Module 3 – Electrical Fundamentals Sample Questions
Module 3 Electrical Fundamentals 1. A ca capa paci cito torr is full fullyy cha charg rged ed afte afterr 25 se seco cond ndss to a bat batte tery ry vol volta tage ge of 20 20 Volts. Volts. The battery is replaced with a short circuit. What will be the voltage across the capacitor after one time constant a! 12 12." ."## vo voltltss b! $.%" .%" vol volts ts c! 0 volts 2.
The vo volta ltage ra rating of a capacitor is is a! the ma ma&& voltage voltage that that can can be consta constantly ntly applied applied b! the min min voltag voltagee re'uir re'uired ed to charg chargee c! the normal normal ope operat rating ing vo volta ltage ge
%.
The The rel relat ativ ivee pper ermi mitt ttiv ivitityy of of a ca cappac acititor or is a! the relative relative permittiv permittivity ity of the dielectri dielectricc in relation relation to a vacuum vacuum b! the pe permittiv rmittivity ity of dielec dielectric tric in relation relation to dry dry air c! the perm permitti ittivit vityy of th thee dielec dielectri tricc
#.
(ag agnnetic etic inc nclilinnatio ationn iiss the the leas leastt aatt the the a! poles b! e'uator c! isoc isocliline ness
5.
)err )errom omag agne netiticc m maateri terial alss ca can be be mag magne netiti**ed a! within within a ban bandd of temp tempera eratur tures es b! abo above ve a cert certain ain tem temper peratu ature re c! below below a certai certainn tempe temperat rature ure
".
)aradays +aw ,tates that a! the magnitude magnitude of the the -() is directly directly proportio proportional nal to the rate rate of change change of flu& b! the magnitud magnitudee of the -() -() is indirectly indirectly propor proportiona tionall to the rate rate of change of flu& c! the magnitude magnitude of the the -() is directly directly proportio proportional nal to the magnetic magnetic flu& flu&
$.
To redu reduce ce ed eddy dy cu curr rren ents ts in a tra trans nsfo form rmer er you wou ould ld a! reduce reduce the thicnes thicnesss of laminatio laminations ns in the magne magnetic tic core core b! increase increase the thicness thicness of of laminations laminations in in the magnetic magnetic core core c! reduce reduce the number number of turns on the the primary primary winding winding
/. A trans transfo form rmer er ha hass aann inp input ut of #00 #00V V and and a rat ratio io of 21. 21. f the the tran transf sfor orme mer r is delta star wound3 what will the line voltage output be a! 115V b! 200V c! %#"V
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Module 3 – Electrical Fundamentals Sample Questions
4. What What is the the ph phas asee dif diffe fere renc ncee in a circ circui uitt wit withh 100V 100V33 dra drawi wing ng 0.5 0.5 amp amps3 s3 consuming 50 Watts a! #5 b! 40 c! 0 10.. 10 a! b! c!
n an an A.6 A.6 cir circu cuitit33 what what happ happen enss if fre fre'u 'uen ency cy is is redu reduce ced d 6apacitiv 6apacitivee eelemen lements ts may may be be ddamag amaged ed nductive nductive elements elements may be damaged damaged Ther Theree will will be be no effe effect ct
11. A Trans Transfor former mer with with 11 115v prima primary ry volt voltage age and a ratio ratio ooff 51 is supp supplyi lying ng a landing light 7load 2#v #5 amps! is used3 what is the current drawn a! 205 amp ampss b! 4 amps c! #.5 amps 12. A Trans Transfor former mer has #50 #5000 secon secondary dary turns turns and and $50 $50 prim primary ary turns. turns. ts turns ratio is a! 1" b! "1 c! 1" 1%. Two Two induct inductive ive coils coils are are plac placed ed in in close close pro&im pro&imity ity with with each each oth other er at at 40 degrees. The number of flu& linages is a! 0 b! ma ma&i &imu mum m pos posititiv ivee c! ma ma&i &imu mum m ne nega gatitive ve 1# .
A high igh pass fil filter will a! allow fre'u fre'uencie enciess above above a certain certain value to pas passs b! allow fre'u fre'uencie enciess below below a certain certain value value to pass c! allow fre'uencie fre'uenciess within within a range range to to pa pass ss
15. f you you appl applyy this this wave wavefor form m to this this circui circuit3 t3 what what is the the outp output ut acro across ss the the capacitor
a! 8ero b! 9uls 9ulsed ed ne nega gatitive ve c! 9uls 9ulsed ed posi positiv tivee
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Module 3 – Electrical Fundamentals Sample Questions
4. What What is the the ph phas asee dif diffe fere renc ncee in a circ circui uitt wit withh 100V 100V33 dra drawi wing ng 0.5 0.5 amp amps3 s3 consuming 50 Watts a! #5 b! 40 c! 0 10.. 10 a! b! c!
n an an A.6 A.6 cir circu cuitit33 what what happ happen enss if fre fre'u 'uen ency cy is is redu reduce ced d 6apacitiv 6apacitivee eelemen lements ts may may be be ddamag amaged ed nductive nductive elements elements may be damaged damaged Ther Theree will will be be no effe effect ct
11. A Trans Transfor former mer with with 11 115v prima primary ry volt voltage age and a ratio ratio ooff 51 is supp supplyi lying ng a landing light 7load 2#v #5 amps! is used3 what is the current drawn a! 205 amp ampss b! 4 amps c! #.5 amps 12. A Trans Transfor former mer has #50 #5000 secon secondary dary turns turns and and $50 $50 prim primary ary turns. turns. ts turns ratio is a! 1" b! "1 c! 1" 1%. Two Two induct inductive ive coils coils are are plac placed ed in in close close pro&im pro&imity ity with with each each oth other er at at 40 degrees. The number of flu& linages is a! 0 b! ma ma&i &imu mum m pos posititiv ivee c! ma ma&i &imu mum m ne nega gatitive ve 1# .
A high igh pass fil filter will a! allow fre'u fre'uencie enciess above above a certain certain value to pas passs b! allow fre'u fre'uencie enciess below below a certain certain value value to pass c! allow fre'uencie fre'uenciess within within a range range to to pa pass ss
15. f you you appl applyy this this wave wavefor form m to this this circui circuit3 t3 what what is the the outp output ut acro across ss the the capacitor
a! 8ero b! 9uls 9ulsed ed ne nega gatitive ve c! 9uls 9ulsed ed posi positiv tivee
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Module 3 – Electrical Fundamentals Sample Questions
1".
What What valu valuee is is the the same same as as the the e'u e'uiva ivalen lentt :.6. :.6. he heatin atingg eff effect ect a! ;oot ;oot (e (ean an ,'ua ,'uare re b! Average c! 9ea
1$. What What is the relati relations onship hip bet betwe ween en the the volt voltage age and the curren currentt in an A.6 A.6 circuit containing resistance < inductance a! 6urren 6urrentt leads leads volt voltage age by by up to to 40 b! 6urren 6urrentt lags lags volta voltage ge by up up to 40 40 c! 6urren 6urrentt lags lags vo volta ltage ge by by 40 40 1/. What What shap shapee is the wavefo waveform rm when when the input input puls pulsee and and the time time base base are une'ual a! ,'uare b! ;ect ;ectan angu gula larr c! ,aw to tooth 14. 14. a! b! c! 20 .
A sine sine wav wavee has has 5 aamp mpss ;(, ;(, valu value. e. Wha Whatt is the the pea pea val value ue ".% ".%$ am amps ps $.0 $.0$ am amps ps 10 amps n this circuit
a! curren currentt leads leads vo volta ltage ge b! cu curre rrent nt lags lags vol volta tage ge c! cu curre rrent nt = vo volta ltage ge 21.. 21
:ecr :ecrea easi sing ng the the fie field ld cu curre rrent nt in a shu shunt nt mot motor or will will a! increase increase speed speed aand nd decrease decrease tor'ue b! increase increase speed speed aand nd increase increase tor'ue tor'ue c! decrea decrease se speed speed and and increa increase se tor'ue tor'ue
22 .
9ower factor rel relates to a! true true power power and and appar apparent ent pow power er b! >W an andd >V >VA; c! ho hors rsep epow ower er and and Watt Wattss
2%.. 2%
n a delta elta?c ?coonn nnec ecte tedd ge gene nera rato torr a! line volts volts = phase phase volts3 volts3 line current current = root % times times phase curren current. t. b! line volts volts = phase phase volts3 volts3 line current current = phase phase current current divided divided by root % c! line voltage voltage = root root % times phase phase voltage3 voltage3 line line current current = phase current current
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Module 3 – Electrical Fundamentals Sample Questions
2#.
f current lags voltage by 403 the circuit is a! capacitive b! resistive c! inductive
25.
n a % phase motor3 if 1 phase is lost3 the motor a! remains at the same speed b! runs at 1 third speed c! runs at 2 thirds speed
2".
A three?phase motor has the windings a! 120 apart b! 40 apart c! 1/0apart
2$. When measuring the phase and line voltages of a generator3 it was found that line and phase voltages were e'ual. The generator is a! delta wound b! star wound. c! either delta or star wound 2/.
To change the direction of a %?phase induction motor you would a! swap two of the stator connections b! swap all of the input connections c! remove one of the input connections
24.
To calculate generator output you need to now the a! armature speed and number of series conductors b! armature speed and number of parallel conductors c! armature speed and field strength
%0. n a shunt motor3 if you reverse both field current and armature current3 the motor will a! stop b! change direction c! continue to run in the same direction %1.
The permanent magnet in an A.6 generator induces a! A.6. in the e&itor generator b! :.6. in the e&itor generator c! A.6. in the main generator
%2.
What charge does the nucleus of an atom possess a! 9ositive b! @egative c! @eutral
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Module 3 – Electrical Fundamentals Sample Questions
%%.
What does the following circuit represent
a! ntegrator b! +ow pass filter c! :ifferentiator %#.
What is the ma&imum number of electrons in shell @ of an atom a! 1" b! %2 c! 1/
%5. Two 10V3 20 Ah batteries are connected in parallel and connected across a 10?ohm load. ow long could they supply normal current before the voltage begins to decay a! 20 hours b! # hours c! #0 hours %". A 10 V battery supplies a resistive load of 10 ohms for 1 minute. What is the power supplied a! 100 W b! 10 VA c! 10 W %$. A 10V battery supplies a resistive load of 10 ohms for 1 minute. What is the wor done a! "0B b! 10B c! "00B %/. Three capacitors 10 microfarads3 10 nanofarads and 10 millifarads are connected in parallel. What is the total capacitance a! 10.01001m) b! 111m) c! 1.001001m) %4. f a 1m) capacitor has a potential difference across it of 5V what is the energy stored a! 12.5 B b! 12.5 mB c! 25 mB
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Module 3 – Electrical Fundamentals Sample Questions
#0. A capacitor is fully charged after 25 seconds to a battery voltage of 20V. The battery is replaced with a short circuit. What will be the voltage across the capacitor after 1 time constant a! 12."# V b! $.%" V c! 0 V #1.
Class is an e&le of a a! paramagnetic material b! diamagnetic material c! coercive material
#2.
Which of the following is absolute permeability a! D b! Do c! Dr
#%. A solenoid of 10 turns per meter carries a current of 5A. f the current is reduced to 2.5A3 how many turns would be re'uired to maintain the same magnetic field a! 5 b! 50 c! 20 ##.
The point of coercivity occurs when the a! magneti*ing force applied causes the material to become magnetically saturated. b! magnetic flu& is *ero even though a magneti*ing force is being applied. c! magneti*ing force reaches a pea positive or negative value.
#5. What is the mutual inductance if two coils of 10m and 500m have 40E of the flu& transferred from one to the other a! #.5m b! #54m c! "%m #". An inductor has 13000 turns of wire and a cross sectional area of 0.001m2. f the core has a permeability of 0.0003001 and the coil is 0.1m3 what is the value of the inductor a! 10m b! 100micro c! 100m #$. Three inductors 10 m3 5 m and 20 m are connected in parallel. What is the total inductance a! %5 m b! 2./" m c! Without nowing the coupling factor the total inductance cannot be found
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Module 3 – Electrical Fundamentals Sample Questions
#/. f the current reaches a ma&imum through an inductor of 2A in 15 secs3 what is the current after % secs a! 1.2"A b! 0."%A c! 1A #4. f the phase voltage in a star connected generator is 200V what will be the line voltage a! 115V b! 200V c! %#"V 50. A generator is labeled as having 115V200V3 20A and 9) 0./. What is the apparent power in each line that the generator can produce a! 2.%W b! 2.%VA c! #VA 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 Functions are not formed c! the resistance is not increased beyond limits 5%.
An o&ygen molecule is made up of a! two o&ygen atoms sharing electrons b! two o&ygen atoms sharing neutrons c! two o&ygen atoms sharing protons
5#.
A capacitor in a single phase A6 motor is to a! prevent spies b! bloc :6 c! provide a phase shift
55.
The slip speed of an induction motor is a! stator speed ? rotor speed b! stator speed G rotor speed c! stator speed rotor speed
5".
The primary winding of a %?phase transformer a! is delta wound b! is star wound c! could be either delta or star wound
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Module 3 – Electrical Fundamentals Sample Questions
5$.
The symbol for flu& density is a! b! H c! I
5/.
A galvanometer measures a! millivolts b! megohms c! milliamps
54.
A battery rated at #0 Ah will supply 200 mA for a! 200 hours b! 5 hours c! 20 hours
"0.
The unnown resistance ; in the Wheatstone bridge shown is
a! 1 ohm b! # ohms c! 1" ohms "1.
Which of the following materials is easiest to magneti*e a! ,oft iron b! igh grade steel c! 6ast iron
"2.
A6 generators are rated in a! VA;s b! W c! VA
"%.
To find which end of an electromagnet is the @orth 9ole3 use the a! )lemingJs +eft and ;ule b! ;ight and 6lasp ;ule c! 6or ,crew ;ule
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Module 3 – Electrical Fundamentals Sample Questions
"#. have a! b! c!
A capacitor with double the area and double the dielectric thicness will double the capacitance half the capacitance the same capacitance
"5. n a transformer3 if the rate of change of current increases3 the mutual inductance will a! increase b! decrease c! remain the same "". will
f the brae coil on an actuator motor goes open circuit3 the actuator a! over?ride its mechanical stops b! stop c! run slower
"$. The fre'uency of the output of a # pole generator is #00 *. The generator is turning at a! 12000 ;9( b! "000 ;9( c! %000 ;9( "/. What is the wave shape of the &?a&is input of a traversing oscilloscope image a! s'uare b! rectangular c! triangular "4.
$0.
An inductanceresistance motor is a! better than a capacitance motor b! restricted to low loads only c! less efficient than a capacitance motor The voltage at point A is
a! $ V b! 21 V c! 2/ V
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Module 3 – Electrical Fundamentals Sample Questions
$1. A #1 step down transformer draws 115 V and 1 A. The output power will be a! 2/.5 V at # A b! 2/.5 V at 1" A c! #"0 V at 0.25 A $2.
