practice set

SSC JE ELECTRICAL PRACTICE SET - 6

1.
 Generally an electrolytic capacitor is made to provide  _________ . A Fixed capacitance B Variable capacitance C Low capacitance D Large value of capacitance Answer : D Explanation :
2.
 Voltage applied across a ceramic dielectric produces an electrostatic field  100 times greater than in air. The dielectric constant of the ceramic equals  _________ A 100/3 B 50 C 100 D 1/100 Answer : C Explanation :
3.
 Which of the following capacitors of identical rating will have the smallest dimensions A Ceramic capacitor B Mica capacitor C Aluminium foil capacitor D Paper capacitor Answer : A Explanation :
4.
 Internal heating of capacitor is usually attributed to  _________ . A Dielectric charge B Plate vibration C Electron movement D Leakage resistance Answer : D Explanation :
5.
 During discharge of a battery A The voltage of cell decreases B The voltage of cell increases C Voltage does not change D None of these Answer : A Explanation :
6.
 Which efficiency of the battery is more A Watt hour efficiency B Ampere hour efficiency C Overall efficiency D None of these Answer : B Explanation :
7.
 If three  30μF  capacitors are connected in series, the net capacitance is  _________ A 10μF B 60μF C 90μF D None of these Answer : A Explanation :
8.
 For making capacitors, it is better to select a dielectric having  _________ A High permittivity B Low permittivity C Permittivity same as that of air D None of these Answer : A Explanation :
9.
 The materials having low retentivity are suitable for making A Temporary magnets B Permanent magnets C Weak magnets D None of these Answer : A Explanation :
10.
 In a parallel circuit operating with a source of  30 V  AC, designed to carry a total current of  6A, what happens to the protection device (fuse) when the resistance suddenly change to  2 Ω A It closes B There is no change C It shorts to ground D It opens Answer : D Explanation :
11.
 Which of the following determines total power in a series circuit A Source voltage times the current B Total voltage applied to the circuit C Current flowing through a switch D Average of the wattage consumed by each resistor Answer : A Explanation :
12.
 What should be observed when connecting a voltmeter into a DC circuit A RMS B Resistance C Polarity D Power factor Answer : C Explanation :
13.
 A potential divider is normally connected  _________ A Outside the generator circuit towards the loads circuit B Within the generator circuit C At a distance  V/100  metres from the generator where V is the voltage to be measured in KV D None of these Answer : A Explanation :
14.
 In a pure inductive circuit  __________ A The current leads applied voltage by  90 degree B The current is in phase with applied voltage C The current lags applied voltage by 90 degree D None of these Answer : C Explanation :
15.
 The average power in a pure inductive circuit is  _________ A 0 B VIU C VI cos 𝛷 D $\sqrt{3}$ VI cos 𝛷 Answer : A Explanation :
16.
 In a R-L series circuit the power factor  P.F.  is  _________ A Leading B Lagging C 0 D 1 Answer : B Explanation :
17.
 The angle of a series  R-L-C  circuit is leading if  __________ A XL = 0 B R = 0 C XC > XL D XC < XL Answer : C Explanation :
18.
 In an R-L-C  series circuit, during resonance,  the impedance will be A Zero B Minimum C Maximum D None of these Answer : B Explanation :
19.
 Kirchhoff’s current law (KCL) is applicable only to  _________ A Closed loops in a network B Electronic circuits C Junction in a network D Electric circuits Answer : C Explanation :
20.
 Flow of electrons in the circuit constitutes  __________ A Magnetic charge B An emf C An electric current D None of these Answer : C Explanation :
21.
 The material used for the magnetic circuit where high value of flux density required is  __________ A Cast iron B Ferro cobalt C Soft steel D Gray cast iron Answer : B Explanation :
22.
 If two resistance of  10Ω  are connected in parallel the equivalent is  ___________ A 15 Ω B 100 Ω C 5 Ω D 1 Ω Answer : C Explanation :
23.
 Unit of magnetic flux is A Weber B Ampere-turn C Weber/m2 D Coulomb Answer : A Explanation :
24.
 Fleming’s hand rule is used to find  __________ A Polarity of magnetic pole B Direction of flux in a solenoid C Direction of magnetic field due to current carrying conductor in a magnetic field D Direction of force on a current carrying conductor in a magnetic field Answer : D Explanation :
25.
