b2 module 3 test 1

MODULE 03 PRACTICE MCQ PART 01

http://www.aircrafttechtrng.com

An # represents the correct answer

1. 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

2. 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

3. 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

4. Magnetic inclination is the least at the

a) poles

# b) equator

c) isoclines



5. Ferromagnetic materials can be magnetized

a) within a band of temperatures

b) above a certain temperature

# c) below a certain temperature

6. 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

7. 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

8. 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



9. What is the phase difference in a circuit with 100V, drawing 0.5 amps, consuming 50

Watts?

a) 45

b) 90

# c) 0

10. 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

11. 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

12. A Transformer has 4500 secondary turns and 750 primary turns. Its turns ratio is

a) 1:6

# b) 6:1

c) 1/6



13. 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

14. 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

15. If you apply this waveform to this circuit, what is the output across the capacitor?

a) Zero

b) Pulsed negative

# c) Pulsed positive

16. What value is the same as the equivalent D.C. heating effect?

# a) Root Mean Square

b) Average

c) Peak



17. 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

18. What shape is the waveform when the input pulse and the time base are unequal?

a) Square

# b) Rectangular

c) Saw tooth

19. A sine wave has 5 amps RMS value. What is the peak value?

a) 6.37 amps

# b) 7.07 amps

c) 10 amps

20. In this circuit

# a) current leads voltage

b) current lags voltage

c) current = voltage



21. 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

22. Power factor relates to

# a) true power and apparent power

b) KW and KVAR

c) horsepower and Watts

23. 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

24. If current lags voltage by 90, the circuit is

a) capacitive

b) resistive

# c) inductive



25. 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

26. A three-phase motor has the windings

# a) 120 apart

b) 90 apart

c) 180apart

27. 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

28. 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



29. 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

30. 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

31. 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

32. What does the following circuit represent?

a) Integrator

b) Low pass filter

# c) Differentiator



33. What charge does the nucleus of an atom possess?

# a) Positive

b) Negative

c) Neutral

34. What is the maximum number of electrons in shell N of an atom?

a) 16

# b) 32

c) 18

35. 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

36. 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



37. A 10V battery supplies a resistive load of 10 ohms for 1 minute. What is the work done?

a) 60J

b) 10J

# c) 600J

38. 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

39. 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

40. 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



41. Glass is an example of a

a) paramagnetic material

# b) diamagnetic material

c) coercive material

42. Which of the following is absolute permeability?

# a)

b) o

c) r

43. 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

44. 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.



45. 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

46. 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

47. 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

48. 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



49. If the phase voltage in a star connected generator is 200V what will be the line voltage?

a) 115V

b) 200V

# c) 346V

50. 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

51. 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

52. 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



53. 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

54. A capacitor in a single phase AC motor is to

a) prevent spikes

b) block DC

# c) provide a phase shift

55. The slip speed of an induction motor is

# a) stator speed - rotor speed

b) stator speed + rotor speed

c) stator speed

rotor speed

56. The primary winding of a 3-phase transformer

a) is delta wound

b) is star wound

# c) could be either delta or star wound



57. The symbol for flux density is

a) H

# b) B

c)