The voltage induced in the stator of an A6 generator is produced by a! a fi&ed magnetic field b! a rotating magnetic field c! an alternating field
$%.
A low fre'uency supply a! may damage inductive components b! will have no effect on inductive components c! will mae the circuit operate faster due to the reduced impedance
$#.
A *inc?carbon battery life depends upon a! the purity of the carbon rod b! the amount of *inc c! the amount of the electrolyte paste
$5. When checing the ,.C. of the electrolyte in a lead acid battery3 you should a! chec all cells because they may be different b! chec only the no. 1 cell because it is the master cell c! chec any cell because they will all be the same $".
f electrons are added to an atom it becomes a! a positive ion b! a negative ion c! a neutral ion
$$. An element whose atoms have fewer than # electrons in their valency shell are a! good conductors b! good insulators c! semiconductors $/.
n a purely resistive A6 circuit3 the current vector is a! in phase with the voltage vector b! G40o out of phase with the voltage vector c! ?40o out of phase with the voltage vector
$4. The 9: at the terminals of an open circuit battery with a small internal resistance will be a! more than the -() b! less than the -() c! the same as the -()
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Module 3 – Electrical Fundamentals Sample Questions
/0. 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 /1.
An electrolytic capacitor is used where a! minimum losses are essential b! there is a polari*ed input c! high fre'uency A6 is used
/2.
f a connection to an A6 motor is disconnected3 the motor will a! slow down and stop b! continue to run c! stop
/%.
A band stop filter a! stops a narrow range of fre'uencies b! stops fre'uencies either side of a narrow range c! attenuates fre'uencies either side of a narrow range
/#.
This is a diagram of a
a! band pass filter b! high pass filter c! low pass filter /5. When comparing the average values of an A6 generator output3 to the pea values a! average voltage = same as the pea voltage b! average voltage = 0."% & pea voltage c! average voltage = 0.$0$ & pea voltage
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Module 3 – Electrical Fundamentals Sample Questions
/".
A parallel circuit at resonance has a! ma&imum impedance b! minimum impedance c! *ero impedance
/$. A resistor dissipates /0 Watts. f it runs for # hours 15 minutes3 how much energy is dissipated in total a! 1.22# (B b! 20.# B c! 141.25 B //. The earth lead of a 2# V e'uipment is 0.5 ohm resistance and carries /0A. ow much power does it dissipate a! %.2 W b! 1.152 W c! 1.42 W /4.
What must you do to mae a % ) capacitor circuit into a 2 ) circuit a! 9ut a 1 ) capacitor in series b! 9ut a 2 ) capacitor in parallel c! 9ut a " ) capacitor in series
40. The time re'uired to fully charge a 1 D) capacitor in series with a 100 ohm resistor is a! 100 ms b! 1 s c! 100 s 41. A 10 ohm resistor has a 1#.1# V pea drop across it. What power is dissipated a! 14.44 W b! 10 W c! 1.#1# W 42.
This is a symbol for
a! a voltage dependant resistor b! a variable differential resistor c! a visual display rectifier 4%. f a generator speed is halved and the field strength is doubled3 the voltage output will be a! halved b! doubled c! unchanged
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Module 3 – Electrical Fundamentals Sample Questions
4#.
9oint A on the armature of the generator shown is producing
a! ma&imum current b! minimum current c! *ero current 45.
An accumulation of hydrogen on the plates of a battery is nown as a! hydration b! polari*ation c! ioni*ation
4".
What is the power dissipated in a 500 ohm resistor with a %A flow a! 1.5 W b! #.5 W c! $50 W
4$.
Which of the following is 1 Amp a! 1000 mA b! 1000 KA c! 1000 A
4/.
A paramagnetic material has a relative permeability of a! greater than unity b! less than unity c! *ero
44.
What part of a battery is covered in hydrogen during polari*ation a! 6athode b! Anode c! Hoth the anode and the cathode
100. a! b! c!
-lectricity conducts through solids only solids and li'uids vacuum
101. is a! b! c!
The term that describes the combined resistive forces in an A6 circuit impedance resistance total resistance
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Module 3 – Electrical Fundamentals Sample Questions
102. ow can the direction of rotation of a :6 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 e&ternal power source c! rotate the positive brush one commutator segment 10%. a! b! c!
An e&le of a good electrical insulator is glass aluminium mercury
10#. 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. a! b! c!
An accumulation of hydrogen on the plates of a battery is nown as hydration polari*ation ioni*ation
10". Which of the following is most liely to cause thermal runaway in a nicel?cadmium battery a! e&cessive 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 10$. -lectric 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 7parallel! c! series 10/. a! b! c!
f a heavy mechanical load is removed from a series motor the speed will decrease and the armature current will decrease the speed will increase and the armature current will decrease the speed will increase and the armature current will increase
104. a! b! c!
,tatic charges remaining in an aircraft are dissipated by the use of a conducting type nose wheel bonding the aircraft to a refuel taner earthing the aircraft as soon as possible
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Module 3 – Electrical Fundamentals Sample Questions
110. a! b! c!
Total resistance in parallel for ;1 and ;2 is 1;T = 7;1 & ;2! L 7;1 G ;2! ;T = 1;1 G 1;2 1;T = 1;1 G 1;2
111. a! b! c!
The 'uill drive on an aircraft generator maes possible the use of roller damps out any commutator ripple damps out vibrations
112. The method of ascertaining the voltage of a standard aircraft lead?acid battery is by checing a! the voltage on open circuit b! the voltage with rated load switched M@ c! the voltage off load 11%. f the correct supply were connected to a :6 shunt motor which had lost its residual magnetism it would a! fail to run b! run in the reverse direction c! run normally 11#. a! b! c!
A loss of electrical insulation results in a short circuit between the supply and earth an open circuit between the supply and earth an open circuit in the supply
115. A :6 circuit containing a total resistance of 100 ohms has a current flow of 250 mA. The power dissipated in the circuit is a! 0.# watts b! ".25 watts c! 5 watts 11". a! b! c!
9ower is the rate of doing wor. t is measured in Foulessecond wattssecond Foules & seconds
11$. a! b! c!
MhmJs law states that e.m.f. = current divided by resistance resistance = current divided by e.m.f. current = e.m.f. divided by resistance
11/. f 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
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Module 3 – Electrical Fundamentals Sample Questions
114. a! b! c!
Mne purpose of a growler test is to determine the presence of a shorted armature an out?of?round commutator a broen field lead
120. Through which material will magnetic lines of force pass the most readily a! aluminium b! iron c! copper 121. a! b! c!
-lectricity conducts through solids only solids and li'uids vacuum
122. The secondary coil of a transformer has 1500 turns and 10 N resistance. The primary coil has 1 N resistance. ow many turns does the primary coil have a! 153000 b! 1503000 c! 135003000 12%. Two batteries 12V and #0 Ah each are in series. What is the total capacity a! 12V /0 Ah b! 2#V /0Ah c! 2#V #0 Ah 12#. n a star wound primary transformer3 how could you wind the secondary winding a! star only b! delta only c! either delta or star 125. a! b! c!
The phases in supply to a 2 phase motor are electrically 40 degrees apart from each other 1/0 degrees apart from each other 120 degrees apart from each other
12". A %0 >VA rated generator has a power factor of 0./. What is its ma&imum consistent power a! %0 >W b! 2# >W c! %$.5 >W
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Module 3 – Electrical Fundamentals Sample Questions
12$. A 50 K) capacitor is fed with a current of 25 mA. ow long will it tae to charge it to 100V a! 1 s b! 0.2 seconds c! 12 minutes 12/. The total resistance of the circuit shown is
a! 1.%% Mhms b! 12 Mhms c! % Mhms 124. a! b! c!
A step up transformer has one winding two windings three windings
1%0. a! b! c!
The three voltages of a three phase generator are connected independently of each other in series with each other in parallel with each other
1%1. a! b! c!
-.(.). in an electric circuit corresponds to what in a magnetic circuit mmf flu& reluctance
1%2. a! b! c!
Time constant of an inductor is +; +; +2;
1%%. a! b! c!
9ermanent magnets have high reluctance3 low coercive force low reluctance3 high coercive force high reluctance3 high coercive force
1%#. a! b! c!
A.6. value that can produce the same heat as :.6. is called r.m.s value average value pea value
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Module 3 – Electrical Fundamentals Sample Questions
1%5. a! b! c!
f a battery has got low internal resistance3 then on load voltage will be greater than no load voltage no load voltage will be greater than on load voltage no load voltage will be the same as on load voltage
1%". n a parallel ;3 +3 6 circuit3 the value of the capacitor is 'uadrupled3 then the value of the impedance would a! reduce b! increased c! remain the same 1%$. n a circuit 6 = 25 microfarads and the current flow is #0 microamps for # seconds. What is the voltage a! 12./V b! ".#V c! %.2V 1%/. 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! # V 1%4. The power in a circuit when voltage and resistance is given can be found by a! V&; b! V&V ; c! V&V&; 1#0. a! b! c!
A pie*oelectric device generates electricity through pressure friction light
1#1. a! b! c!
6onventional current flow inside a battery is from anode to cathode cathode to anode either anode to cathode or cathode to anode3 depending on the active elements
1#2. a! b! c!
9otentiometers are used as a variable voltage source variable resistor variable current source
1#%. n 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 Page 18
Module 3 – Electrical Fundamentals Sample Questions
1## a! b! c!
6alculate the speed of a #00 *3 # pole machine 123000 rpm "000 rpm /000 rpm
1#5. a! b! c!
The purpose of end travel microswitch in a linear actuator is to remain closed and opens at end travel only remain open and closes at end travel only remain open during normal operation and only close if the actuator overruns its stops
1#". a! b! c!
+inear actuators used in aircraft are of split field series wound type. split field shunt wound type compound wound type
1#$. a! b! c!
f a generator spars3 a possible reason is The brush springs are loose The brushes have been placed around the magnetic coil (agnetic flu& deflecting the -()
1#/. a! b! c!
The charge on a proton is neutral positive negative
1#4. a! b! c!
n conventional current flow3 what is )lemingJs right hand rule used for (otors Cenerators nductors
150. a! b! c!
n a capacitive circuit3 if the fre'uency is increased the current increases impedance increases reactance remains the same
151. a! b! c!
Three 12 D) capacitors are in series. The total capacitance is 12 D) # D) %" D)
152. A 500 ohm resistor carries a % amp current. What is the power dissipated a! 5 W b! #.5 W c! 500 W
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Module 3 – Electrical Fundamentals Sample Questions
15%. a! b! c!
A paramagnetic material has a relative permeability less than unity greater than unity e'ual to unity
15#. What is the 9: of a circuit which has a #0 mA current and a 1 ohm resistance a! #00 V b! # V c! #0 V 155. a! b! c!
The time constant of a capacitor is the time for the emf to reach %"./E of ma&imum the current to reach $0.$E of ma&imum to reach ma&imum current
15". The secondary winding of a transformer has an impedance of 10 ohms and 1500 turns. )or the primary winding to have an impedance of 1 ohm3 how many turns must it have a! 153000 b! 1503000 c! 135003000 15$. a! b! c!
A potentiometer has which of the following properties % terminals preset values wire wound
15/. it a! b! c!
A % ohm resistor dissipates 2$ Watts. ow much current flows through %A 4A 0.15 A
154. a! b! c!
n a 2 phase generator3 how far apart are the windings electrically #5o 40o 1/0o
1"0. a! b! c!
The , unit of wor is Boules per second 7Watts! >ilogram metres ? force Boules per metre
Page 2!
Module 3 – Electrical Fundamentals Sample Questions
1"1. n the circuit below3 what happens to the total circuit impedance if + is tripled
a! ncreases b! ;emains the same c! ;educes 1"2. a! b! c!
n a voltaic cell3 what is the build?up on the cathode called 9olari*ation ,ulphation ydration
1"%. A sine wave has a periodic time of 0.5 milliseconds. What is the fre'uency a! 200 * b! 2 * c! 20 * 1"#. Three branches in a circuit have currents entering of %A3 # 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 1"5. a! b! c!
Where are the output windings on an A6 generator ,tator ;otor with slip rings ;otor with commutator
1"". f the field strength of a generator is doubled3 and the speed is doubled3 the output -() will a! 'uadruple b! double c! stay the same 1"$. a! b! c!
f the rate of change of current is halved3 mutual inductance will double stay the same halve
Page 21
Module 3 – Electrical Fundamentals Sample Questions
1"/. f a capacitor of 50 microfarads has a current of 25 mA3 how long does it tae to charge to 100 V a! 200 milliseconds b! 200 seconds c! 150 seconds 1"4. n a Wheatstone Hridge3 the ammeter reads *ero3 and the variable resistor is adFusted to 5 ohms. ;esistor 9 has a value of 10 ohms and O has a value of 100 ohms. What is the value of the unnown resistor a! 0.5 ohms b! 5 ohms c! 50 ohms 1$0. a! b! c!
n a tuned circuit at resonance3 the circuit will be inductive resistive capacitive
1$1. a! b! c!
The time constant for an inductor is +; ;+ +&;
1$2. a! b! c!
n a :6 motor the pole pairs are embedded within the field coils part of the armature connected to the brush gear
1$%. a! b! c!
-ddy currents in a transformer core are reduced by decreasing the thicness of the laminates increasing the thicness of the laminates maing the core from a solid bloc
1$#. Transformer copper loss on full load is 220 Watts. Mn half load the loss will be a! 110 Watts b! ##0 Watts c! 55 Watts 1$5. a! b! c!
The earthJs magnetic field is greatest at the magnetic poles geographic poles magnetic e'uator
1$". a! b! c!
f a 1 ohm circuit produces a 50 W output3 the phase angle is 0o 40o #5o
Page 22
Module 3 – Electrical Fundamentals Sample Questions
1$$. a! b! c!
A series wound :6 motor3 the field has few turns of thic wire few turns of thin wire many turns of thin wire
1$/. 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 1$4. a! b! c!
What is a molecule The smallest part of a compound The smallest part of an electron The smallest part of an atom
1/0. a! b! c!
A coulomb is one ampere per second one ampere & second one second per ampere
1/1. n a circuit containing three resistors of e'ual value connected in parallel3 one resistor goes open circuit. The current in the other two resistors will a! increase b! decrease c! remain the same 1/2. a! b! c!
20 amperes flow for 20 seconds. ow many coulombs has flowed #00 20 1
1/%. a! b! c!
An atom is the smallest part of an element that retains its characteristics the smallest part of a compound that can e&ist independently the smallest particle of matter
1/#. a! b! c!
A neutron is a particle which is contained within the nucleus of most atoms orbits the nucleus of the atom contained in the nucleus of all atoms
1/5. a! b! c!
