SSC Junior Engineer Electrical 2018 Paper I

(A)NOR
(B)AND
(C)OR
(D)NAND

Q.2 A single phase circuit's power factor can be measured with a/an:
(A)energy meter alone
(B)combination of a voltmeter,ammeter and wattmeter
(c)Wattmeter alone
(D)combination of a voltmeter and ammeter

Q.3 'The ratio of conductor voltage across the disc nearest to the conductor multiplied by number discs' is defined as
(A)insulator efficiency
(B)disc efficiency
(C)string efficiency
(D)transmission line efficiency

(A)75 ohm
(B)150 ohm
(C)50  ohm
(D)100 ohm

Q.5 Which of the following voltage range is used in medium transmission lines?
(A)50KV to 200KV
(B)More than 200KV
(C)20KV to 100KV
(D)Less than 20KV

Q.6_________ opposes the change in the circuit voltage.
(A)Inductive reactance
(B)Resistance
(C)Capacitance
(D)Inductance

Q.7 IN a single-phase capacitor start-and-run motor,the minimum number of capacitors to be used in it is:
(A)4
(B)2
(C)1
(D)3

Q.8 A coil is wound with 50 turns and a current of a 8Amp produces a flux of 200 μWb.Calculate the inductance of the coil.
(A)0.25 mH
(B)0.125 mH
(C)2.5 mH
(D)1.25 mH

Q.9 When the supply to the excitation fails,the synchronous generator acts like a/an:
(A)Induction motor
(B)Induction generator
(C)Synchronous motor
(D)Synchronous generator 

Q.10 The cheap and temporary system of internal wiring is?
(A)Cleat wiring
(B)Conduit wiring
(C)Casing-capping
(D)CTS or TRS wiring 

Q.11 A 200V d.c machine has R_a=0.5Ω and its full-load I_a=20A.Determine the induced e.m.f when the machine acts as motor.
(A)215V
(B)210V
(C)200V
(D)190V

Q.12 Ratio of average energy demand to maximum demand during a specific period is:
(A)Power factor
(B)Utilization factor
(C)Load factor
(D)Form factor 

Q.13 What is the reason behind using a centrifugal switch in a single phase induction motor?
(A)To cut-off the starting winding at an appropriate instant
(B)To cut in the capacitor during running condition
(C)To improve the station performance of the motor
(D)To protect the motor from overloading

Q.14 Which of the following fuel has least calorific value?
(A)Kerosene oil
(B)Wood
(C)LPG
(D)Hydrogen

Q.15 Prevention of interference with neighbouring telephone lines can be done by:
(A)Reducing skin effect
(B) Reducing corona
(C)Transposing transmission lines
(D)Using bundled conductors

Q.16 An electric motor in which both the rotor and stator fields rotate with same speed is called_________.
(A)synchronous motor
(B)DC motor
(C)Universal motor
(D)Induction motor

Q.17 'H=_____'is the expression for the magnetic field due to an infinite linear current carrying conductor.
(A)µI/2πr A/m
(B)µI/2r A/m
(C)I/2r A/m
(D)I/2πr A/m

Q.18 In the speed -time curve of a train,speed in_____and time in_____ are plotted.
(A)Km/h;hour
(B)Km/s;hour
(C)Km/h;sec
(D)Km/s;sec

(A)0°
(B)60°
(C)30°
(D)90°

 Q.20 Let T be the net torque developed by the rotor runs at ⍵ rad/s.what is the mechanical poer developed?
(A)P_mech =⍵T

(B)P_mech =2π⍵/60 T

(C)P_mech =⍵/60 T

(D) P_mech =2π⍵ T

(A)R                                (C)B
(B)neutral wire                (D)Y

Q.22 In transmission line,the voltage regulation is negative whenever receiving end voltage V_R 

(A)Half of the sending end voltage
(B)Greater that the sending end voltage
(C)Equal to the sending end voltage
(D)Less that the sending and voltage

Q.23 The skin effect does not depends upon:
(A)Frequency
(B)Operating Voltage
(C)Diameter of the conductor
(D)shape of the conductor

Q.24 Direction of the arrow represents the direction of______,when the diode is forward biased.
(A)N-type material
(B)P-type material
(C)P-N Junction
(D)Conventional current flow

Q.25 4F2D is a/an___________number.
(A)Decimal
(B)Binary
(C)Octal
(D)Hexadecimal 

Q.26 ________is a tube that brings water to turbines.
(A)Forebay
(B)Spillway
(C)Penstock
(D)Trash rack

Q.27 An electric heater is connected across 230V and it draws a current of 2A.Then the resistance offered by the heater is?
(A)115 ohm
(B)11.5 ohm
(C)23 ohm
(D)230 ohm

Q.28 Find the net capacitance of the combination in which ten capacitors of 10µf are connected in parallel.
(A)50 µF
(B)0.1 µF
(C)100 µF
(D)1 µF