 In which of the following voltage source is the movement of conductors in a magnetic field used to produce voltage A In a thermos couple B In a zinc copper element C In a DC generator D In a transformer Answer : C Explanation :
26.
 The relative permeability of a material is  0.95. the material is  __________ A Diamagnetic B Paramagnetic C Ferromagnetic D None of these Answer : A Explanation :
27.
 The series magnet of a single phase Energy mater consists of coil of  ___________ A Thin wire of few turns B Thick wire of few turns C Thick wire of more turns D Thin wire of more turns Answer : B Explanation :
28.
 The relative paramagnetic of paramagnetic material is  __________  ? A Less than unity B Equal to unity C Greater than unity D None of these Answer : C Explanation :
29.
 Reluctance offered by the magnetic circuit depends upon  __________ A Nature of magnetic material B Length of magnetic flux path C Cross-sectional area of the material D All options are correct Answer : D Explanation :
30.
 Magnetic recording tape is most commonly made from  ___________ A Small particles of iron B Silicon-iron C Ferric oxide D None of these Answer : C Explanation :
31.
 Moving iron meters can be used to measure  __________ A Both  AC and DC B Only AC C Only DC D None of these Answer : A Explanation :
32.
 A network has  10 nodes and 17 branches. The number of different node pair voltage would be A 7 B 9 C 45 D 10 Answer : C Explanation :
33.
 Which  one of the following is applicable to  any network linear or non-linear, active or passive, time varying or invariant as long as Kirchhoff’s laws are not violated A Tellegen’s  theorem B Reciprocity theorem C Maximum power transfer theorem D Superposition theorem Answer : A Explanation :
34.
 In Which  one of the following, it is not desired to attain the condition of maximum power transfer A Electronic circuits B Communicational circuits C Computer circuits D Electric circuits Answer : D Explanation :
35.
 A current mirror can be used as an active load because A It has low  AC  resistance B It has high  AC  resistance C It has high  DC  resistance D It has low  DC  resistance Answer : B Explanation :
36.
 If the capacitor of a single phase motor is short circuited, the motor will  ___________ A Start B No Start C Start with jerks D Start and then stop Answer : B Explanation :
37.
 The speed of the rotating magnetic field in an induction motor is known as the A Slip speed B Effective speed C Shaft speed D Synchronous speed Answer : D Explanation :
38.
 Which  one of the following is essential for the reciprocity theorem to be applicable A Linearity B Bilateralism C No initial history D All options are correct Answer : D Explanation :
39.
 When the frequency of the rotor of an induction motor is small, it can be measured by  ____________ A Galvanometer B DC moving coil milli- voltmeter C DC moving coil ammeter D AC voltmeter Answer : B Explanation :
40.
 The value of the capacitor in a capacitor start motor controls the A Starting torque B Speed of the motor C Efficiency D None of these Answer : A Explanation :
41.
 Which  one of the following is most economical method for starting single-phase motor A Capacitor start method B Split-phase method C Induction-start method D Resistance start method Answer : A Explanation :
42.
 Which  one of the following motors is represented by the characteristics curve shown below  Figure A DC shunt motor B DC series motor C DC compound motor D Asynchronous motor Answer : D Explanation :
43.
 For a 100% efficient transformer, the primary winding has 1000 turns and the secondary 100 turns. If the power input to the above transformer is  1000 watts, the power output is  __________ A 1000 watts B 100 watts C 10 watts D 10 bk W Answer : A Explanation :
44.
 What is the efficiency of transformer compared with that of electrical motors of the same power A Much smaller B Somewhat smaller C About same D Much higher Answer : D Explanation :
45.
 In a common emitter amplifier, the un bypassed emitter provides  __________ A Voltage-shunt feedback B Current series feedback C Negative-voltage feedback D Positive-voltage feedback Answer : C Explanation :
46.
 Which input yields natural response A Step input B Sinusoidal input C Impulse input D Ramp input Answer : C Explanation :
47.
 The voltage of a circuit is measured by a voltmeter having input impedance comparable with the output impedance of the circuit thereby causing error in voltage measurement. This error may be called as  ________ A Gross error B Random error C Error caused by misuse of instrument D Error caused by loading effect Answer : D Explanation :
48.