An electric current is a flow of electrons from a positively charged area to a negatively charged area protons from a positively charged area to a negatively charged area electrons from a negatively charged area to a positively charged area
Page 23
Module 3 – Electrical Fundamentals Sample Questions
1/". a! b! c!
An element could be considered to be a conductor if it has a large number of electrons a large number of electrons in its outer orbit a small number of electrons in its outer orbit
1/$. a! b! c!
A volt can be considered to be a unit of electrical pressure 'uantity of electrical energy unit of electrical power
1//. a! b! c!
f the resistance of an electrical circuit is increased the voltage will increase the current will increase the current will decrease
1/4. have a! b! c!
f 2 coulombs flowed through a circuit in 2 seconds3 the circuit would 2 volts 9: 2 amps 1 amp
140. a! b! c!
n general3 increasing the cross sectional area of an electrical cable enables it to carry more current enables it to carry more voltage increases its resistance
141. a! b! c!
:oubling the running time of an electrical machine would double the Foules used double the watts used double the current used
142. a! b! c!
What is %.25 volts in millivolts %.25 millivolts %3250 millivolts %253000 millivolts
14%. a! b! c!
-lectromotive force is measured in Watts Mhms Volts
14#. a! b! c!
,i& resistors each of " ohms would be %" ohms in parallel 1 ohm in series 1 ohm in parallel
145. a! b! c!
A capacitor in a single phase motor is to provide a phase shift prevent sparing at the switch provide smoothing Page 24
Module 3 – Electrical Fundamentals Sample Questions
14". a! b! c!
The mass of an atom is contained mainly in the electron nucleus proton
14$. a! b! c!
The line voltage from a generator with a delta type connection will be higher than the phase voltage lower than the phase voltage the same as the phase voltage
14/. a! b! c!
Mn a linear actuator3 the field cutoff coil will be energi*ed when the actuator is running the actuator is not running only as the actuator commences movement
144. >irchhoffJs law states a! the algebraic sum of all the voltages entering or leaving a series of components will be e'ual to *ero b! the algebraic sum of all the currents entering or leaving a series of components will be e'ual to one c! the inverse sum of all the voltages entering or leaving a series of components will be e'ual to one 200. a! b! c!
The lines of magnetic flu& from a magnet will repel each other attract each other have no effect upon each other
201. a! b! c!
A photo*oidal cell produces electricity when subFected to light heat pressure
202. a! b! c!
A thermocouple indicator is basically a type of milliammeter millivoltmeter milliohmeter
20%. An electric motor produces a force of 5 @ at a distance of 0.2m from the centre of rotation and rotates at a speed of 100 revssec. The motors output is a! 100 horsepower b! "2/.# watts c! %1#.2 watts 20#. a! b! c!
A potentiometer varies voltage current resistance
Page 25
Module 3 – Electrical Fundamentals Sample Questions
205. a! b! c!
,tarter motors are usually series wound compound wound shunt wound
20". ow can it be determined if a transformer winding has some of its turns shorted together a! measure the input voltage with an ohmmeter b! the transformer will get hot in normal operation c! the output voltage will be high 20$. 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 e'ual 20/. a! b! c!
What does a rectifier do 6hanges direct current into alternating current 6hanges alternating current into direct current ;educes voltage
204. a! b! c!
Two 12V #0 amp hour batteries connected in parallel will produce 2#V /0 ah 12V /0 ah 2#V #0 ah
210. a! b! c!
When an atom loses or gains an electron it is called a current an ion a molecule
211. A circuit has a resistance of 50 ohms and an inductance of 0.2 enry. f it is connected to a 200 volt 50 * supply the reactance will be a! %1.#2 ohms b! "2./# ohms c! ".2/# ohms 212. A 2#?volt source is re'uired to furnish #/ watts to a parallel circuit consisting of four resistors of e'ual value. What is the voltage drop across each resistor a! 12 volts b! 2# volts c! % volts 21%. Mf the following which pair of materials would most readily become magneti*ed a! copper and steel b! nicel and bron*e c! iron and steel Page 26
Module 3 – Electrical Fundamentals Sample Questions
21#. a! b! c!
The formula for resistance in series is ;T = ;1 G ;2 G ;%...;@ ;T = ;1 & ;2 & ;%...;@ 1;T = 1 7;1 & ;2 & ;% ...;@!
215. a! b! c!
The core material used for an electromagnet is soft iron because it demagneti*es easily its magnetism is not easily destroyed it retains most of its flu& density when demagneti*ed
21". What is the combined value of resistances of # ohm and " ohm connected in parallel a! 2# ohm b! 2.# ohm c! 0.2# ohm 21$. a! b! c!
9ermanent magnets in an A6 generator are to provide initial e&citation to control the fre'uency to rectify the current
21/. The method of ascertaining the voltage of a standard aircraft lead?acid battery is by checing a! the voltage off load b! the voltage on open circuit c! the voltage with rated load switched M@. 214. a! b! c!
Cenerator brushes are normally made of carbon brass steel
220. a! b! c!
f the voltage across a resistor is doubled the current is doubled the resistance is halved the current is halved
221. As the generator load is increases 7within its rated capacity!3 the voltage will a! remain constant and the amperage output will decrease b! decrease and the amperage output will increase c! remain constant and the amperage output will increase 222. a! b! c!
f a number of resistors are connected in parallel3 the total resistance is the same as the lowest smaller than the lowest greater than the lowest
Page 27
Module 3 – Electrical Fundamentals Sample Questions
22%. a! b! c!
A charged body is said to have a surplus or deficiency of electrons a surplus of protons a deficiency of neutrons
22#. a! b! c!
The ratio between apparent power and true power is the efficiency power rating power factor
225. a! b! c!
The voltage output of a generator is controlled by varying the current of the output varying the resistance of the output varying the current of the field
22". The total current flowing in a circuit of 200 lamps in parallel3 each of a resistance of #00 ohm and connected across an input of 100 volts is a! 50 amps b! 25 amps c! #0 amps 22$. The current flowing in the armature of a :6 motor is e'ual to a! 7applied volts ? generated volts! & armature resistance b! applied volts G generated volts armature resistance c! applied volts ? generated volts armature resistance 22/. n the circuit shown the 2# 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! " ohms 224. a! b! c!
Mne advantage of using Ac electrical power in aircraft is the greater ease in stepping the voltage up or down A6 electrical motors can be reversed while dc motors cannot the effective voltage is 1.#1 times the ma&imum instantaneous voltageP therefore3 less power input is re'uired
Page 28
Module 3 – Electrical Fundamentals Sample Questions
2%0. a! b! c!
The 'uill drive on an aircraft generator maes possible the use of roller bearings at the drive end damps out vibrations damps out any commutator ripple
2%1. 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 2%2. a! b! c!
When resistors are in parallel3 the total resistance is smaller than the smallest resistor the sum of all the resistors larger than the smallest resistor
2%%. What device is used to convert alternating current3 which has been induced into the loops of the rotating armature of a :6 generator into direct current as it leaves the generator a! a commutator b! an inverter c! a rectifier 2%#. a! b! c!
Two similar 12 v batteries connected in parallel will produce 2#V e.m.f. with twice the capacity of each battery 2#v e.m.f. with the same capacity as each battery 12V e.m.f. with twice the capacity of each battery
2%5. Qnless otherwise specified3 any values given for current or voltage in an A6 circuit are assumed to be a! ma&imum values b! effective values c! instantaneous values 2%". a! b! c!
f a heavy mechanical load is removed from a series motor the speed will increase and the armature current will decrease the speed will decrease and the armature current will decrease the speed will increase and the armature current will increase
2%$. n a vector diagram showing the magnitude and direction of the inductance3 capacitance and resistance in an A6 circuit a! the inductive reactance would be in opposition to the capacitive reactance and resistance at 40 degrees b! the inductive and capacitance reactance would be additive with the resistance subtractive c! it is impossible to show values of this ind using vectors
Page 2
Module 3 – Electrical Fundamentals Sample Questions
2%/. f service @o. 1 is isolated from the supply busbar shown3 there will be
a! an increase in supply voltage b! a decrease in supply voltage c! a decrease in total current consumption 2%4. 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 2#0. a! b! c!
The voltage of a secondary cell is determined by the number of plates determined by the area of the plates determined by the active materials on the plates
2#1. The basis for transformer operation in the use of alternating current is mutual a! reactance b! inductance c! capacitance 2#2. The e&citer winding in a brushless A6 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 A6 windings 2#%. f the cross?sectional area of a conductor is doubled3 with voltage constant3 the current will a! halve b! double c! remain constant 2##. a! b! c!
-ddy currents in a transformer can be reduced by using a special non metallic material using a single solid piece of metal laminations
2#5. a! b! c!
The term used to denote the strength of a magnetic field is retentivity hysterisis flu& density Page 3!
Module 3 – Electrical Fundamentals Sample Questions
2#". f 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% amp b! it cannot be found without nowing the applied voltage c! 1 amp 2#$. At resonant fre'uency the phase difference between the voltage and current of an A6 supply feeding an inductive and capacitive networ is a! 0 degrees b! 1/0 degrees c! 40 degrees 2#/. 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 2#4. 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! 1## milliwatts 250. a! b! c!
The voltage in a series circuit is different in each component is the same in each component is less than it would be in a parallel circuit
251. A6 a! b! c!
Which aircraft circuit would be most liely to use fre'uency wild 200V windscreen heating hydraulic pump standby compass
252. a! b! c!
Why are the iron cores of most induction coils laminated To reduce the effects of eddy currents To increase the core permeability To reduce the core reluctance
25%. A #/?volt source is re'uired to furnish 142 watts to a parallel circuit consisting of three resistors of e'ual value. What is the value of each resistor a! 12 ohm b! # ohm c! %" ohm
Page 31
Module 3 – Electrical Fundamentals Sample Questions
25#. a! b! c!
f voltage is 100V3 resistance is 25 ohms3 what is the current 2500 amperes # amperes 0.# amperes
255. a! b! c!
A soft iron core is used in an -+-6T;M magnet because it has C permeability and C coercivity it has C permeability and +MW coercivity it has +MW permeability and C coercivity
25". a! b! c!
The resistance to electrical flow in a wire depends on the diameter3 length3 material of wire and temperature the material only ? copper or aluminum the length and material of the wire only
25$. a! b! c!
A transformer should always have its secondary open circuit or on load secondary shorted or on load primary shorted or off load
25/. ow can the direction of rotation of a :6 electric motor be changed a! interchange the wires which connect the motor to the e&ternal power source b! reverse the electrical connections to either the field or armature windings c! rotate the positive brush one commutator segment 254. a! b! c!
An A6 generatorJs fre'uency will always be constant regardless of the generators drive speed vary with changes in field strength be proportional to the ;9( at which it is driven
2"0. a! b! c!
A short circuit between the supply and earth does not matter if the circuit uses the aircraft earth as a return could be very dangerous as the current drawn will be very high is not dangerous as the current drawn will be low
2"1. When two coils are lined by a common flu&3 a voltage can be induced in one by a changing current in the other. This process is nown as a! mutual induction b! the magnetic effect c! self induction 2"2. A circuit consists of % ohm3 5 ohm and 12 ohm resistors in series3 the current flowing in the 5 ohm resistor is 10 amps. What is the applied voltage a! 100v b! 10v c! 200v
Page 32
Module 3 – Electrical Fundamentals Sample Questions
2"%. a! b! c!
6opper is an inferior conductor to aluminum when comparing weight for weight load for load 6,A with 6,A
2"#. a! b! c!
n an A6 circuit how is the value of true power calculated Hy volts multiplied by amps multiplied by power factor Hy wattmeter readings multiplied by power factor Hy voltmeter readings multiplied by ammeter readings
2"5. a! b! c!
A fre'uency wild A6 generator is used for instruments and navigation de?icing loads any A6 load
2"". Which of the following is not one of the purposes of interpoles in a generator a! ;educe field strength b! Mvercome armature reaction c! ;educe arcing at the brushes 2"$. ratio a! b! c!
Which of the following would be used to calculate transformer turns primary turns R secondary turns primary turns L secondary turns secondary turns L primary turns
2"/. a! b! c!
A good electrical insulator is a material which has more protons than electrons has its electrons tightly bound to their parent atoms contains a large number of positive ions
2"4. a! b! c!
To reverse the direction of a series motor the direction of the current through the field is reversed a second series field is fitted the direction of the current through the field and the armature is reversed
2$0. ow many cycles of A6 voltage are produced in a si&?pole alternator of the revolving?field type3 with each revolution of the rotor a! )our b! ,i& c! Three 2$1. The variable fre'uency output from an A6 generator is used for a! supplying non?inductive loads b! the A6 supply instead of using inverters c! driving A6 operated instruments
Page 33
Module 3 – Electrical Fundamentals Sample Questions
2$2. a! b! c!
The capacitance of a capacitor is dependant upon the type of material separating the plates the rate of change of current in the circuit the charge on it
2$%. A piece of e'uipment is rated at $50 watts and the applied voltage is %0 volts. The value of the protection fuse should be a! 20 amps b! %0 amps c! 15 amps 2$#. a! b! c!
The current consumed by a :6 starter motor will remain relatively constant over the starting speed range increase as the engine speed increases decrease as the engine speed increases
2$5. When different rated capacitors are connected in parallel in a circuit3 the total capacitance is a! e'ual to the capacitance of the highest rated capacitor b! less than the capacitance of the lowest rated capacitor c! e'ual to the sum of all the capacitances 2$". 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 2$$. a! b! c!
ow are generators rated mpedance at rated voltage Amperes at rated voltage Watts at rated voltage
2$/. a! b! c!
n a single phase A6 generator3 fre'uency is determined by the generator speed controlling the current flow through the voltage field windings the number of pairs of poles
2$4. a! b! c!
The ris of a fire due to static electricity is overcome by fitting static wics and insulating all metal components by connecting all metal components by bonding by fitting static wics and isolating the battery from inflammable gas sources
2/0. a! b! c!
:ue to armature reaction in a :6 motor the trailing pole tips are magnetically weaened the leading pole tips are magnetically weaened the magnetic flu& is restored by moving the (@A towards the C@A
Page 34
Module 3 – Electrical Fundamentals Sample Questions
2/1. Two resistors are connected in series and have an e.m.f. of V volts across them. f the voltages across the resistances are V1 and V2 then by >irchhoffJs law a! V = V1 G V2 b! V2 = V1 G V c! V1 = V2 G V 2/2. When an electrical supply becomes open?circuit a! the loss of continuity will prevent its component from functioning b! the fuse or circuit breaer should isolate the circuit due to the increased current drawn c! the component will operate normally but will not switch off 2/%. ,ome 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 2/#. a! b! c!
The amount of electrical power for a given generator weight is determined by the si*e of the aircraft greater for :6 generator greater for A6 generator
2/5. a! b! c!
