## practice set

### SSC JE ELECTRICAL PRACTICE SET - 8

1.
 Which effect of the electric currents is utilized in a filament lamp A The heating effect B The magnetic effect C The collision ionization of the gases D The chemical effect Answer : A Explanation :
2.
 Which of the following statements about electric voltage is true A Voltage is the directed movement of electrons B Voltage causes current to flow C Voltage is the irregular movement of electrons D Voltage is not always needed to cause the flow of current Answer : B Explanation :
3.
 A material which is slightly repelled by a magnetic field is known as  ___________ A Diamagnetic material B Paramagnetic material C Ferro-magnetic material D None of these Answer : A Explanation :
4.
 Internal resistance per cell of Lead Acid cell is always  __________ A Less than Edision cell B More than Edision cell C Equal to Edision cell D None of these Answer : A Explanation :
5.
 Mica capacitors are characterised by all of the following except  ___________ A Accurate value B Low losses C Low leakage resistance D Stable operation Answer : C Explanation :
6.
 In a capacitor, the electric charge is stored in  ___________ A Dielectric B Metal plates C Dielectric as well as metal plates D Neither dielectric nor metal plates Answer : A Explanation :
7.
 When a dielectric placed in an electric field, the field strength  __________ A Increases B Decreases C Remain unchanged D Reduces to zero Answer : B Explanation :
8.
 The maximum value potential gradient in a cable occurs in  ___________ A Conductor B Insulation C Outer sheath D None of these Answer : A Explanation :
9.
 A six dot mica capacitor colour coded, white, red, green, brown, red and yellow has the capacitance value of  ____________ A 25 pF B 124 pF C 250 pF D 925 pF Answer : D Explanation :
10.
 A charge exists on a conductor. The best way to remove this charge is to  _________ A Isolate the conductor from other charges B Ground the conductor C Create vacuum around the conductor D None of these Answer : B Explanation :
11.
 A current of  5A  flows through a conductor against a potential difference of  200V. the power dissipated will be  _________ A 1000 W B 1.1 kW C 2000 W D 100 W Answer : D Explanation :
12.
 Energy (in units) consumed by a heater of rating  1000 W  by operating it for a period of  2 hours  will be  __________ A 1.5 B 2 C 2.5 D 4 Answer : B Explanation :
13.
 Copper has less resistance than aluminium and has greater tensile strength than aluminium. To work, copper proves an excellent material as compared to aluminium. In spite of this, nowadays aluminium is extensively used in transmission and distribution of power supply because A It is cheaper than copper B Copper is not available C It is light in weight D It is easily available Answer : A Explanation :
14.
 The resistance  R1  and R2  are connected in parallel. The ratio of values of resistance  R1 : R2  ia  4 : 1.  The current in  R1 : R2  will be equal to  ________ A 4 : 1 B 1 : 4 C 1 : 1 D 4 : 4 Answer : B Explanation :
15.
 Kirchhoff’s law states that in a closed loop of a circuit  ________ A The total current, algebraically summed is zero B The algebraic sum of the potential differences zero C Ponents is zero D None of these Answer : B Explanation :
16.
 Does the electric current always produce a magnetic field A No, only large currents produce a magnetic field B No, a magnetic field is produced only in the presence of an iron core C No, a magnetic field is produced only in the presence of a coil D Yes, the electric current always produce a magnetic field Answer : D Explanation :
17.
 Comparing a magnetic circuit with an electric circuit the equivalent for the magnetic flux is ___________ A The conductivity of the line B The resistance of the load C The current in the lines D The voltage of the source Answer : C Explanation :
18.
 In an  RC-coupled common Emitter amplifier A Coupling capacitance affects the  hr  response and bypass capacitance affects the  If response only B Both Coupling and bypass capacitance affects the  If response only C Both Coupling and bypass capacitance affects the  hr response only D Coupling capacitance affects the  If  response and the bypass capacitance affects the  hr response Answer : B Explanation :
19.