58. A galvanometer measures

a) millivolts

b) megohms

# c) milliamps

59. A battery rated at 40 Ah will supply 200 mA for

# a) 200 hours

b) 5 hours

c) 20 hours

60. The unknown resistance R in the wheatstone bridge shown is

a) 1 ohm

# b) 4 ohms

c) 16 ohms



61. Which of the following materials is easiest to magnetize?

# a) Soft iron

b) High grade steel

c) Cast iron

62. AC generators are rated in

a) kVARs

b) kW

# c) kVA

63. 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

64. 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



65. In a transformer, if the rate of change of current increases, the mutual inductance will

a) increase

b) decrease

# c) remain the same

66. 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

67. 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

68. What is the wave shape of the x-axis input of a traversing oscilloscope image?

a) square

b) rectangular

# c) triangular



69. An inductance/resistance motor is

a) better than a capacitance motor

b) restricted to low loads only

# c) less efficient than a capacitance motor

70. The voltage at point A is

# a) 7 V

b) 21 V

c) 28 V

71. 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

72. 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



73. 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

74. 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

75. 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

76. If electrons are added to an atom it becomes

a) a positive ion

# b) a negative ion

c) a neutral ion



77. An element whose atoms have fewer than 4 electrons in their valency shell are

# a) good conductors

b) good insulators

c) semiconductors

78. In a purely resistive AC circuit, the current vector is

# a) in phase with the voltage vector

b) +90o out of phase with the voltage vector

c) -90o out of phase with the voltage vector

79. 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

80. 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



81. An electrolytic capacitor is used where

a) minimum losses are essential

# b) there is a polarized input

c) high frequency AC is used

82. If a connection to an AC motor is disconnected, the motor will

a) slow down and stop

# b) continue to run

c) stop

83. 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

84. This is a diagram of a

a) band pass filter

b) high pass filter

# c) low pass filter



85. 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

86. A parallel circuit at resonance has

# a) maximum impedance

b) minimum impedance

c) zero impedance

87. 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

88. 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



89. 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

90. The time required to fully charge a 1 F capacitor in series with a 100k ohm resistor is

# a) 100 ms

b) 1 s

c) 100 s

91. 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

92. This is a symbol for

# a) a voltage dependant resistor

b) a variable differential resistor

c) a visual display rectifier



93. If a generator speed is halved and the field strength is doubled, the voltage output will be

a) halved

b) doubled

# c) unchanged

94. Point A on the armature of the generator shown is producing

# a) maximum current

b) minimum current

c) zero current

95. An accumulation of hydrogen on the plates of a battery is known as

a) hydration

# b) polarization

c) ionization

96. 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



97. Which of the following is 1 Amp?

# a) 1000 mA

b) 1000 A

c) 1000 kA

98. A paramagnetic material has a relative permeability of

# a) greater than unity

b) less than unity

c) zero

99. What part of a battery is covered in hydrogen during polarization?

a) Cathode

# b) Anode

c) Both the anode and the cathode

100. Electricity conducts through

a) solids only

# b) solids and liquids

c) vacuum



101. The term that describes the combined resistive forces in an AC circuit is

# a) impedance

b) resistance

c) total resistance

102. 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

103. An example of a good electrical insulator is

# a) glass

b) aluminium

c) mercury

104. 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



105. An accumulation of hydrogen on the plates of a battery is known as

a) hydration

# b) polarization

c) ionization

106. 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

107. 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

108. 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



109. 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

110. 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

111. The quill drive on an aircraft generator

a) makes possible the use of roller

b) damps out any commutator ripple

# c) damps out vibrations

112. 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



113. 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

114. 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

115. 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

116. Power is the rate of doing work. It is measured in

# a) joules/second

b) watts/second

c) joules x seconds



117. 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

118. 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

119. 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

120. Through which material will magnetic lines of force pass the most readily?

a) aluminium

# b) iron

c) copper



121. Electricity conducts through

a) solids only

# b) solids and liquids

c) vacuum

122. The secondary coil of a transformer has 1500 turns and 10 resistance. The primary coil has 1 k resistance. How many turns does the primary coil have?