When resistors are in parallel the total current is e'ual to the current through one resistor the sum of the currents the reciprocal of all the currents
2/". What is the ampere?hour rating of a storage battery that is designed to deliver #5 amperes for 2.5 hours a! 40.0 ampere?hour b! 112.5 ampere?hour c! #5.0 ampere?hour 2/$. ow much power must a 2#?volt generator furnish to a system which contains the following series loads 5 ohm3 % ohm and 12 ohm a! #50 watts b! #02 watts c! 2/./ watts 2//. a! b! c!
A volt meter is connected in series or parallel in parallel in series
2/4. a! b! c!
What polarity do interpoles tae in a :6 motor The same as the ne&t main pole behind in the direction of rotation -ither3 provided they lay on the (@A The same as the ne&t main pole ahead in the direction of rotation Page 35
Module 3 – Electrical Fundamentals Sample Questions
240. a! b! c!
Mn a typical A6 generator the output is taen direct from the rotor via slip rings direct from the e&citer direct from the stator windings
241. ,ince electrical supplies taen from a bus?bar are in parallel3 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 consumption3 it would reduce the voltage 242. a! b! c!
Mne 9icofarad is 1 & 1012 farad 1 & 10?" farad 1 & 10?12 farad
24%. a! b! c!
Which of these will cause the resistance of a conductor to decrease :ecrease the length or the cross?sectional area :ecrease the length or increase the cross?sectional area ncrease the length or decrease the cross?sectional area
24#. a! b! c!
The purpose of bonding is to give generated static an easy return path to the generator stop different potentials developing with subse'uent fire riss ensure all components have been securely fitted
245. a! b! c!
The ,.. unit of magnetic flu& density is the Weber enry Tesla
24". a! b! c!
What is the principal advantage of the series?wound dc motor +ow starting tor'ue ,uitable for constant speed use igh starting tor'ue
24$. a! b! c!
nterpole windings fitted to :6 series wound generators are in series with the field in parallel with the armature in series with the armature
24/. Mne of the chief advantages of alternating current is that it can be transmitted at a high voltage with a low power lossP the voltage can then be changed to any desired value of a! A6 by means of transformers b! :6 by means of transformers c! :6 by means of inverters
Page 36
Module 3 – Electrical Fundamentals Sample Questions
244. An A6 generator is producing the re'uired voltage but a higher fre'uency than that re'uired. To remedy this3 the following action must be taen a! :ecrease the speed of the prime mover3 and then decrease the strength of the field b! :ecrease the speed of the prime mover c! :ecrease the speed of the prime mover3 and then increase the strength of the field %00. ow many amperes will a 2/?volt generator be re'uired to supply to a circuit containing five lamps in parallel3 three of which have a resistance of " ohms each and two of which have a resistance of 5 ohms each a! 25.2% amperes b! 1 ampere c! 1.11 amperes %01. The area of a hysteresis loop is proportional to the a! energy dissipated in putting the material through a complete cycle of magneti*ation and demagneti*ation b! relative permeability of the material being magneti*ed c! energy absorbed in completely demagneti*ing the material %02. 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 %0%. When more than two inductors of different inductances are connected in parallel in a circuit3 the total inductance is a! e'ual to the sum of the individual inductances b! less than the inductance of the lowest rated inductor c! e'ual to the inductance of the highest rated inductor %0#. a! b! c!
What polarity do interpoles tae in a :6 generator the same as the ne&t main pole ahead in the direction of rotation the same as the ne&t main pole behind in the direction of rotation either3 providing they lay on (
[email protected].
%05. What happens to the resistance of a copper conductor when the temperature increases a! t increases b! t decreases c! t remains the same
Page 37
Module 3 – Electrical Fundamentals Sample Questions
%0". 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 %0$. a! b! c!
The core material used for an electromagnet is soft iron because it demagneti*es easily it retains most of its flu& density when demagneti*ed its magnetism is not easily destroyed
%0/. The switch on a :6 circuit containing a fully charged capacitor is opened. The voltage across the capacitor a! drops immediately to *ero b! starts to fall e&ponentially to *ero c! remains e'ual to the original charging voltage supply %04. n a % phase generator with balanced load3 the potential between the neutral point and earth is a! e'ual to line volts b! e'ual to phase volts c! *ero volts %10. 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! 1## milliwatts %11. An increase in which of the following factors will cause an increase in the inductive reactance of a circuit a! ;esistance and capacitive reactance b! ;esistance and voltage c! nductance and fre'uency %12. a! b! c!
n transformer operation3 hysteresis losses are current overcoming coil resistance induced current in the iron core energy wasted in reversing core magneti*ation
%1%. The starting current of a series?wound :6 motor3 in passing through both the field and armature windings produces a a! low starting tor'ue b! speed slightly higher when unloaded c! high starting tor'ue
Page 38
Module 3 – Electrical Fundamentals Sample Questions
%1#. a! b! c!
A non?magnetic metal has no permeability has high retentivity is a poor conductor
%15. a! b! c!
The power output of an A6 parallel generator system is measured in >VA >W >VA;, amperes
%1". a! b! c!
The shape of the output waveform of an A6 generator is nown as a sine wave cosine wave fre'uency wave
%1$. n a circuit containing three resistors of e'ual value connected in series and one of the resistors short circuits3 the effect is for the current in the other two resistors to a! increase b! remain the same c! decrease %1/. a! b! c!
To increase the speed of a shunt motor a resistance is placed in series with the armature in parallel with the field in series with the field
%14. a! b! c!
)re'uency 7*! is the number of cycles per revolution minute second
%20. a! b! c!
n a series resistive circuit the total voltage e'uals the difference between the individual voltages the total voltage is e'ual to the sum of the individual voltages the total voltage is the same as the highest individual
%21. a! b! c!
The current in a :6 circuit containing a fully charged capacitor is *ero is dependent upon the si*e of the capacitance of the capacitor ma&imum
%22. a! b! c!
The sum of the instantaneous -.(.)Js in a three phase system is e'ual to the line voltage three times the phase voltage *ero
Page 3
Module 3 – Electrical Fundamentals Sample Questions
%2%. a! b! c!
A capacitor is a barrier to both A.6 :.6
%2#. a! b! c!
Mne revolution of a three phase generator will produce % cycles 2 cycles 1 cycle
%25. f the @orth pole of a magnet is brought nearer to the @orth 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 %2". A 200 volt motor is taing 10 amperes armature current3 the armature resistance is 0.1 ohm. The H.-() under these conditions will be a! 201 volts b! 144 volts c! 1 volt %2$. What is the effect of inserting an iron core into a current carrying coil a! The flu& density of the original magnetic field produced by the coil is increased b! The flu& density of the original magnetic field remains constant c! The core tends to move from a stronger to a weaer part of the field %2/. What is the total capacitance of a parallel circuit containing three capacitors with capacitance of 0.25microfarad3 0.0%microfarad3 and 0.12microfarad3 respectively a! 0.0# D) b! 0.0# p) c! 0.# D) %24. At resonant fre'uency the phase difference between the voltage and current of an A6 supply feeding an inductive and capacitive networ is a! 0 degrees b! 1/0 degrees c! 40 degrees %%0. a! b! c!
The fre'uency of a power wave in an A6 resistance circuit is the same as the fre'uency for voltage and current half the fre'uency for voltage and current twice the fre'uency for voltage and current
Page 4!
Module 3 – Electrical Fundamentals Sample Questions
%%1. The reading on the ammeter in the circuit shown is
a! %A b! "A c! 12A %%2. a! b! c!
The JAJ phase of a three phase power system is colour coded blue yellow red
%%%. The total resistance of the circuit shown is
a! 12 Mhms b! % Mhms c! $.5 Mhms %%#. What is a method used for restoring generator field residual magnetism a! )lash the fields b! ;eseat the brushes c! -nergi*e the armature %%5. a! b! c!
A 1D) capacitor is e'uivalent to 0.0003001 )arads 130003000 )arads 0.001 )arads
%%". The opposition offered by a coil to the flow of alternating current is called 7disregard resistance! a! impedance b! reluctance c! inductive reactance %%$. a! b! c!
The tolerance of the A6 generator fre'uency is #0 * 10 * 20 *
Page 41
Module 3 – Electrical Fundamentals Sample Questions
%%/. A high surge of current current is re'uired re'uired when a :6 electri electricc mot motor or is first first started. As the speed of the motor increase a! the applie appliedd emf increases increases proportion proportionally ally b! the counte counterr emf decreases decreases proportion proportionally ally c! the counter counter emf builds builds up and and opposes opposes the applied applied emf3 emf3 thus reducin reducingg the current flow through the armature %%4. The various parts of an aircraft airframe are maintained at the same potential by a! the the supp supply ly bus bus?b ?bar arss b! static static discha discharge rge wics wics c! bonding ing %#0. %#0. a! b! c!
When When two two capa capacit citors ors are connec connected ted in seri series es the charge charge stored stored on eeach ach is directly directly proportio proportional nal to its its capacitan capacitance ce the charge charge stored stored on each is the the sa same me the charge charge stored stored on each is invers inversely ely proportion proportional al to the voltage voltage across it
%#1. %# 1. a! b! c!
Airc Aircra raft ft gen gener erat ator orss are are cool cooled ed by by oil cooling cooling radiators radiators around around the main main body body fuell coolin fue coolingg radiat radiators ors ram ai air
%#2. %# 2. The The vol volta tage ge of of an A6 gen gener erat ator or a! rises to ma& in one one direction3 direction3 falls falls to *ero *ero and rises rises in the the same same direction b! rises to ma& in one one direction direction then then falls to *ero then then rises rises to ma& in the opposite direction c! rises to ma& ma& in one direction direction and remains remains %#%. %#%. a! b! c!
The charge charge on a capaci capacitor tor is e&p e&pres ressed sed as the the rat ratio io O OV V the the pro produ duct ct O & V the the pro produ duct ct 6 & V
%###. %# a! b! c!
A sh shun untt is used with ith an amm mmeeter ter an oh ohmm mmet eter er a vo voltme ltmete terr
%#5. The resist resistance ance of the the current current return return path through through the the aircraft aircraft is is always always considered negligible3 provided the a! gen genera erator tor is prop properly erly grou grounde ndedd b! voltage voltage drop drop across across the circuit circuit is chece checedd c! struct structure ure is is ade'u ade'uate ately ly bonde bondedd
Page 42
Module 3 – Electrical Fundamentals Sample Questions
%#". %#". a! b! c!
An amme ammeter ter is connec connected ted int intoo a circui circuitt in para pa ralllleel shunt series
%#$. it a! b! c!
When hand handling ling a high voltage voltage capacitor capacitor in an electrical electrical circuit3 circuit3 be sure has a full full charge charge before before removing removing it from from the circuit circuit is fully disch discharged arged before before removin removingg it from the the circuit circuit has at least least a residual residual charg chargee before before removing removing it from from the circuit circuit
%#/. When a circuit circuit with with a series series inductance inductance and capac capacitanc itancee is at at resonant resonant fre'uency a! the current current in in th thee circuit circuit decreases decreases b! the impedanc impedancee of the circuit circuit is such that that the voltage voltage is in phase phase with with the current c! the impedanc impedancee of the circuit circuit is such that that the voltage voltage leads leads the current current by e&actly 40 degrees %#4. %#4. a! b! c!
n an an A6 A6 circu circuit3 it3 the the eff effect ective ive voltag voltagee is e'uall to the e'ua the ma&imum ma&imum insta instantane ntaneous ous voltag voltagee greater greater than the the ma& ma&imum imum instan instantane taneous ous voltag voltagee less than the ma&imu ma&imum m instanta instantaneou neouss voltage voltage
%50. Mn a co %50. combi mbined ned :6 starte starterr ? gene generat rator or sys system tem a! the voltage voltage regulato regulatorr is connected connected to the the shunt field field after the the start cycle cycle is completed b! the series series coil is open open circuit circuit during during the engine engine start se'uen se'uence ce c! the voltage voltage regulator regulator controls controls the start start se'uence se'uence during engine engine starting starting %51. A pure capac capacitor itor33 inductor inductor and and resistor resistor are are connecte connectedd in series series and and the voltage drops across each are 10V and the total current flowing in the circuit is 1A. ow much much true power is the circuit consuming consuming a! %0VA b! %0W c! 10W %52. f a capac capacitor itor 1D) 1D) and and an induct inductor or 10m 10m are connecte connectedd in paralle parallell what what is their appro&imate resonant fre'uency a! "2* b! %.2(* c! 1."* %5%. Which wave form is is stepped stepped positive positive and and ne negativ gativee with with une' une'ual ual lengt lengthh sides a! Trap Trape* e*oi oida dall wave wave b! ;ect ;ectan angu gula larr wav wavee c! ,aw ,aw too tooth th wave wave
Page 43
Module 3 – Electrical Fundamentals Sample Questions
%5#. The value value of of an A6 sine sine wave wave tha thatt will give give an e'uivalent e'uivalent heating heating effect effect in a :6 resistor is the a! av aver erag agee valu valuee b! ;(, ;(, value alue c! pe peaa value lue %55. %5 5. a! b! c!
Wher Wheree is the the magn magnet etic ic dip dip lea least st 9oles -'uator so soclin clinaals
%5". %5". a! b! c!
The diel dielect ectric ric cons constan tantt of a capaci capacitor tor is a measu measurem rement ent of the electrosta electrostatic tic energy energy storing storing capacity capacity of the capacitor capacitor dielectric dielectric the electric electrical al resistanc resistancee of the capacit capacitor or dielectric dielectric the electrica electricall repulsion repulsion of electron electronss within the the dielectric dielectric material material
%5$. To reverse reverse the the directio directionn of rotatio rotationn on a :6 shunt shunt motor motor33 you you must must change the direction of the current through a! the field field winding windingss or the armatu armature re winding windingss b! the armatu armature re wind winding ingss only only c! the field field windings windings and the armature armature winding windingss %5/. f the field %5/. field curr current ent to a shun shuntt wound wound :6 motor motor is decr decreas eased ed when when operating at a constant load3 the motor speed will a! reduce b! incr increa easse c! no nott cha hang ngee %54. %5 4. a! b! c!
An elec electr tric ic cu curr rren entt is is a surpl surplus us of of free free elect electron ron an e&cite e&citement ment of electron electronss in a met metal al an orde ordered red flo flow w of electr electrons ons
%"00. %" a! b! c!
An atom tom con onta tain inss mole mo leccules les hydr hy drog ogen en ele electro ctronns
%"1. %"1. a! b! c!
What What caus causes es a tran transfo sforme rmerr to be noisy noisy igh igh coil coil resi resist stan ance ce An air air gap gap in the the cor coree igh igh cor coree loss losses es
%"2. a! b! c!
6arbon ha has a negati neg ative ve tempera temperatur turee coeffici coefficient ent positive positive temperature temperature coefficie coefficient nt temper tem peratu ature re coeff coefficie icient nt of *ero *ero
Page 44
Module 3 – Electrical Fundamentals Sample Questions
%"%. a! b! c!