 The threshold voltage of an  n-channel  MOSFET  can be increased by  ___________ A Increasing the channel doping concentration B Reducing the channel doping concentration C Reducing the gate oxide thickness D Reducing the channel length Answer : B Explanation :
20.
 The transit time of the current carriers through the channel of an  FET  decides its  __________  characteristics A Switching B On / off C Dynamic D Load Answer : A Explanation :
21.
 The drift velocity of elements, in silicon  ____________ A Is proportional to the electric  field for all values of electric field B Is independent of the electric field C Increases at low values of electric field and decreases at high values of electric field exhibiting negative differential resistance D Increases linearly with electric field at low values of  electric field and gradually saturates at higher values of  electric field Answer : A Explanation :
22.
 Thermal runaway in a transistor biased in the active range is due to  __________ A Heating the transistor B Changes   in   which Increase with temperature C Base emitter voltage  VBE  which decreases with rise in temperature D Change in reverse collector Saturday current due to rise in temperature Answer : D Explanation :
23.
 An external resistance added in the field of a  dc  shunt generator will  __________ A Increase the speed of the generator B Increase the voltage of the generator C Decrease the voltage of the generator D Increase the power delivered Answer : C Explanation :
24.
 Torque of a motor is  ___________ A Force (in N-m) acting on the motor B The product of tangential force on the rotor and its radius C The electrical power in  kW D The power given to load being driven by the motor Answer : B Explanation :
25.
 The terminal board of a motor is as shown in the diagram. Which type of motor is this A A compound motor with commutating pole Winding B A shunt motor with commutating pole Winding C A shunt motor without commutating pole Winding D A series motor with commutating pole Winding Answer : D Explanation :
26.
 The speed of a series motor at no load is  ____________ A Zero B 3000 rpm C 3600 rpm D Infinity Answer : D Explanation :
27.
 The field flux of a dc motor cab be controlled to achieve  _____________ A The speed is lower than rated speed B The speed is higher than rated speed C The speed is at rated speed D None of these Answer : B Explanation :
28.
 What will happen if the supply terminals of dc shunt motor are interchanged A Motor will stop B Motor will run at its normal in the same direction as it was running C The direction of rotation will reverse D Motor will run at a speed lower than the normal speed in the same direction Answer : B Explanation :
29.
 Resistivity of a semiconductor depends on  ____________ A The length of the semiconductor specimen B Cross-sectional area of the semiconductor specimen C Volume of the semiconductor specimen D The atomic nature of the semiconductor Answer : A Explanation :
30.
 A germanium atom contains   __________ A Four valence electrons B Six valence electrons C Four protons D Six protons Answer : A Explanation :
31.
 A hole is the vacancy created when  ___________ A A free electron moves on application of electric field B An electron braks its covalent band C An atomic core moves D An electron reverts from conduction band to valence band Answer : B Explanation :
32.
 Forbidden energy gap between valence band and conduction band is least in the case of  ___________ A Mica B Pure silicon C Pure germanium D Impure silicon Answer : D Explanation :
33.
 Donor impurity atom in a semiconductor  result in new  _____________ A Wide energy band B Narrow energy band C Discrete energy level just below conduction level D Discrete energy level just above valence  level Answer : C Explanation :
34.
 A p-type semiconductor   is  ____________ A Positively charged B Negatively charged C Electrically neutral D Not used in semiconductor   devices Answer : C Explanation :
35.
 Change of carrier concentration along the length of semiconductor   is called  ___________ A Mobility B Diffusion C Concentration gradient D Drift Answer : C Explanation :
36.
 In a semiconductor, movement of charge carriers under influence of an electric field is called  ____________ A Diffusion B Drift C Mobility D Conductivity Answer : B Explanation :
37.
 In pure silicon, major part of the drift current in due to free electrons because  ___________ A There are more free electrons than holes B Free electrons are in the valance band C Mobility of electrons is greater than the mobility of holes D Diffusion constant of electrons  in greater than that of holes Answer : C Explanation :
38.