 Which  one of the following options is an Active transducer A Photo emissive cell B Photo voltaic cell C Selsyn D Photo emissive cell, photo voltaic cell another selsyn Answer : B Explanation :
49.
 Un-bonded strain gauges are  ________ A Exclusively used for transducer applications B Exclusively used for stress analysis C Used for unbounded strains only D None of these Answer : A Explanation :
50.
 Dynamometer type moving coil instrument are provided with  _______ A Eddy current damping B Pneumatic damping C Fluid friction damping D Electrostatic damping Answer : B Explanation :
51.
 Voltmeter is a galvanometer with  _________ A High resistance B Low resistance C Both low and high resistance D Uncertain resistance Answer : A Explanation :
52.
 Strain gauge rosettes are used when  __________ A The direction of hoop stress is not known B The direction of principal stress is not known C The direction of principal stress is known D The direction of longitudinal stress is not known Answer : B Explanation :
53.
 The dead time of an instrument refers to  ________ A Large change of input quantity for which there is no output B The time encountered when the instrument has to wait for some reactions to take place C The time before the instrument beings response  after the quantity has altered D Retardation or delay in the response of a instrument to a change in the input signal Answer : C Explanation :
54.
 One input terminal of high gain comparator circuit is grounded and a sinusoidal voltage is applied to the other input. The output comparator will be  _________ A A sinusoidal B A full rectified sinusoidal C A half rectified sinusoidal D A square wave Answer : D Explanation :
55.
 A minimum phase system with no zeros has angle of  –2700  at gain crossover frequency. The system is A Stable B Unstable C Marginally Stable D Conditionally Stable Answer : B Explanation :
56.
 Transfer function of a system is  G(s)  =  K/[s2 (1 + sT)]. This open loop system is  __________ A Stable B Unstable C Marginally Stable D Conditionally Stable Answer : B Explanation :
57.
 In a closed-loop system in which the output is the speed of a motor, the output rate control can be used to A Limit the speed of the motor B Limit the torque output of motor C Limit the acceleration of the motor D Reduce the damping of the system Answer : C Explanation :
58.
 In an input signal with non-zero direct current (dc)  components is applied to a low pass  RC  network, then  DC  component in the output signal will be  ______ A The same as that in the input B Less than that in the input C More than that in the input D Zero Answer : A Explanation :
59.
 A freshly painted layer may be dried electronically by  _________ A Convective heating B Induction heating C Dielectric heating D Emissive heating Answer : C Explanation :
60.
 Two heaters rated at  1000W, 250 each are connected in series across a 250 V, 50 Hz ac mains. The total power drawn from the supply would be  __________  watt A 1000 B 500 C 250 D 2000 Answer : B Explanation :
61.
 What is the maximum length of the flexible conduit in motor installation A Less than 1.25 m/1.25 m B Less than 2.25 m/2.25 m C Less than 3.5 m/3.5 m D Can exceed not more than  5 m Answer : A Explanation :
62.
 Which among these fuse is very fast in operation A Semiconductor fuses B High rupturing capacity type C Cartridge type D Kit Kat type Answer : A Explanation :
63.
 What is the factor of safety used for current ratings in a power installation A 1 B 1.5 C 1.75 D 2 Answer : D Explanation :
64.
 Which among these is a method of wiring  Joint box Tee system Loop in system A Only I B Only II C Only I and III D I, II and III Answer : D Explanation :
65.
 Which among these is a part distribution system  Feeders Distributors Service mains A Only I B Only II C Only A and III D I, II and III Answer : D Explanation :
66.
 What is the maximum span up to which the wooden poles can be used A 20 m B 50 m C 60 m D 100 m Answer : C Explanation :
67.
 For what voltage is the H-type of poles used A 22 KV B 130 KV C 11 KV D All options are correct Answer : B Explanation :
68.
 To prevent the decaying owing to snow an rain the wooden poles are protected by _________ Aluminium Zinc Cement A Only I B Only II C Only A and III D I, II and III Answer : D Explanation :
69.
 Steel rail poles of height 13 meters are used transmission purpose of  __________  voltage. A 33 kV B 11 kV C 22 kV D BOTH 33 kV  and  11 kV Answer : A Explanation :
70.