The pea factor for a sine wave is 0.$0$ 1.#1# 1.11
%"#. a! b! c!
f a motor is spinning at 50 cycles per second3 how long is 1 cycle 0.02 seconds 50 seconds 0./% seconds
%"5. a! b! c!
An integrated step input at une'ual time base produces a s'uare wave a sine wave a saw tooth wave
%"". a! b! c!
A capacitor in series and inductor in parallel mae what ind of filter Hand pass igh pass +ow pass
%"$. f a load in series has a current passing through it3 the magnetic field can be wored out by using a! the corscrew rule b! left hand rule c! right hand rule %"/. f the current flowing into a Function is 5A3 %A3 #A in and 10A out. What is the 5th wire carrying a! 2A in b! 2A out c! 5A out %"4. f an insulated conductor is placed near to a negatively charged rod3 the nearest end of the conductor becomes a! negatively charged b! positively charged c! @o change will occur %$0. f 2 resistors3 one red3 yellow3 blac3 gold and the other violet3 blue3 blac3 silver were replaced by a single resistor. gnoring tolerance3 what would the color coding be a! Hrown3 blac3 brown b! Hrown3 blac3 blac c! Hlac3 brown3 blac %$1. a! b! c!
Cermanium and silicon have how many electrons in their outer shell # 2 "
Page 45
Module 3 – Electrical Fundamentals Sample Questions
%$2. a! b! c!
f a free electron is given to another atom3 that atom is a positive ion negative ion valency atom
%$%. a! b! c!
f a nicad battery is not to be used immediately it should be stored fully charged fully dissipated dry
%$#. a! b! c!
A light heat sensitive cell is a transducer diode transistor
%$5. a! b! c!
n a mercury cell the steel casing is the positive terminal the negative terminal neither
%$". a! b! c!
To improve the life of a dry cell you would use more *inc use more electrolyte paste us a a pure carbon positive rod
%$$. What is the voltage at A
a! 2"V b! 2/V c! 2V %$/. a! b! c!
The unit for power is e'ual to @m Boules per second VoltsAmps
Page 46
Module 3 – Electrical Fundamentals Sample Questions
%$4. The source voltage in the circuit below is
a! 50V b! 200V c! 150V %/0. a! b! c!
The 5th colored band on a resistor represents the tolerance multiplier reliability or temperature coefficient
%/1. Three 12 microfarad capacitors in parallel. The overall circuit capacitance is a! # microfarads b! 1 microfarads c! %" microfarads %/2. a! b! c!
)lu& density will increase linearly with coercive force increase linearly with magnetic flu& decrease linearly with magnetic flu&
%/%. a! b! c!
A transformer with a 51 ratio has a 2#V output. What is the input 120 V :6 #./ V A6 120 V A6
%/#. A generator supplies 25 A3 # V and 50 W. What is the apparent power and the power factor a! 100 VA and 2 b! #00 VA and 0.5 c! 100 VA and 0.5
Page 47
Module 3 – Electrical Fundamentals Sample Questions
%/5. The mar?to?space ratio of the following waveform is
a! A to H H to 6 b! A to : : to c! : to : to 6 %/". a! b! c!
n a power circuit3 the purpose of an inductor is to dampen power surges to dampen current surges to dampen voltage surges
%/$. a! b! c!
When a number of ferrite pieces are grouped together3 they are semi?permanent magnets when :6 is passed through them can be used to store binary code electromagnets
%//. a! b! c!
Ampere turns is calculated by the number of turns multiplied by current divided by current multiplied by magnetic flu&
%/4. A conventional aircraft generator will be a! series wound b! delta wound c! star wound %40. ,torage of magnets should be a! in pairs end to end b! in a non magnetic po& c! in pairs with eeper plates %41. A circuit has 1 mega ohm and / microfarads. What is the time constant a! 1 second b! / seconds c! #0 seconds
Page 48
Module 3 – Electrical Fundamentals Sample Questions
%42. a! b! c!
6urrent in an inductive circuit will lead voltage lag voltage be at unity
%4%. a! b! c!
9ower factor of a generator is sin I cos I tan I
%4#. a! b! c!
n a an A6 motor3 the rotation of the (@A is the same as the rotation of the armature is opposite to the rotation of the armature is slightly less speed than the rotation of the armature
%45. n a wave wound generator with # poles3 what would be the minimum number of brushes a! # b! 2 c! / %4". a! b! c!
A capacitor rating is the ma&imum continuous voltage it can tae the voltage it will rupture at the voltage it will charge to
%4$. a! b! c!
n conventional flow3 the left hand rule applies to generators motors batteries
%4/. a! b! c!
6opper losses in a transformer are caused by circulating currents through the transformer the resistance in the windings wasting of the copper wires due to friction
%44. a! b! c!
in A6 generators3 0."%$ is ;(, average value form factor
#00. a! b! c!
n a % phase generator3 what angle are the phases to each other 1/0o 120o 0o
#01. a! b! c!
n a 2 phase generator3 what angle are the phases to each other 40o 1/0o 0o Page 4
Module 3 – Electrical Fundamentals Sample Questions
#02. a! b! c!
:elta wound line current is e'ual to phase current root % & phase current less than the phase current
#0%. a! b! c!
The multiplier color coding on a capacitor is in farads microfarads picofarads
#0#. a! b! c!
)orm )actor for a sine wave A6 output is 0.$0$ 1.#1# 1.1
#05. a! b! c!
n a simple voltaic cell the collection of ions on the cathode causes hydration sulphation polarisation
#0". a! b! c!
The electrolyte in a nicad battery would rise if the battery was discharging charging remaining at constant voltage
#0$. When a conductor is cut by magnetic lines of force an -() is induced. This is a! +en*Js +aw b! )aradayJs +aw c" >irchhoffJs +aw #0/. Two 2 volt 10A cells are connected in series3 the output voltage and the capacity would be a! 2 volt3 20 A b! # volt 10 A c! # volt 20 A #04. a! b! c!
The electrolyte in a nicad battery is cadmium hydro&ide nicel hydro&ide potassium hydro&ide
Page 5!
Module 3 – Electrical Fundamentals Sample Questions
#10. ;eferring to the drawing below3 if the volts dropped across the 20 ohm resistor is 10 volts3 the resistance of ;1 is
a! 20 ohms b! 1" ohms c! 2 ohms #11. a! b! c!
The atomic number of an atom is determined by the number of protons electrons neutrons
#12. a! b! c!
n a +eclanche cell the plates are made of mercury and lithium nicel and cadmium *inc and carbon
#1%. the a! b! c!
n a simple voltaic cell3 polari*ation reduces output voltage because of transfer of material between the anode and the cathode build up of hydrogen on the anode build up of hydrogen on the cathode
#1#. a! b! c!
When the temperature of the electrolyte in a battery increases3 the ,C goes up goes down remains the same
#1 5. a! b! c!
A #$ ilohm resistor has the following color code Sellow3 Violet3 Mrange Mrange3 Violet3 ;ed ;ed3 Mrange3 Sellow
#1". f the temperature of a pure metal is reduced to absolute *ero3 its resistance will be a! infinity b! practically *ero c! unaffected
Page 51
Module 3 – Electrical Fundamentals Sample Questions
#1$. The bridge circuit shown will be balanced when the value of the unnown resistor ; is
a! 1/ ohms b! 1# ohms c! 2 ohms #1/. The current in the circuit below is
a! 5 A b! 0.2 A c! 5 mA #14. n the previous 'uestion3 the power developed across the 10 ohm resistor is a! 250 mW b! 250 W c! 50 mW #20. What is represented by this diagram
a! 9otentiometer b! ;heostat c! Thermister Page 52
Module 3 – Electrical Fundamentals Sample Questions
#21. n the following circuit3 the input at 9 is # amps and at O is 5 amps. What is the voltage across the " ohm resistor
a! 5#V b! 1.5V c! "V #22. The unnown current in the networ below is
a! 22A b! %A c! #$A #2%. a! b! c!
The Watt can be e&pressed as Boules per second Boules & seconds ,econds per Boule
#2#. A single phase circuit has an input voltage of 100V. The current is 10A and the circuit has a power factor of 0.5. The true power is a! 1000W b! 50W c! 500W #25. a! b! c!
9ower in a :6 circuit is found by multiplying current by resistance multiplying the voltage by itself and dividing by the current multiplying the resistance by the current s'uared
Page 53
Module 3 – Electrical Fundamentals Sample Questions
#2". The total capacitance of the circuit shown is
a! #D) b! %"D) c! %D) #2$. is a! b! c!
When a capacitor is charged from a :6 supply3 the voltage time curve logarithmic e&ponential linear
#2/. a! b! c!
An electrolytic capacitor is used because it has a large physical si*e for a large capacity small physical si*e for a large capacity small physical si*e for low leaage current
#24. a! b! c!
An electrolytic capacitor would be used in circuits supplying heavy loads light loads heavy light loads
#%0. a! b! c!
The symbol for flu& density is H (()
#%1. a! b! c!
The hysteresis loop for a magnetic material is on a graph with total flu& against flu& density current against flu& density flu& density against magnetising force
#%2. To determine the direction of the magnetic field around a conductor you would use a! the corscrew rule b! )lemingJs left hand rule c! )lemingJs right hand rule #%%. a! b! c!
A material with a narrow hysteresis loop will have high retentivity will have low retentivity cannot be magnetised
Page 54
Module 3 – Electrical Fundamentals Sample Questions
#%#. a! b! c!
f a bar magnet is cut in half the magnet is destroyed two bar magnets are formed one bar magnet and one non?magnet is formed
#%5. The diagram shows a current carrying conductor in a magnetic field. The conductor will move
a! upwards b! downwards c! sideways #%". a! b! c!
The electromagnetic force between two charged bodies is proportional to the distance between them inversely proportional to the distance between them inversely proportional to the s'uare of the distance between them
#%$. a! b! c!
6opper is a paramagnetic materials ferromagnetic material diamagnetic material
#%/. ,witching on or off the current in one coil produces an emf in another coil adFacent to it. The two coils are said to have a! self inductance b! mutual inductance c! auto inductance #%4. The time constant in an inductive circuit is the time re'uired for the current to reach a! "%.2E of ma&imum value b! "%.$E of ma&imum value c! $0.$E of ma&imum value ##0. ,elf induced emf in a coil supplied with a current varying at a uniform rate can be found by a! ? @ d dt b! ? + d dt c! ? + d dt
Page 55
Module 3 – Electrical Fundamentals Sample Questions
##1. a! b! c!
The (() of a coil fed with 2 amps and having 10 turns is 5 ampere turns 20 ampere turns 20 amperes turn
##2. An A6 inductive circuit has an inductance of 10 m and a fre'uency input of 1000*. The opposition to current flow is appro&imately a! "%3000 ohms b! "%0 ohms c! "% ohms ##%. a! b! c!
A sine wave of ;(, value $.0$ volts has a pea to pea value of 10.0 volts 0.$0$ volts 20.0 volts
###. a! b! c!
The true power in an A6 circuit is given by voltmeter reading & 9) volts & amps volts & amps & 9)
##5. a! b! c!
The average value of 100 volts pea A6 is $0.$ volts 1#1.# volts "%.$ volts
##". a! b! c!
The ;(, value of 200 volts pea to pea is 1#1.# volts $0.$ volts 12$.# volts
##$. a! b! c!
The impedance of a series tuned circuit at resonance is *ero ma&imum minimum
##/. The copper loss on a single phase transformer is 25 Watts on full load. What will it be on half load a! 5 Watts b! 12.5 Watts c! ".25 Watts ##4. A transformer is designed to operate at "0 *. t is connected across a 50 * supply. The primary windings would a! draw more current b! draw less current c! draw the same current
Page 56
Module 3 – Electrical Fundamentals Sample Questions
#50. ;otating coil H through 40o will
a! increase the -() induced into H b! decrease the -() induced into H c! increase the -() induced into A #51. a! b! c!
A current transformer3 when disconnected from a circuit must be left open circuit short circuited have a resistor connected across the terminals
#52. What is the reflected impedance in the primary
a! 20 ohms b! 500 ohms c! 50 ohms #5%. a! b! c!
A transformer rated at a fre'uency of 200 * may be used at any other fre'uency may only be used at the rated fre'uency or above may only be used at the rated fre'uency or below
#5#. The dots are called3 and indicate
a! 'uadrature dots3 points are 40o out of phase b! phasing dots3 point that have the same polarity at the same moment in time c! phasing dots3 point that have the opposite polarity at the same moment in time
Page 57
Module 3 – Electrical Fundamentals Sample Questions
#55. a! b! c!
The power factor of an A6 circuit is the sine of the phase angle cosine of the phase angle tangent of the phase angle
#5". a! b! c!
The )orm )actor of an A6 waveform can be found by ;(, value divided by the average value average value divided by the ;(, value average value times the ;(, value
#5$. a! b! c!
A differentiator has a time constant which is long short e'ual to the input pulse
#5/. f the fre'uency is increased in an A6 circuit of pure resistance3 the effect is a! increased resistance b! decreased resistance c! nothing #54. A wire is rotated through a magnetic field. To give :6 it must be connected to a! a commutator b! slip rings c! a rectifier #"0. n an inductive resistive circuit3 1 amp flows from a supply of 100V dissipating 50 Watts of power. The phase angle is a! "0o b! 40o c! #5o #"1. a! b! c!
A transformer is built with a material having a narrow hysteresis loop wide hysteresis loop high coercive force
#"2. An alternator delivers 500V ;(, at 1 ampere. The power factor is 0./. The true power is a! 100VA b! #00W c! 500W #"%. A component that produces an output voltage due to incident light is called a a! li'uid crystal b! light emitting diode c! solar cell
Page 58
Module 3 – Electrical Fundamentals Sample Questions
#"#. n a circuit which possesses mutual inductance3 current is increased to the primary a! the induced -() in the secondary produces a current in the secondary circuit which opposes the increase in flu& due to the increase of current in the primary b! the induced -() in the secondary produces a current in the secondary circuit which assists the increase in flu& due to the increase of current in the primary c! the induced -() in the secondary produces a current in the secondary circuit whose flu& has no effect on the flu& in the primary #"5. a! b! c!
f the supply to a :6 shunt motor was reversed it would rotate in the opposite direction it would fail to run it would rotate in the same direction
#"". a! b! c!
,lip on a synchronous motor on start is 0E 50E 100E
#"$. a! b! c!
A shaded pole motor has shaded poles to increase efficiency create a rotating field reduce interference
#"/. A series motor draws a high current on start3 and then the current reduces. This is due to a! the resistance of the field and the armature in series b! the bac -() c! the resistance of the field and armature in parallel #"4. a! b! c!