 Semiconductor may be made  n-type by adding donor impurity  __________ A During zero refining B During chemical purification C During crystal pulling D Before purification process Answer : C Explanation :
39.
 When the plate area of a parallel plate capacitor is increased keeping the capacitor voltage constant, the force between places A Increases B Decreases C Remains constant D May increase or decrease on the metal making up the plates Answer : A Explanation :
40.
 Energy stored in a capacitor over a cycle when excited by an ac source is  _________ A Same as that to  a dc source at equivalent magnitude B Half of at due to a dc source at equivalent magnitude C Zero D None of these Answer : C Explanation :
41.
 Inside a hollow conducting spere, electric field  ___________ A Is zero B Is a non-sero constant C Change with the magnitude of the charge given to the conductor D Changes with distance from the centre of the sphere Answer : A Explanation :
42.
 The resistance of a strip of copper of rectangular cross-section is 2 Ω A metal of resistivity twice that of copper is coated on its upper surface to a thickness equal to that of copper strip. The resistance of composite strip will be  __________ A 6 Ω B 4/3 Ω C 3/2 Ω D 3/4 Ω Answer : B Explanation :
43.
 Two coupled coils of  L = 0.8H and  L = 0.2H have a coupling coefficient k = 0.9.  The mutual inductance  M is  ___________ A 0.144 H B 0.23 H C 0.36 H D 0.43 H Answer : C Explanation :
44.
 A coil with large distributed capacitance has a  ___________ A High Q B Low Q C Low resonant frequency D High resonant frequency Answer : D Explanation :
45.
 A megaohm-meter reading of zero or low ohms is indicated between the stator winding and motor frame. The winding is  __________ A Open B Series connected C Grounded D Cross connected Answer : C Explanation :
46.
 A capacitor motor has difficulty of starting. What is the probable cause A Reversed magnetic field B Shorted commutator segments C Shorted winding D All options are correct Answer : C Explanation :
47.
 To a highly inductive circuit, a small capacitance is added in series. The angle between voltage and current will  __________ A Increase B Decrease C Remain nearly the same D Become indeterminant Answer : B Explanation :
48.
 After the starting winding is disconnected from the circuit, the motor continues to run only on the  _______ A Squirrel-cage winding B Running winding C Magnetic winding D Compensating winding Answer : B Explanation :
49.
 If the rotor of a 3-phase induction motor is assumed purely resistive, then electromagnetic torque is  _________ A Minimum with load angle of 90 degree B Minimum with load angle of 0 degree C Optimum with load angle of 90 degree D Optimum  with load angle of 0 degree Answer : D Explanation :
50.
 The commutator in a repulsion motor provides  _____ A Armature winding B Stator winding C Short-circuiting device D Starting winding Answer : A Explanation :
51.
 Which of the following motor has a squirrel-cage winding embedded in the armature under the regular winding A Compound motor B Repulsion-start, induction-run motor C Repulsion motor D Repulsion- induction motor Answer : D Explanation :
52.
 A moving-iron meter will operate on  ___________ A AC circuit only B DC circuit only C Either AC or DC circuit D AC or DC when a rectifier is used Answer : C Explanation :
53.
 Electro dynamometers are used extensively for the measurement of  ___________ A Magnetic lines of force B Resistivity C Capacitor networks D Power Answer : D Explanation :
54.
 If a wattmeter is used in a circuit it is safe voltage or current rating is exceeded, the meter will  ___________ A Not be affected B Operated erralically C Immediately peg the pointer D Not indicate the overload Answer : D Explanation :
55.
 A varmeter is used to indicate the  ___________ A Internal AC overloads B Out-of-phase voltage change C Amount of reactive change D Amount of true power Answer : C Explanation :
56.
 Which of the following does a power factor meter indicate A Continuous power B Power difference between phases C The current is leading or lagging the voltage D Reactive and useful power Answer : C Explanation :
57.
 What three electrical quantities can be measured by a multi-meter A What three electrical quantities can be measured by a multi-meter B Voltage, current and resistance C Voltage, current and amperes D Voltage, watts and VARs Answer : B Explanation :
58.