# a) 15,000

b) 150,000

c) 1,500,000

123. 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

124. In a star wound primary transformer, how could you wind the secondary winding?

a) star only

b) delta only

# c) either delta or star



125. 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

126. 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

127. A 50 F 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

128. The total resistance of the circuit shown is

a) 1.33 Ohms

b) 12 Ohms

# c) 3 Ohms



129. A step up transformer has

a) one winding

# b) two windings

c) three windings

130. 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

131. E.M.F. in an electric circuit corresponds to what in a magnetic circuit

# a) mmf

b) flux

c) reluctance

132. Time constant of an inductor is

a) LR

# b) L/R

c) L2/R



133. Permanent magnets have

a) high reluctance, low coercive force

b) low reluctance, high coercive force

# c) high reluctance, high coercive force

134. 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

135. 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

136. 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



137. 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

138. 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

139. The power in a circuit when voltage and resistance is given can be found by

a) VxR

# b) VxV / R

c) VxVxR

140. A piezoelectric device generates electricity through

# a) pressure

b) friction

c) light



141. 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

142. Potentiometers are used as a

# a) variable voltage source

b) variable resistor

c) variable current source

143. 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

144. Calculate the speed of a 400 Hz, 4 pole machine

# a) 12,000 rpm

b) 6000 rpm

c) 8000 rpm



145. 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

146. Linear actuators used in aircraft are of

# a) split field series wound type.

b) split field shunt wound type

c) compound wound type

147. 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

148. The charge on a proton is

a) neutral

# b) positive

c) negative



149. in conventional current flow, what is Fleming's right hand rule used for

a) Motors

# b) Generators

c) Inductors

150. In a capacitive circuit, if the frequency is increased

# a) the current increases

b) impedance increases

c) reactance remains the same

151. Three 12 F capacitors are in series. The total capacitance is

a) 12 F

# b) 4 F

c) 36 F

152. A 500 ohm resistor carries a 3 amp current. What is the power dissipated?

a) 5 kW

# b) 4.5 kW

c) 500 W



153. A paramagnetic material has a relative permeability

a) less than unity

# b) greater than unity

c) equal to unity

154. 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

155. 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

156. 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



157. A potentiometer has which of the following properties?

# a) 3 terminals

b) preset values

c) wire wound

158. A 3 ohm resistor dissipates 27 Watts. How much current flows through it?

# a) 3 A

b) 9 A

c) 0.15 A

159. in a 2 phase generator, how far apart are the windings electrically?

a) 45o

# b) 90o

c) 180o

160. The SI unit of work is

a) Joules per second (Watts)

# b) Kilogram metres - force

c) Joules per metre



161. in the circuit below, what happens to the total circuit impedance if L is tripled?

# a) Increases

b) Remains the same

c) Reduces

162. in a voltaic cell, what is the build-up on the cathode called?

a) Polarization

# b) Sulphation

c) Hydration

163. A sine wave has a periodic time of 0.5 milliseconds. What is the frequency

a) 200 Hz

# b) 2 kHz

c) 20 kHz

164. 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



165. Where are the output windings on an AC generator?

# a) Stator

b) Rotor with slip rings

c) Rotor with commutator

166. 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

167. If the rate of change of current is halved, mutual inductance will

a) double

# b) stay the same

c) halve

168. 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



169. 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

170. in a tuned circuit at resonance, the circuit will be

a) inductive

# b) resistive

c) capacitive

171. The time constant for an inductor is

# a) L/R

b) R/L

c) L x R

172. 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



173. 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

174. 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

175. The earth's magnetic field is greatest at the

# a) magnetic poles

b) geographic poles

c) magnetic equator

176. If a 1 ohm circuit produces a 50 W output, the phase angle is

# a) 0o

b) 90o

c) 45o



177. 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

178. 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

179. 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

180. A coulomb is

a) one ampere per second

# b) one ampere x second

c) one second per ampere



181. 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

182. 20 amperes flow for 20 seconds. How many coulombs has flowed?

# a) 400

b) 20

c) 1

183. 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

184. 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



185. 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

186. 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

187. A volt can be considered to be a

# a) unit of electrical pressure

b) quantity of electrical energy

c) unit of electrical power

188. If the resistance of an electrical circuit is increased

a) the voltage will increase

b) the current will increase

# c) the current will decrease



189. If 2 coulombs flowed through a circuit in 2 seconds, the circuit would have

a) 2 volts PD

b) 2 amps

# c) 1 amp

190. 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

191. Doubling the running time of an electrical machine would

# a) double the joules used

b) double the watts used

c) double the current used

192. What is 3.25 volts in millivolts

a) 3.25 millivolts

# b) 3,250 millivolts

c) 325,000 millivolts



193. Electromotive force is measured in

a) Watts

b) Ohms

# c) Volts

194. Six resistors each of 6 ohms would be

a) 36 ohms in parallel

b) 1 ohm in series

# c) 1 ohm in parallel

195. A capacitor in a single phase motor is to

# a) provide a phase shift

b) prevent sparking at the switch

c) provide smoothing

196. The mass of an atom is contained mainly in the

a) electron

# b) nucleus

c) proton



197. 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

198. 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

199. 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

200. The lines of magnetic flux from a magnet will

# a) repel each other

b) attract each other

c) have no effect upon each other



201. A photozoidal cell produces electricity when subjected to

# a) light

b) heat

c) pressure

202. A thermocouple indicator is basically a type of

a) milliammeter

# b) millivoltmeter

c) milliohmeter

203. 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

204. A potentiometer varies

# a) voltage

b) current

c) resistance



205. Starter motors are usually

# a) series wound

b) compound wound

c) shunt wound

206. 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

207. 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

208. What does a rectifier do?

a) Changes direct current into alternating current

# b) Changes alternating current into direct current

c) Reduces voltage



209. Two 12V 40 amp hour batteries connected in parallel will produce

a) 24V 80 ah

# b) 12V 80 ah

c) 24V 40 ah

210. When an atom loses or gains an electron it is called

a) a current

# b) an ion

c) a molecule

211. 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

212. 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



213. Of the following which pair of materials would most readily become magnetized?

a) copper and steel

b) nickel and bronze

# c) iron and steel

214. 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)