Mn a brushless A6 generator3 the main rotating field is fed with A6 :6 via diodes on the rotor A6 from the rotating field e&citer
#$0. ,ingle phase components in a three phase system may be connected between a! phase A and H only b! phase and neutral only c! any phase and neutral M; between any two phases #$1. a! b! c!
nterpoles in a :6 generator are connected in parallel with the armature in series with the armature in series with the field
Page 5
Module 3 – Electrical Fundamentals Sample Questions
#$2. n a :6 generator3 the effect of armature reaction may be reduced by moving the brush gear a! from (@A to C@A b! in the direction of armature rotation towards the (@A c! against the direction of armature rotation towards the (@A #$%. a! b! c!
The windings embedded in the pole faces of a :6 generator are interpoles commutating coils compensating windings
#$#. a! b! c!
A " pole wave?wound generator has 2 brushes " brushes % brushes
#$5. a! b! c!
n a 2 phase induction motor the control winding is fed with variable phase A6 supply fi&ed A6 supply variable amplitude supply only
#$". A % phase induction motor can be reversed by a! isolating one phase b! reversing the rotor connections c! changing over any two phases #$$. a! b! c!
The speed of an A6 motor can be affected by the field current pairs of poles armature current
#$/. A generator rated at %0 >VA and power factor 0./ has a ma&imum continuous power output of a! %0 W b! 2# W c! %$.5 W #$4. An A6 motor which rotates at the same speed as the supply fre'uency is called a! a universal motor b! an induction motor c! a synchronous motor #/0. a! b! c!
An e&le of a paramagnetic material is iron silver glass
Page 6!
Module 3 – Electrical Fundamentals Sample Questions
#/1. n the circuit shown3 if the fre'uency is increased from *ero to resonant fre'uency3 the circuit current would
a! increase b! decrease c! stay the same #/2. The true power developed in this circuit is
a! 12W b! 50W c! 20W #/%. The filter shown is a
a! band stop filter b! low pass filter c! high pass filter
Page 61
Module 3 – Electrical Fundamentals Sample Questions
#/#. n the circuit shown3 impedance will be
a! 4 ohms b! 5 ohms c! $ ohms #/5. is a! b! c!
in a balanced Wheatstone bridge3 across the centre of the bridge there no current flow no voltage present at either end current and voltage at ma&imum
#/". A 2#V battery has an internal resistance of 1 ohm. When connected to a load3 12 amps flows. The value of the load is a! 12 ohms b! 1 ohm c! 12 ohm #/$. a! b! c!
The property of a material to accept lines of flu& is called permeability reluctance retentivity
#//. a! b! c!
Armature reaction in a :6 generator causes (@A to move in the direction of rotation (@A to move in the opposite direction of rotation C@A to move in the direction of rotation
#/4. a! b! c!
n a :6 motor3 H?-() rises if the motor speed rises speed falls load rises
#40. a! b! c!
Vibration in a magnet causes flu& to increase flu& to decrease flu& to stay the same
#41. a! b! c!
A high pass filter has high impedance to low fre'uency3 low impedance to high fre'uency high impedance to high fre'uency3 low impedance to low fre'uency high impedance to both high and low fre'uency
Page 62
Module 3 – Electrical Fundamentals Sample Questions
#42. What sort of wave would be used in a 6; oscilloscope to control sweep a! ,awtooth b! ,'uare c! ,ine wave #4%. f there was a mainly inductive load on an A6 generator3 the voltage with respect to the current would a! lead b! lag c! be in phase #4#. is a! b! c!
Mn a brushless A6 generator3 the permanent magnet generator output :6 A6 pulsed
#45. a! b! c!
The output from a rotating armature A6 generator would be taen from the rotor the stator either the rotor or the stator
#4". a! b! c!
A fre'uency wild A6 generator system has variable voltage and fre'uency variable fre'uency only variable voltage only
#4$. n a series +6; circuit at resonance3 ; = 100 ohms3 + and 6 are each 10 ohms. The total impedance is a! 100 ohms b! %0 ohms c! *ero ohms #4/. An A6 generator has four poles. To produce a fre'uency of #00* it must achieve a speed of a! "000 ;9( b! /000 ;9( c! 12000 ;9( #44. a! b! c!
f an A6 sinewave has an ;(, value of 5V its pea value is 1#.1# V ".%$ V $.0$ V
500. a! b! c!
The :aniel 6ell electrodes are copper and *inc carbon and *inc *inc and manganese dio&ide
Page 63
Module 3 – Electrical Fundamentals Sample Questions
501. An inductor of resistance 5 ohms and inductance 2m is connected to a :6 circuit. The time constant is a! #00 ns b! 10 seconds c! #0 ms 502. a! b! c!
The unit of flu& is the Weber Ampere turns Ampere turns metre
50%. The flu& density of a magnetic field is 1.5T. The length of the conductor in the field is 2 m and the speed of the conductor is 10 ms. The -() induced is a! 0.% V b! %0 V c! $.5 V 50#. A :6 generator armature has " poles and is lap wound. The number of brushes re'uired are a! " b! 2 c! % 505. ;eactive sparing is reduced by a! interpoles b! compensating windings c! au&iliary windings 50". a! b! c!
The bac -() in a :6 motor is e'ual to the applied -() less than the applied -() greater than the applied -()
50$. The flu& density of a magnetic field is 1.5T. The length of the conductor in the field is 2 m and the current flowing through the conductor is 5 amps. The force on the conductor is a! 15 @ewtons b! 0." @ewtons c! %.$5 @ewtons 50/. A :6 shunt motor has 2/ volts applied. The current taen from the armature of 2 ohms resistance is 1 amp. The H-() is a! %0 V b! 2$ V c! 2" V
Page 64
Module 3 – Electrical Fundamentals Sample Questions
504. a! b! c!
n a motor3 armature reaction causes the (@A to move in the direction of rotation against the direction of rotation to the C@A
510. a! b! c!
A circuit with good selectivity will have a large bandwidth a narrow bandwidth a low +6 ratio
511. a! b! c!
Apparent power in an A6 circuit is found by V& V & & cos V & & sin
512. a! b! c!
A %00 ohm resistor would have a colour code of orange3 orange3 brown orange3 brown3 blac orange3 blac brown
51%. a! b! c!
in a synchronous motor3 when the motor is running the slip is 100E 5E 0E
51#. a! b! c!
n a two?phase induction motor there are 2 poles % poles U c! # poles
515. The diagram shown is a
a! short shunt compound wound machine b! long shunt compound wound machine c! shunt wound machine
Page 65
Module 3 – Electrical Fundamentals Sample Questions
51". A transformer has 500 turns on the primary and 100 turns on the secondary. When connected to a 100 V supply3 the output is a! 500 V b! 20 V c! 25 V 51$. in the previous 'uestion3 the secondary is connected to a 10 ohm load. The primary current is a! 10 amps b! 0.# amps c! 2 amps 51/. a! b! c!
(agneto motive force can be found by @ &@ Hlv
514. a! b! c!
9ermeability of a material can be found by flu& density (() (() & flu& density (() flu& density
520. a! b! c!
A filter with a small bandwidth has a high value of O a low value of O a O of *ero
521. A transformer has 1200 turns primary and #/00 turns secondary. What value of load resistance would be re'uired to give a reflected impedance of 1000 ohms a! 1 ohm b! # ohm c! 1" ohm 522. a! b! c!
An autotransformer windings are on separate formers connected wired in parallel
52%. a! b! c!
What voltage can the neutral line carry in a star transformer 6ombined line voltages 8ero voltage 9hase voltage
52#. a! b! c!
in a generator system3 a stabili*ing winding is used in series with the field to prevent oscillations to prevent voltage overshoot to control output current
Page 66
Module 3 – Electrical Fundamentals Sample Questions
525. a! b! c!
When magneti*ing a piece of material3 magnetic strength will rise linearly with coercive force linearly with magnetic force non?linearly with magnetic force
52". a! b! c!
The stator of a permanent magnet rotor A6 generator is wound in series with the field is usually delta wound is usually star wound
52$. a! b! c!
n a resistiveinductive motor the resistor circuit must be disconnected after starting is less efficient than a capacitor start motor can only be used for light loads
52/. When a conductor is cut by magnetic lines of force an -() is induced. This is a! +en*Js +aw b! )aradayJs +aw c" >irchhoffJs +aw 524. a! b! c!
A #$> resistor has the following color code Sellow3 Violet3 Mrange Mrange3 Violet3 ;ed ;ed3 Mrange3 Sellow
5%0. a! b! c!
A material with a narrow hysterisis loop has a high retentivity has a low retentivity cannot be magnetised
5%1. The power output of a similar si*ed % phase compared to a single phase generator is a! less b! same c! more 5%2. a! b! c!
What part of a :6 motor would you find the poles brushes stator rotor
5%%. in a high O parallel resonant circuit3 what happens to impedance if capacitance is increased by a factor of # a! t reduces by $5E b! t remains the same c! t increases by factor of #
Page 67
Module 3 – Electrical Fundamentals Sample Questions
5%#. a! b! c!
n a thermocouple where is voltage measured At the hot Function At the cold Function At both Functions
5%5. a! b! c!
(ercury cells are covered with a metal cover as a protective cover as a positive terminal as a negative terminal
5%". When switching off the supply3 the bac emf in a collapsing field in an inductor a! never e&ceeds forward emf b! can be multiple times bigger than forward emf c! is e'ual to forward emf 5%$. f the energy supplied to a circuit for #hrs 15 mins at /00 Fsec what would be the energy consumed a! %.# >W rs b! %#00 >W rs c! %#0 >W rs 5%/. a! b! c!
A parallel circuit at resonance has its impedance at a ma&imum minimum *ero
5%4. a! b! c!
A parallel circuit with any number of 2 terminal connections has the same current throughout the individual voltage drops is e'ual to the emf the resistance is dependent on current
5#0. n this circuit3 ;& is e'ual to
a! ;% & ;2 L ;# b! ;% & ;# L ;2 c! ;2 & ;# L ;%
Page 68
Module 3 – Electrical Fundamentals Sample Questions
5#1. A transformer to supply a 2#V load with a 51 turnJs ratio will have what primary supply a! 120 V:6 b! #/ VA6 c! #./ V 5#2. a! b! c!
A material e&posed to heat will be harder to magnetise be easier to magnetise have no effect on magnetism
5#%. A 20 9ico farad capacitor with a 1(W resistor taes how long to charge a! 20 microseconds b! 0.1 second c! 100 microseconds 5##. A transformer has 2000V3 500 turns on the primary and 50 turns on the secondary. What would be the line voltage if the transformer were :elta,tar connected a! 200V b! %#"V c! #50V 5#5. The main advantage of a starter?generator over conventional units is a! for the same power output there is a weight reduction and the starter drive remains engaged b! for the same power output there is a weight reduction and the drive is constantly engaged c! it can produce a greater power output 5#". a! b! c!
The speed of a single phase induction motor is dependant on the strength of the field the number of pairs of poles the strength of the armature current
5#$. An A.6. shunt wound motor sometimes uses a volts dropping resistor. The resistor would be a! in series with the supply b! in series with the field c! in series with the armature 5#/. The time to fully charge a 1 micro farad capacitor in series with a 100> ohm resistor is a! 100 ms b! 10 ms c! c!1 ms
Page 6
Module 3 – Electrical Fundamentals Sample Questions
5#4. A sine wave has a periodic time of 0.5 milliseconds3 what is its fre'uency a! 200 * b! 2>h* c! 20>h* 550. a! b! c!
n a voltage e'uali*ing circuit the generators are regulated so the lower output is increased to that of the higher the higher output is decreased to that of the lower the lower is increased and the higher is decreased until they are e'ual
551. a! b! c!
The capacity of a battery is measured in volts cubic centimeters ampere?hours
552. 9hase angle is a! the difference in degrees of rotation between 2 alternating voltages or currents or a voltage and a current b! the difference in degrees between the positive and negative parts of an ac sine wave c! the cosine of the pea value of an ac voltage 55%. A batteryJs internal resistance is determined by a! ; = M6V 66V i b! ; = M6V G 66V i c! ; = M6V ? 66V V 55#. a! b! c!
The impedance of an ac circuit is measured in ilovolt?amperes amperes ohms
555. The formula for impedance in a series circuit is a! 8 = 7;2 G 7X6 X+ !2! b! 8 = 7;2 7X6 X+ !2! c! 8 = 7;2 7X6 G X+ !2! 55". (otor slip is a! the percentage of difference in speeds between the stator and rotor fields b! a shifting of the (@A of the motor c! a symptom of a wea field
Page 7!
Module 3 – Electrical Fundamentals Sample Questions
55$. a! b! c!
The principal characteristic of a synchronous motor is it rotates at a speed that is synchronised with the applied ac current it must have a synchronised % phase supply to operate it rotates at a speed that is synchronised with the applied dc current
55/. There are more negative than positive plates in a lead acid battery because a! the positive plates are prone to warping if the chemical action is taing place only on one side b! it reduces the internal resistance of the cell c! it is necessary for chemical action to tae place 554. a! b! c!
6ommutator ripple can be reduced by the use of a ripple filter increasing generator fre'uency a resistor in series with the armature
5"0. n this circuit applied voltage is
a! Vt = X6 b! Vt = X+ c! Vt = ; 5"1. a! b! c!
What is the internal resistance of a +eclanche cell " ohms ? 10 ohms 0.02 ohms ? # ohms 20 ohms ? %0 ohms
5"2. a! b! c!
n a :6 motor the interpoles are part of the field rotor assembly stator assembly
5"%. a! b! c!
The line voltage in a wye wound transformer is root % phase voltage the same as phase voltage root % & phase voltage
Page 71
Module 3 – Electrical Fundamentals Sample Questions
5"#. a! b! c!
The valence electron is the electron in outer shell of atom the electron in inner shell of atom a positive electron
5"5. An aircraft battery on charge from the aircraft generators causes a! internal resistance of the battery to decrease in sympathy with the decreasing charging current b! battery voltage to increases to nominal voltage and the charge current decreases c! battery voltage to decrease to *ero until it is fully charged 5"". a! b! c!
What happens to the current in a series resistive resonant circuit t is ma&imum t is minimum t is *ero
5"$. a! b! c!
An atom with a deficiency in electrons has high resistance low resistance high impendence
5"/. a! b! c!
What effect does hydrogen have in a battery cell 9olari*ation ,ulphation @othing
5"4. a! b! c!
-ddy current losses in a transformer are a! current used in magnetising the core current flow induced into the core hysteresis losses
5$0. a! b! c!
A %?phase star?delta wound transformer gives 40 phase shift no phase shift %0 phase shift
5$1. a! b! c!
n a parallel circuit containing resistors the voltage is the same in all parts of the circuit the sum of the voltage drops e'uals applied voltage resistance is determined by value of current flow
5$2. a! b! c!
An induced current in a coil opposes the -() producing it aids the -() producing it does not affect the -() producing it
Page 72
Module 3 – Electrical Fundamentals Sample Questions
5$%. a! b! c!