 The squirrel-cage winding of a single-phase motor is placed in the  __________ A Armature B Stator C Rotor D Field Answer : C Explanation :
71.
 NEMA standards rate motors according to  ________ A Frame number B Horse power C Voltage D Weight Answer : A Explanation :
72.
 Which of the following motors is most suitable for signalling devices and timer A Dc series motor B DC shunt motor C Two phase induction motor D Reluctance motor Answer : D Explanation :
73.
 The purpose of skewing of rotor slots in induction motor is  _________ A To reduce the magnetic hum of the motor B To increase the distribution factor C To reduce the locking tendency of rotor D To increase the breadth factor Answer : C Explanation :
74.
 In an induction motor if the rotor resistance is equal to stand-still reactance then the maximum torque is A Less than starting torque B Equal to starting torque C More than starting torque D None of these Answer : B Explanation :
75.
 The mmf produced by a single phase winding is  _________ A Pulsating and stationary B Pulsating and rotating C Constant amplitude and stationary D Constant in amplitude and rotating Answer : A Explanation :
76.
 Usually wide and very sensitive speed control is require in case of A Reciprocating pumps B Colliery winders C Centrifugal blowers D Lathe machines Answer : B Explanation :
77.
 Inter-poles are used in  ________ A Lap wound machines B Wave wound machines C Both lap and wave wound machines D None of these Answer : C Explanation :
78.
 For the production of induced  emf  field system of an electric machine  _________ A Must be on stator B May be on stator or rotor C Must be on rotor D None of these Answer : B Explanation :
79.
 The number of conductors of the compensating winding in a DC machine A Is always more than the number of armature conductors per pole B Is always less than the number of armature conductors per pole C May be less or more than the number of armature conductors per pole D None of these Answer : B Explanation :
80.
 Two DC machines  500 kW  each are tested by Hopkinson testing method. The power input would be A 500 kW B 100 kW C 1000 kW D None of these Answer : B Explanation :
81.
 In a DC machine, how are the commutating pole winding connected A In series with the shunt winding B Parallel to the shunt winding C In series with the armature winding D Parallel to the armature winding Answer : C Explanation :
82.
 In motor circuit static frequency changers are used for  _________ A Improved cooling B Power factor improvement C Reversal of direction D Speed regulation Answer : D Explanation :
83.
 In case of traveling cranes, the motor preferred for boom hoist is  _________ A Slip ring induction motor B Squirrel cage induction motor C Synchronous motor D Single phase motor Answer : A Explanation :
84.
 Light duty cranes are generally used in  __________ A Automobile workshops B Pumping stations C Power houses D All options are correct Answer : D Explanation :
85.
 15 minutes rated motors are suitable for  ________ A Light duty cranes B Medium duty cranes C Heavy duty cranes D All options are correct Answer : A Explanation :
86.
 Free running and coasting periods are generally long in case of  __________ A Urban service B Sub-unban service C Main line service D All options are corrects Answer : C Explanation :
87.
 Arc blow is a welding defect which is encountered in   _________ A Arc welding using DC current B Arc welding using AC current C Gas welding D Thermit welding Answer : A Explanation :
88.
 Portion of the installed reserve kept in operable condition but not placed in service to supply the peak load is known as  _________ A Operating reserve B Spinning reserve C Cold reserve D Hot reserve Answer : C Explanation :
89.
 The transmission lines which feed different sub-stations represent  __________ A Primary transmission B Secondary transmission C Primary distribution D Secondary distribution Answer : C Explanation :
90.
 Transmitting power at high voltage requires more  __________ A Maintenance and protection of the equipment B Faster controls for minimising the arcing of contacts C Large controls for minimising the arcing of contacts D All options are correct Answer : D Explanation :
91.
 Copper conductors are generally used for transmission lines because it  ___________ A Has longer life and high conductivity B Is strong enough to allow long spans C Requires more support D Requires more insulators Answer : A Explanation :
92.
 The conductors used for transmitting power must have following characteristics A It should have low value of specific resistance B It should light in weight and not brittle C It should have low cost and high tensile D All options are correct Answer : D Explanation :
93.
 Steel poles are generally used for transmission lines because It has more mechanical strength and more life It occupies less space and give better appearance It has high cost Which of the above provided reason/s is are correct A Only I B Only II C Only III D Both I and II Answer : D Explanation :