215. 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

216. 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



217. Permanent magnets in an AC generator are

# a) to provide initial excitation

b) to control the frequency

c) to rectify the current

218. 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.

219. Generator brushes are normally made of

# a) carbon

b) brass

c) steel

220. If the voltage across a resistor is doubled

# a) the current is doubled

b) the resistance is halved

c) the current is halved



221. 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

222. 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

223. A charged body is said to have

# a) a surplus or deficiency of electrons

b) a surplus of protons

c) a deficiency of neutrons

224. The ratio between apparent power and true power is the

a) efficiency

b) power rating

# c) power factor



225. 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

226. 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

227. 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

228. 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



229. 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; therefore, less

power input is required

230. 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

231. 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

232. 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



233. 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

234. 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

235. 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

236. 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



237. 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 to the 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

238. 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

239. 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

240. 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



241. The basis for transformer operation in the use of alternating current is mutual

a) reactance

# b) inductance

c) capacitance

242. 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

243. If the cross-sectional area of a conductor is doubled, with voltage constant, the current

will

a) halve

# b) double

c) remain constant

244. 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



245. 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

246. The term used to denote the strength of a magnetic field is

a) retentivity

b) hysterisis

# c) flux density

247. 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

248. 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



249. 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

250. 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

251. Which aircraft circuit would be most likely to use frequency wild 200V AC?

# a) windscreen heating

b) hydraulic pump

c) standby compass

252. 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



253. 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

254. If voltage is 100V, resistance is 25 ohms, what is the current?

a) 2500 amperes

# b) 4 amperes

c) 0.4 amperes

255. 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

256. 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



257. 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

258. 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

259. 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

260. 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



261. 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

262. 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

263. Copper is an inferior conductor to aluminum when comparing

# a) weight for weight

b) load for load

c) CSA with CSA

264. 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



265. A frequency wild AC generator is used for

a) instruments and navigation

# b) de-icing loads

c) any AC load

266. 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

267. 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

268. 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



269. 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

270. 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

271. 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

272. The capacitance of a capacitor is dependant upon

# a) the type of material separating the plates

b) the rate of change of current in the circuit

c) the charge on it



273. 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

274. 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

275. 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

276. 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



277. How are generators rated?

a) Impedance at rated voltage

b) Amperes at rated voltage

# c) Watts at rated voltage

278. 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

279. 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

280. 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



281. 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

282. 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

283. 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

284. 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



285. 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

286. 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

287. 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

288. A volt meter is connected

a) in series or parallel

# b) in parallel

c) in series



289. 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

290. 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

291. 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 bus-bar

c) not affect the current consumption, it would reduce the voltage

292. One Picofarad is

a) 1 x 1012 farad

b) 1 x 10-6 farad

# c) 1 x 10-12 farad



293. 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

294. 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

295. The S.I. unit of magnetic flux density is the

a) Weber

b) Henry

# c) Tesla

296. 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



297. 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

Page 37 Mod 3

298. 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

299. 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

300. 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



301. 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

302. 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

303. 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

304. 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.



305. What happens to the resistance of a copper conductor when the temperature increases?

# a) It increases

b) It decreases

c) It remains the same

306. 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

307. 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

308. 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



309. 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

310. 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

311. 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

312. 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



313. 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

314. A non-magnetic metal

# a) has no permeability

b) has high retentivity

c) is a poor conductor

315. The power output of an AC parallel generator system is measured in

# a) KVA

b) KW / KVARS

c) amperes

316. The shape of the output waveform of an AC generator is known as a

# a) sine wave

b) cosine wave

c) frequency wave



317. 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

318. 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

319. Frequency (Hz) is the number of cycles per

a) revolution

b) minute

# c) second

320. 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



321. 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

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