Armature reaction is reactive sparing due to dirty or worn commutator the (() opposing rotation
5$#. n a #1 step up transformer3 what would give a reflected impedance of 1> ohm a! 1 ohm b! # ohm c! 1" ohm 5$5. a! b! c!
+ines of magnetic flu& pass from @ to , - to W , to @
5$". a! b! c!
A shunt motor gives constant tor'ue with variations in speed is constant speed has high starting tor'ue
5$$. The direction of current in a wire rotating in a magnetic field can be determined by a! )lemingJs right hand rule b! )lemingJs left hand rule c! cor screw rule 5$/. The diagram shows a 200V long shunt generator. What is the voltage across the series resistor
a! %0V b! "V c! 10V 5$4. n a parallel +6; circuit3 if the capacitance is increased by # times3 what happens to the impendence a! increases by # times b! decreases by $5E c! remains the same
Page 73
Module 3 – Electrical Fundamentals Sample Questions
5/0. n a :6 shunt motor3 if the field resistance is increased what happens to the bac -() a! increases b! decreases c! remains the same 5/1. a! b! c!
Why is ferrite used in memory circuits igh remanence +ow permeability igh reluctance
5/2. a! b! c!
What semi?conductor material is used in memory circuits )errite 9ermeomag ron
5/%. a! b! c!
The discharge curve of a capacitor is +inear +ogarithmic -&ponential
5/#. a! b! c!
To generate electricity with a fuel cell3 you need a constant supply of M&ygen < ydrogen >erosene < eat @itrogen < ,unlight
5/5. )ive different value resistors all have the same voltage dropped across them3 how are the resistors connected a! n ,eries b! n 9arallel c! n ,eries9arallel 5/". The input is 115V and is applied across the %00 turn portion. What is the output
a! #"0V b! 115V c! 2/V
Page 74
Module 3 – Electrical Fundamentals Sample Questions
5/$. A near perfect #1 step up transformer has itJs primary connected to 120VA63 if the secondary is connected to a load with 1"00 ohms resistance what is the current in the primary a! 1 amp b! 0.% amps c! 1.2 amps 5//. a! b! c!
)lu& losses in a transformer can be prevented by the use of primary shielding winding the primary on top of the secondary laminating the core
5/4. a! b! c!
A ni?cad battery found to be below normal capacity should be removed and used for ground use only be re?charged with a freshening charge have its electrolyte adFusted
540. a! b! c!
n cold weather a battery must be ept fully charged fully discharged does not matter
541. a! b! c!
A simple basic induction motor has poor starting tor'ue3 good running tor'ue good starting tor'ue3 poor running tor'ue poor starting tor'ue3 poor running tor'ue
542. a! b! c!
f the fre'uency to a capacitor increases3 the current through it is *ero increases decreases
54%. a! b! c!
n a %?phase delta wound circuit3 line current is same as the phase current in phase with the phase current the vectorial sum of all % phase currents
54#. a! b! c!
6onductance of a circuit is 2 milli(hos. What is its resistance 5 (egaMhms 500 Mhms 5000 Mhms
545. a! b! c!
To increase the voltage output of a generator you can increase speed decrease speed t is not speed dependant
Page 75
Module 3 – Electrical Fundamentals Sample Questions
54". ow would you find the direction of the current flow in an armature located in a magnetic field a! (a&wells corscrew rule b! )lemings right hand rule c! )lemingJs left hand rule 54$. f in an electrical circuit there is a difference between the capacitive reactance and the inductive reactance3 what would the power factor of the circuit be a! Qnity b! +ess than unity c! (ore than unity 54/. a! b! c!
What is the , unit of conductance ,ieman Mhm Mhm?metre
544. a! b! c!
What is the , unit of resistivity Mhm metre Mhmsmetre Mhms
"00. a! b! c!
Cenerator voltage is dependant on speed of rotation independent of speed of rotation not dependant on speed of rotation
"01. a! b! c!
f a negatively charged conductor is placed ne&t to an insulated rod the rod has no charge the rod becomes negatively charged the rod becomes positively charged
"02. a! b! c!
What is the formula for conductance 1; 1?; ;G1
"0%. What happens if you reverse the supply to the field and armature of a :6 shunt motor a! ;everses direction of rotation b! 6ontinues to rotate in same direction c! )ails to start "0#. a! b! c!
The internal resistance of a battery off load compared to on load is same increased decreased
Page 76
Module 3 – Electrical Fundamentals Sample Questions
"05. a! b! c!
What is the rating of a monolithic capacitor with 10% on it 10000pf 100000pf 1000pf
"0". What is the formula for woring out the capacitance of a capacitor if > = dielectric constant3 A = area of the plates3 d = distance plates apart a! c = >Ad b! c = >dA c! c = d>A "0$. a! b! c!
115V ;(, 2.5A at "0 degrees what is the power disipated $4 W 1#% W %00 VA
"0/. a! b! c!
f cobalt has a permeability of #/00 it is a ferromagnetic paramagnetic diamagnetic
"04. a! b! c!
The output from a generator to a commutator is A6 :6 pulsed :6
"10. a! b! c!
When light hits a photodiode resistance increases decreases stays the same
"11. What type of wave is it when the vertical and hori*ontal distances are e'ual a! ,'uare b! ;ectangular c! ,awtooth "12. a! b! c!
6obalt has permeability greater than unity same as unity less than unity
"1%. a! b! c!
n an aircraft brushless alternator the armature is in series with the field star wound delta wound
Page 77
Module 3 – Electrical Fundamentals Sample Questions
"1#. To supply a 2# volt output with a transformer with a 51 turns ratio3 the input re'uired is a! 120V b! #./V c! 2#V "15. a! b! c!
in a resonant parallel circuit3 current is ma& min *ero
"1". a! b! c!
Total capacitance of % capacitors each 12m) in a parallel circuit %"m) 12m) "mf
"1$. a! b! c!
Hand stop filter attenuates fre'uencies in a specified narrow band stops fre'uencies in a narrow band pass all fre'uencies in that band
"1/. A combination of 1 megohm and / microfarad would give a time constant of a! #0 seconds b! / seconds c! #00 ms "14. a! b! c!
9ower factor is sin theta cos theta tan theta
"20. a! b! c!
What is the main disadvantage of a starter generator Will not supply output at low rpm eavier than lie for lie 6an only be used on piston engines
"21. a! b! c!
What is the voltage across a fully charged capacitor ,ame as circuit voltage +ess than circuit voltage (ore than circuit voltage
"22. a! b! c!
When would you use an electrolytic capacitor Mn a balanced circuit +arge output compared to si*e re'uired +ow output compared to si*e re'uired
Page 78
Module 3 – Electrical Fundamentals Sample Questions
"2%. f the phase voltage of a star wound generator is 115V3 what would be the line?to?line voltage a! 200V b! 1/0V c! 220V "2#. a! b! c!
Hac?-() is the greatest when a motor is at operating speed Fust starting to rotate under heavy load
"25. a! b! c!
What are the factors affecting the fre'uency of an ac generator @umber of turns in the armature coil and rpm @umber of pole pairs and rpm @umber of turns in the armature coil and number of pole pairs
"2". Which of the following applications would re'uire a Ycontinuously ratedY motor a! )lap drive actuator b! )uel pump motor c! 6argo door actuator "2$. a! b! c!
What would you use for the core in a generator current transformer Air core +aminated core ,teel 6ore
"2/. a! b! c!
,pontaneous magnetisation occurs in a permomagnet ferromagnet diamagnet
"24. An aircraft transformer is needed to step up a voltage. What sort would be used a! Air core b! +aminated core c! ,olid core "%0. a! b! c!
A conductor is placed in a magneti*ed coil. What will happen A force will be created @othing will happen unless the conductor is moved The conductor will move
"%1. a! b! c!
An atom with less than # electrons in its outer shell has low electrical resistance high electrical resistance no electrical resistance
Page 7
Module 3 – Electrical Fundamentals Sample Questions
"%2. n a #1 step?up transformer3 120V is applied to the primary3 and the load on the secondary is 1"00 Mhms. What is the current in the primary a! 0.0$5A b! 1.2A c! %A "%%. a! b! c!
Two 12V3 #0Ah cells in series gives 2#V #0Ah 2#V /0Ah 12V #0Ah
"%#. a! b! c!
A 2 (egohm resistor can be written (20) 2(0) 20()
"%5. f a resistor is too small or misshapen to fit the colour code bands3 how else is itJs value indicated a! :ots b! +etter code c! @umber code "%". -lements such as phosphorus with 5 electrons in their outer shell3 when combined with pure silicon3 is a a! donor b! acceptor c! isotopic "%$. This is a diagram of a
a! +ight :ependant ;esistor b! +ogarithmic :ifferential ;esistor c! +aser :iode ;ectifier "%/. a! b! c!
A centrifugal speed switch is used to cut out the resistorinductor circuit on an A6 motor to cut out the capacitor circuit on an A6 motor to cut in the resistorinductor circuit on an A6 motor
"%4. :isconnecting one of the phases from a %?phase motor will cause the motor to a! stop b! run a 2% speed c! run at the same speed
Page 8!
Module 3 – Electrical Fundamentals Sample Questions
"#0. a! b! c!
To find the internal resistance of a battery in a circuit of nown current use the formula ; = V & find the lost volts of the circuit find the -() of the circuit
"#1. a! b! c!
A capacitor has Hrown Hlac Mrange bands. tJs value is 10 picofarads 10 nanofarads 100 picofarads
"#2. a! b! c!
ydrogen atom consist of 9roton3 @eutron and -lectron 9roton and -lectron only @eutron and proton only
"#%. a! b! c!
A generator with more than two phases is nown as polyphase delta phase multiphase
"##. a! b! c!
(agnetic lines are flowing parallel they will repel each other attract each other have no effect on each other
"#5. a! b! c!
(agnetic flu& is more concentrated at the centre of bar magnet occupies the space around the magnet with e'ual flu& density e&ist in all space around the magnet
"#". a! b! c!
n electrical circuit3 direct current power in represented by Ampere Watt Boules
"#$. a! b! c!
n ,.. units3 wor is denoted by @ewton?meter which is Boules >ilogram?force?metersec which is (etric orsepower Boulessec which is Watts
"#/. When a conductor carrying a current and placed in a magnetic field it e&periences a! an electrostatic force b! an electromagnetic force c! a magnetic force "#4. a! b! c!
9ea factor in A6 circuit. 1.#1# times ma&. value of applied voltage 1.11 times ma&. value of applied voltage 0.$0$ time ma&. value of applied voltage Page 81
Module 3 – Electrical Fundamentals Sample Questions
"50. felt at a! b! c!
The hori*ontal component of the earthJs magnetic field is most strongly poles e'uator #5 degrees latitude
"51. This is a diagram of a
a! Variable Voltage source b! Variable ;esistor c! Variable 6urrent source "52. )ind voltage at point YHY
a! 10V b! $V c! 2"V "5%. a! b! c!
Voltage measured between the plates of a capacitor will be same as applied voltage less than applied voltage can dangerously higher than applied voltage
"5#. n a ,eries +6 circuit if the value of the capacitance is increased then the power factor will be a! greater than 1 b! e'ual to 1 c! less than 1 "55. A heater which consumes /00 >iloFoulessec is on for #hrs 15min. The power consumed is a! %#00 Wh b! %.# Wh c! %#0 Wh
Page 82
Module 3 – Electrical Fundamentals Sample Questions
"5". A 10V battery supplies a resistive load of 10 ohms for 1 minute. What is the power supplied a! 100W b! 10VA c! 10W "5$. a! b! c!
A 2#V #0A battery discharges at 200mA. ow long will it last 200 hours %00 hours #00 hours
"5/. a! b! c!
n a Wheatstone bridge at balance the galvanometer reads *ero volts amps ohms
"54. 1 Volt is produced when a current of 1 Amp per second is varied in a coil ? this is a definition of a! 1 enry b! 1 6oulomb per second c! 1 Ampere per meter ""0. A generator supplies 150VA6 phase and load is 10 Mhms per phase ? what is the phase current a! 15 A b! 1.5 A c! 25.5 A ""1. a! b! c!
Hand pass filter in a circuit allows fre'uencies above a cut?off fre'uency to pass allows fre'uencies below a cut?off fre'uency to pass only allows a narrow band of fre'uency to pass
""2. a! b! c!
-ddy current losses is due to resistant of the copper conductors used in windings flowing in transformer core caused by induced V magnetic flu& produced by primary winding not lining with secondary winding
""%. The ability of a circuit to produce a magnetic flu& under the influence of a (() a! permeability b! permeance c! permanence ""#. Two inductor coils in very close pro&imityP if one of the coils is rotated 40 degrees slowly away from the other the mutual inductance a! increases b! decreases c! remains the same Page 83
Module 3 – Electrical Fundamentals Sample Questions
""5. a! b! c!
(agnetic flu& saturation taes place when the magnetised medium will accept no further lines of flu& the magnetic field starts to reduce with increased magnetising force the magnetic field drops to *ero
""". a! b! c!
:ielectric constant of a capacitor is electrostatic storing capability of the dielectric ma& stored in the capacitor ma& V that can be applied to a capacitor
""$. a! b! c!
The type of motor used in a linear actuator is compound series parallel 7shunt wound!
""/. a! b! c!
The phases on a three phase a.c generator are spaced at 40 degrees 1/0 degrees 120 degrees
""4. a! b! c!
The controlling wave in a 6;T is sinusoidal s'uare sawtooth
"$0. f the speed of a coil in a magnetic field is doubled and the field strength is doubled the output will a! half b! stay the same c! 'uadruple "$1. a! b! c!
A wave form having e'ual amplitude and time base is a s'uare waveform sawtooth rectangular
"$2. a! b! c!
An inductor is said to be saturated when the current is at a ma&imum it will no longer accept lines of flu& the current through it is *ero
"$%. a! b! c!
The controlling phase on a two phase generator is of a fi&ed amplitude variable amplitude direct current
"$#. a! b! c!
ow many brushes are used in an / pole wave wound machine 2 " / Page 84
Module 3 – Electrical Fundamentals Sample Questions
"$5. a! b! c!
A high pass filter consists of a capacitor and inductor in series capacitor and inductor in parallel an inductor and a capacitor in parallel
"$". a! b! c!
)or an atom to become a negative ion it must gain at least one electron lose at least one electron have undergone ionisation by the sun
"$$. a! b! c!
What is the ma&imum number of electrons in shell ( of an atom " 1" 1/
"$/. a! b! c!
A neutral atom with an atomic no. of % has how many electrons 1 % :ependant on type of atom
"$4. a! b! c!
The nucleus of an atom is Gve charged neutral ?ve charged
"/0. a! b! c!
-lectron orbits are called shells waves valences
"/1. a! b! c!
The unit of energy is the Watt Boule 6oulomb
"/2. a! b! c!
9otential difference is another term for energy voltage charge
"/%. a! b! c!