 A multi-meter uses different multipliers to increase the  __________ A Current range B Voltage range C Resistance range D Impedance range Answer : B Explanation :
59.
 When a wheat-stone bridge is balanced, the galvanometer reads A Zero current B Maximum current C Zero voltage D Maximum voltage Answer : A Explanation :
60.
 What type of a bridge circuit is used to measure inductance and capacitance A Wheat-stone bridge B DC bridge C AC bridge D AC, DC bridge Answer : C Explanation :
61.
 A build-type voltage tester is recommended only for circuits at or number how many volts A 120 volts B 240 volts C 480 volts D 600 volts Answer : A Explanation :
62.
 The amortisseur winding in a synchronous motor _____ A Provides starting torque only B Provides starting toque and eliminates hunting C  Improves the power factor of the machine D None of these Answer : B Explanation :
63.
 When a synchronous motor is started, the field winding is initially  ____________ A Short circuited B Open circuited C Excited by a dc source D None of these Answer : A Explanation :
64.
 If the excitation and terminal voltage of synchronous motor are kept constant and the load is increased then  _____________ A Armature current decreases and power factor becomes power leading B Armature current increases and power factor becomes more leading C Armature current increases and power factor becomes more lagging D None of these Answer : C Explanation :
65.
 In a synchronous motor  __________ A The rotor mmf and stator mmf are stationary with respect to each other B The speed of rotor mmf is slightly less than the speed of stator mmf C The speed of rotor mmf is slightly more than the speed of stator mmf D None of these Answer : A Explanation :
66.
 Under short circuit conditions, the power factor of an alternator is  ___________ A Almost zero lagging B Unity C About 0.6 lagging D None of these Answer : A Explanation :
67.
 The rated voltage of alternators used in power stations is usually  __________ A 11 kV B 66 kV C 132 kV D 400 kV Answer : A Explanation :
68.
 A transformer has a core loss of 64 W and copper loss of 144 W, when it is carrying  20%  overload current. The load at which this transformer will operate at the maximum efficiency  ___________ A 80% B 66% C 120% D 44% Answer : A Explanation :
69.
 Two transformers operating in parallel will share the load depeanding upon their  ___________ A Efficiency also B Ratings also C Leakage resistance D None of these Answer : B Explanation :
70.
 Which of the following transformers is smallest A 1 kVA, 50 Hz B 1 kVA, 200 Hz C 1 kVA, 400 Hz D 1 kVA, 600 Hz Answer : D Explanation :
71.
 The short-circuit test in a transformer is used to determine  ___________ A Iron loss at any load B Copper loss at any load C Hysteresis loss D Eddy-current loss Answer : B Explanation :
72.
 Under heavy loads, transformer efficiency is comparatively low because  ___________ A Voltage drops both in primary and secondary becomes large B Secondary output is much less as compared to primary input C Copper loss becomes high in proportion to the output D Iron loss is increased considerably Answer : C Explanation :
73.
 In relation to a transformer the ratio  20 : 1 indicates that  _________ A There are  20 turns on primary and one turn on secondary B Secondary voltage is  1/20Th of primary voltage C Primary current is 20 times greater than secondary current D For every  20 turns on primary, there is one turn on secondary Answer : D Explanation :
74.
 Overhead lines generally use  ___________ A Copper conductors B All aluminium conductors C ACSR conductors D None of these Answer : C Explanation :
75.
 High voltage transmission lines use  ____________ A Pin insulators B Suspension insulators C Shackle, insulators D None of these Answer : B Explanation :
76.
 The criterion for selection of size of conductor for a feeder is  ________ A Voltage drop B Corona loss C Temperature rise D Radio interference Answer : C Explanation :
77.
 The weight of a locomotive is  120  tonnes. If the axle load is not to exceed 20 tonnes, the number of axles required is  _________ A 12 B 3 C 7 D None of these Answer : D Explanation :
78.