The electrolyte level of a ni?cad battery falls during discharge falls during charge rises during discharge
"/#. a! b! c!
A thermocouple is basically a type of milliammeter millivoltmeter miliohmeter
Page 85
Module 3 – Electrical Fundamentals Sample Questions
"/5. a! b! c!
X+ is the symbol of inductive reactance capacitive reactance impedance
"/". a! b! c!
n the shunt generator the field is supplied by a separate supply the armature the load
"/$. a! b! c!
ncreasing the speed of an aircraft generator results in an automa field circuit resistance increase field circuit resistance decrease armature circuit resistance increase
"//. a! b! c!
Which generators are usually used on aircraft ,eries ,hunt 6ompound
"/4. a! b! c!
n a cumulative compound wound generator the the series and shunt fields oppose each other the series and shunt fields assist each other the voltage falls suddenly with an increase in load
"40. a! b! c!
The shunt wound generator is controlled by a variable resistance in series with the armature series with the field parallel with the field
"41. a! b! c!
ncreasing the load on a permanent magnet generator will reduce the terminal voltage by a large amount reduce the terminal voltage by a small amount increase the terminal voltage by a small amount
"42. The series wound generatorJs terminal voltage will3 when below saturation a! increase with an increase in load b! decrease with an increase in load c! decrease with a decrease in rotational speed "4%. a! b! c!
The shunt wound generator is normally started off load on load -ither of the above
Page 86
Module 3 – Electrical Fundamentals Sample Questions
"4#. Two % phase generators operating in parallel with different phase and line voltages will be connected in a! star configuration b! delta configuration c! 9arallel configuration "45. a! b! c!
-&tra windings in a % phase A6 generator are to sense overvolt phase shift field oscillations
"4". 6ables are shielded to prevent YY magnetic interference in wires with the following material a! 6opper braiding b! )erromagnetic material c! :iamagnetic material "4$. a! b! c!
Qsing MhmJs law current is directly proportional to the -() resistance is directly proportional to -() current is directly proportional to the resistance
"4/. A 101 step up power transformer has 120 V3 and %A flowing through the primary3 and 0.2/5 A flowing through the secondary what is the efficiency a! 40E b! 45E c! /5E "44. a! b! c!
When light energises a component3 what is the component 9hotodiode +a*erdiode +ight emitting diode
$00. a! b! c!
:elta wound alternator currents are the same as line current the same as phase current the phase current multiplied be the s'uare root of %
$01. a! b! c!
Aircraft autotransformers are of what type Mpen core Twin core +aminated core
$02. a! b! c!
n a series circuit with % resistors3 the current is lower than the smallest even in all % the total of all % using ohms law to find the current
Page 87
Module 3 – Electrical Fundamentals Sample Questions
$0%%. $0 a! b! c!
An o&yg &ygen ato atom has has electr electrons ons33 neutron neutronss and proto protons ns proton protonss and and elect electron ronss only only proton protonss and and ne neutr utrons ons only only
$0#.. What $0# What is the the volt voltage age dropp dropped ed aacro cross ss res resist istor or JAJ JAJ
a! 2 V b! 10 V c! 20 V $05.. What $05 What is is the the curren currentt thro through ugh resist resistor or 6
a! 4A b! #.5A c! 1/A $0". Mne volt volt is induced induced into into a circuit circuit with with a current current varying varying at 1 amp per second. The circuit has a! 1 enry b! 1 am ampe pere re turn turn c! 1 Tesla
Page 88
Module 3 – Electrical Fundamentals Sample Questions
$0$. ow do $0$. do you you reduce reduce ripp ripple le on the the outpu outputt of a :6 gene generat rator or a! ncrease ncrease the the speed speed of the the armature armature and and ad addd more turns b! ncrease ncrease the commutat commutator or segments segments and and connect connect each to a separa separate te parallel winding c! :ecrease :ecrease the the speed speed of the armatur armaturee and add add more series series winding windingss $0/. ;esistors ;esistors re'uire re'uiredd to carry carry a comparativ comparatively ely high high current current and dissip dissipate ate high power are usually of a! 6arbon 6arbon compou compound nd type type b! Wire Wire woun woundd meta metall type type c! Wire Wire woun woundd cera ceramic mic type type $04. The prope property rty of a conducto conductorr of electri electricity city that limits limits or restricts restricts the flow flow of electric current is a! limiter b! fuse c! resi resist staanc ncee $10. a! b! c!
Armature Armature reactio reactionn cause causess neutra neutrall a&is a&is to shift shift in the the direct direction ion opposite oppo site to to the direction direction of of armature armature rotatio rotationn in the dire directi ction on of armat armature ure rotat rotation ion either 7a! or or 7b! depe depending nding on curren currentt flo flow w
$111. $1 a! b! c!
9ote 9otent ntio iome mete ters rs are are fi&ed varia ariabl blee adFu ad Fust staable ble
$12. $1 2. a! b! c!
>irc >irchh hhof offJfJss law law is app applic licab able le to to para pa ralle llell net netwo wor rss clos closed ed lloo oopp netw networ ors s seri se ries es net netw wors ors
$1%. $1 %. a! b! c!
Whic Whichh is no nott ther therma mallllyy ope opera rate ted d curr cu rren entt limit limiter er fuse limit limitin ingg resi resist stor or
$1#. What is the current current in the circuit circuit with a resistanc resistancee of / ohms3 inductive inductive reactance of 12 ohms3 capacitive reactance of 1/ ohms with 20 volts applied across it a! 2 amps b! 1 amp c! 10 amps $15. )ormation )ormation of white white crys crystals tals of of potassi potassium um carbon carbonate ate on on a properly properly serviced @i?cd battery indicates a! full full ch char arge gedd b! un unde derr cha charg rged ed c! ov oveer cha charg rged ed Page 8
Module 3 – Electrical Fundamentals Sample Questions
$1". $1 ". a! b! c!
Ther Therma mall runa runaw way cau cause sess viol violen entt ga gass ssin ingg boiling boiling of electroly electrolyte te and melting melting of plates plates and and casing casing both bo th 7a! 7a! and and 7b! 7b!
$1$. n smaller smaller single single or twin engine engine aircraf aircraftt the primary primary :6 power power is supplied in the form of rectified output from a! fre'ue fre'uency ncy wild wild ac gene generat rator or b! un unde derr cha charg rged ed c! ov oveer cha charg rged ed $1/. $1 /. a! b! c!
The The uni unitt for for resi resist stiv ivitityy ohms oh mss s'u 'uar aree met meter er ohmm mmeeter ohms oh msme mete ter r
$14. $1 4. a! b! c!
An au auto to tran transf sfor orme merr is is primar primaryy and and secon secondar daryy coils coils primary primary and secondary secondary coils on ssingle ingle bar prim primar aryy coi coill only only
$20. $2 0. a! b! c!
A ne neut utra rall atom atom gai gains ns ele elect ctro rons ns.. t gain gainss a po posit sitive ive ch charg argee t rema remain inss neu neutra trall t gain gainss a ne negat gative ive ch charg argee
$211. $2 a! b! c!
An o&yg &ygen ato atom has has proton protons3 s3 neutro neutrons ns and elec electro trons ns neut ne utro rons ns and and pro proto tons ns prot proton onss and and elec electro trons ns
$22. $2 2. a! b! c!
The The , , uni unitt of of wor wor is is the the Watt @ew @ewton ton (e (ete ter r Boule
$2%. $2 %. a! b! c!
Two para parallllel el lin lines es of of magn magnet etic ic flu flu&& attr attrac actt each each othe otherr repe repell eac eachh othe other r have have no eff effect ect on eac eachh other other
$2##. $2 a! b! c!
Mne Mne mi micr croo fara faradd is 12 1 & 10 farads 1 & 10 ?" farads 1 & 10 ?12 farads
$25. $25. a! b! c!
,ponta ,pontaneo neous us mag magnet netism ism is associ associate atedd with with ferrom ferromagn agneti eticc mat materia erials ls diamag diamagnet netic ic mat materi erials als para pa rama magn gnet etic ic mater materia ials ls Page !
Module 3 – Electrical Fundamentals Sample Questions
$2". The difference in speed between a synchronous motorJs rotor and stator is nown as a! phase lag b! slip speed c! rotor lag $2$. a! b! c!
A voltage of 250V causes a current of %0mA. What is the wattage 0.225W $.5W $500W
$2/. a! b! c!
The -() of a generator can be calculated from which law +en*s law >irchhoffJs law )aradays law
$24. a! b! c!
The windings on a autotransformer are wound on separate legs of core wound with the primary over the secondary wound with no magnetic core
$%0. a! b! c!
A primary cell can be recharged can not recharged can be recharged but only a few times
$%1. a! b! c!
f the insulation resistance of a leadacid battery is down it indicates intercell leaage case leaage leaage between positive and negative terminals
$%2. a! b! c!
An indication of good commutation on a :6 machine would be silent operation of the machine little or no sparing at the commutator high armature currents
$%%. ,ingle phase components in a % phase system may be connected between a! phase A and H only b! any phase and earth c! any phase and earth or between any two phases $%#. a! b! c!
Qnder fre'uency in an A6 supply would cause overheating of inductive devices overspeeding of A6 motors overvoltage of capacitive devices
Page 1
Module 3 – Electrical Fundamentals Sample Questions
$%5. a! b! c!
The line voltage of a % phase star connected A6 generator is less than the phase voltage greater than the phase voltage e'ual to the phase voltage
$%". n an A6 generator of the brushless type the rotating field winding is fed with a! :6 via the slip rings from an e&ternal supply b! :6 via diodes from the main e&citer winding on the rotor c! A6 via rotating e&citer windings $%$. An A6 generator is rated at %0 VA at 0./ 9ower )actor this means that the ma& continuous output should not e&ceed a! %0 >W b! %$.5 >W c! 2# >W $%/. To adFust the voltage of an A6 generator3 whilst maintaining constant fre'uency3 it is necessary to a! alter the driving speed b! alter the field current c! alter the reactance of the starter winding circuit $%4. a! b! c!
f compound :6 generators are operated in parallel they must all rotate at the same speed have an e'uilising or load sharing loop all use the same voltage
$#0. a! b! c!
The windings embedded in the pole faces of a generator are interpoles commutating 6oils compensating 6oils
$#1. a! b! c!
The ,ine wave signals of a circular time base are phase separated by 40o phase separated by 1/0o in phase
$#2. a! b! c!
n a :elta connecte the line current is 1.$ X phase 1.$ X phase V phase
$#%. a! b! c!
n a :esynn indicator system3 the rotor is a permanent magnet an electromagnet an A6 magnet
Page 2
Module 3 – Electrical Fundamentals Sample Questions
$##. a! b! c!
What is the purpose of the capacitor used in a single phase A6 motor ,moothing 6hanging direction of motor 9rovides a high starting tor'ue
$#5. a! b! c!
A thyristor has a positive temperature coefficient if energi*ed on3 will switch on a circuit if energi*ed on3 will switch off a circuit
$#". A circuit with a capacitor has " volts applied to it with a charge of 2#00 9ico?coulombs. What would the charge be if the applied voltage was 1.5 volts a! 2#00 & 10?12 coulombs b! "00 & 10?4 coulombs c! "00 & 10?12 coulombs $#$. A circuit containing a resistor3 capacitor and inductor where resonant fre'uency is met3 what will the impedance of the circuit be a! *ero b! resistance across the resistor c! ma&imum $#/. The temperature of a pure metal can greatly affect the resistance of it. What temp scale is used a! 6entigrade b! )ahrenheit c! Absolute $#4. first a! b! c!
When battery connected to the aircraft3 which terminal should connect Gve ?ve any
$50. a! b! c!
A differentiator has a time constant that will give a long pulse a short pulse an e'ual pulse
$51. first a! b! c!
When battery connected to the aircraft3 which terminal should connect Gve ?ve t maes no difference3 provided the master switch is off
Page 3
Module 3 – Electrical Fundamentals Sample Questions
$52. An ammeter in a battery charging system is for the purpose of indicating the a! amperage available for use b! total amperes being used in the aeroplane c! rate of current used to charge the battery $5%. The ma&imum output voltage from a basic single loop generator is when the loop is a! cutting ma&imum lines of magnetic flu& b! rotating anti ?clocwise relative to the direction of the magnetic flu& c" at #5o to the magnetic flu& $5#. a! b! c!
9rolonged reactive sparing in a :6 generator could damage the commutator armature pole pieces
$55. a! b! c!
The poles of a d.c generator are laminated to reduce hysterisis losses reduce flu& losses reduce eddy current losses
$5". Which re'uires the most electrical power during operation a! A 12?volt motor re'uiring / amperes b! )our %0?watt lamps in a 12?volt parallel circuit c" Two lights re'uiring % amperes each in a 2#?volt parallel system $5$. a! b! c!
A #$> Mhm resistor with a 10E tolerance has the following color code Sellow3 Violet3 Mrange3 ,ilver Mrange3 Violet3 ;ed3 Cold ;ed3 Mrange3 Sellow3 ,ilver
$5/. a! b! c!
)or how many hours will a 1#0A battery deliver 15A 15.15 hours 4.%% hours 2$.25 hours
$54. a! b! c!
What part of a nicel?cadmium cell helps to prevent thermal runaway The positive plate The negative plate The separator
$"0. When charging current is applied to a nicel?cadmium battery3 the cells emit gas only a! toward the end of the charging cycle b! when the electrolyte level is low c! if the cells are defective
Page 4
Module 3 – Electrical Fundamentals Sample Questions
$"1. a! b! c!
n a capacitor3 the dielectric strength is measured in Volts per metre 6oulombs per m2 )arads per meter
$"2. Three capacitors connected in series3 each having a value of 12 picofarads3 calculate the total capacitance. a! %" picofarads b! 12 picofarads c! # picofarads $"%. (agnetic fields around two parallel conductors carrying current in the same directions will a! attract b! repel c! will attract or repel depending on the type of current $"#. a! b! c!
(agnetic field on a solenoid is strongest outside the coil weaest outside the coil the same both inside and outside the coil
$"5. ow does one reduce ysteresis loss of a transformer a! Wind the coils one over the other and by careful design of the transformer b! Hy using a core material which can be easily demagneti*ed c! Hy laminating the core $"". a! b! c!
What is the power factor in a purely resistive circuit Creater than 1 +ess than 1 but greater than *ero -'ual to 1
$"$. a! b! c!
Mne advantage of a :6 motor over an A6 motor is the :6 motor will use less current the direction of rotation of the rotor can be changed less voltage is re'uired in :6 than A6
$"/. A load that is subFect to a potential difference with a current running through it will a! dissipate power in the form of heat b! have a magnetic field around it with the magnitude and direction of the field determined by the corscrew rule c! will move in a $"4. a! b! c!
n a shunt wound direct current independent of load propotional to the current in the armature inversely proportional to the current in the armature
Page 5