 A lighting sub-circuit has 100 W lamps. If the rated current of the fused in this circuit is 5A, the maximum number of light points on this circuit without violating regulations and safety should be  _______ A 8 B 9 C 14 D 16 Answer : B Explanation :
79.
 What is the minimum permissible size of the earth continuity conductor A 6 sq. mm B 9 sq. mm C 11 sq. mm D 13 sq. mm Answer : A Explanation :
80.
 The function of the depolarizer in a carbon zinc cell is that  __________ A It converts the produced hydrogen into water B It prevents the fast chemical action on the zinc container C It synthesis the decomposed electrolyte D It absorbs the oxygen produced in the cell Answer : A Explanation :
81.
 Midway between two equal and similar charges, a third equal and similar charge is placed. Then this third charge will  ___________ A Remain in stable equilibrium B Be in unstable equilibrium C Not be in equilibrium D Will move out of the field to influence the two charges Answer : A Explanation :
82.
 Two parallel conductors are carrying currents in the same direction. Which of the following statements is correct A There is a repelling force B The force increases when  the current is decreased C There is an attracting force between  the conductors D The force increases when the distance between the conductors is increased Answer : C Explanation :
83.
 Is it possible to prevent by very fast operation of the switch the switching spark produce during switching off of an inductance A No, the faster the circuit is opened, the higher is the self-induced voltage B Yes, as long as the circuit is opened fast enough C Yes, as long as the switch can withstand the high switching speed D Yes, if the current is less than 50 A Answer : A Explanation :
84.
 A contactor coil is designed for 220V, DC. What happens if it is connected to 220V AC A A too large current is drawn by the coil and it is destroyed B A too small current is drawn by the coil and the operation of the contactor is no longer certain C The permanent magnet of the magnetic system is demagnetized D The coil insulation is quickly damaged by the alternating voltage Answer : B Explanation :
85.
 Which of the following is true about coefficient of adhesion A It is same on AC and DC traction systems B It is high in case of DC traction and low in AC traction C It is low in case of AC traction  and high in DC traction D None of these Answer : D Explanation :
86.
 Which of the following indicates the usual specific energy consumption for suburban train service A 18 to 25 watt-hours per tonne km B 50 to 75 watt-hours per tonne km C 125 to 150 watt-hours per tonne km D 155 to 200 watt-hours per tonne km Answer : B Explanation :
87.
 Which of the following is the reason for the sound produced by horn in automobiles A Magnetostriction B Vibrating diaphragm C Moving coil D Oscillating coil Answer : B Explanation :
88.
 How is the miniature lamps on automobiles used A It is used as tail lamp B It is used as dash board lamp C It is used as side lamp D All options are correct Answer : D Explanation :
89.
 For low and medium power  derives, where speed control is not required, the motor that is recommended is  _____________ A Synchronous motor B Squirrel cage induction motor C Double cage induction motor D Three-phase series motor Answer : B Explanation :
90.
 Why is the energy consumption in propelling the train required for ? Acceleration Work against gravity while moving up the gradient Work against the resistance to motion A I and II B Only I C I, II and III D I and III Answer : C Explanation :
91.
 Which of the following is true about low frequency operation of AC series motor A It improves its commutation property but affects adversely the p.f. and efficiency B It improvers its commutation property p.f. and efficiency C It affects adversely commutation but improves p.f. and efficiency D None of these Answer : B Explanation :
92.
 Two locomotives having identical tractive-effort-slip characteristic haul a heavy train. The locomotive with larger diameter shares  __________ A Larger tractive effort B Smaller tractive effort C Equal tractive effort D Equal tractive effort Answer : B Explanation :
93.
 Which of the following is the range of the efficiency of a welding motor generator A 90 to 95 % B 80 to 90% C 50 to 60% D 30 to 45% Answer : B Explanation :
94.
 The  12 mm  steel plates are to be welded using arc welding. Electrode of No. 8 is to be used. What will be the current requirement A 10 A B 50 A C 100 A D 150 A Answer : D Explanation :