Q.29 Two bulbs of rating 230V,60W and 230V,100W are connected in parallel across supply mains.Identify the correct statement ?
(A)The 100W bulb will glow brighter
(B)Neither bulb will glow
(C)Both will glow equally brighter
(D)The 60W bulb will glow brighter

Q.30 Find H=_______A/m at the center of a circular coil of diameter 1m and carrying a current of 2A.
(A)2 A/m
(B)0.1636 A/m
(C)0.6366 A/m
(D)1.636 A/m

Q.31 _______is the measuring unit of inductive susceptance.
(A)Henry
(B)Mho
(C)Weber
(D)Tesla

Q.32 An alternator has 9 slots/pole.what is the value of pitch factor if each coil spans 8 slot pitches.
(A)Cos10°
(B)Cos60°
(C)Cos30°
(D)Cos45°

Q.33 If NΦ=linkage flux,then the linkage flux per unit current is defined as:
(A)Magneto motive force
(B)Leakage coefficient
(C)Inductance
(D)Inductive reactance

(A)0A
(B)0.66A
(C)1.33A
(D)1.66A

Q.35 Reflected light/Incident light =____________?
(A)Wastes light factor
(B)Reflection factor
(C)Maintenance factor
(D)Absorption factor

Q.36 _________is used to manufacture stay wire,earthwire,and structural components.
(A)Galvanised steel
(B)Nichrome
(C)Harddrawn copper
(D)Cadmium copper

Q.37 If admittance Y=a+jb,then a=?
(A)Resistance
(B)Susceptance
(C)Reactance
(D)Conductance

 









(A)D2,D3 
(B)D4,D1  
(C)D1,D2   
(D) D3,D4

Q.39 Z1 and Z2 are connected in series to form a load.A wattmeter's current coil is connected in series with the load,whereas its pressure coil is connected across Z2.The wattmeter reads:
(A)Power consumed by Z1 and Z2
(B)zero always
(C)Power consumed by Z2
(D)Power consumed by Z1 

Q.40 The trade name of the Nickel-copper alloy,that is used as a heating element is:
(A)Nichrome
(B)Eureka
(C)Steel
(D)Kanthal 

Q.41 A synchronous motor runs at 600rpm,Which of the following case is true?
(A)P=12,f=50HZ
(B)P=8,f=50HZ
(C)P=12,f=60HZ
(D)P=10,f=60HZ 

(A)A+B
(B)A
(C)A.B
(D)B

Q.43 If the field the synchronous motor is under excited the power factor will be:
(A)Unity
(B)Leading
(C)Zero
(D)Lagging

Q.44 Find the mutual inductance between two ideally coupled coils of 2H and 8H.
(A)2H
(B)4H
(C)8H
(D)16H

Q.45 In the two wattmeter method,the reading of the two wattmeter are 500W,500W respectively.The load power factor in a balanced 3-phased-3-wire circuit is:
(A)0.3
(B)0.8
(C)1
(D)0 

Q.46 Lamp efficiency is measured in_______
(A)Lux/watt
(B)Candel/watt
(C)Lumen/watt
(D)Lumen/lux 

Q.47 The below symbol which is used in single line diagram represents______

(A)Current breaker
(B)Current transformer
(C)Power transformer
(D)Potential transformer

Q.48 _________Power plant is the plant which uses non-conventional source of energy.
(A)Wind
(B)Hydroelectric
(C)Nuclear
(D)Thermal

Q.49 If an alternator is operating at unity power factor,then its terminal voltage is:
(A)equal to the induced EMf,with zero voltage regulation
(B)Less than the induced EMF,with negative voltage regulation
(C)Less than the induced EMF,with positive voltage regulation
(D)Greater than the induced EMF,with negative voltage regulation 

(A)2.4 V
(B)1.2V
(C)24V
(D)12V


Q.51 If the copper loss of a transformer at half full load is 400W,then the copper loss corresponding to full load is:
(A)1200W
(B)400W
(C)1600W
(D)800W

Q.52 At f=______;R-L-C series circuit operates at unity power factor.
(A)1/RC
(B)1/2𝝿√LC
(C)1/LC
(D)1/RLC 

Q.53 In electric traction,the coefficient of adhesion is represented by:
(A)ჶ
(B)Ɣ
(C)𝛌
(D) µ

Q.54 Two coupled coils with L1=L2=0.5H have a coupling coefficient of K=0.75.The turn ratio N1/N2=?
(A)4
(B)2
(C)0.5
(D)1


Q.55 Which of the following losses is together called iron losses?
(A)Eddy current loss and hysteresis loss
(B)Hysteresis loss and copper loss
(C)Eddy current loss frictional loss
(D)Hysteresis loss and frictional loss


Q.56 ______motor is referred to as a universal motor?
(A)Shunt
(B)Single phase induction
(C)Series
(D)Synchronous

Q.57 Hysteresis loss is NOT a function of_________
(A)Ambient temperature
(B)Volume of a material
(C)Steinmetz co-efficient of a material
(D)Frequency

Q.58 Identify the INCORRECT statement with regards to synchronous motors.
(A)The field winding is placed on the rotor
(B)The armature winding is placed on the stator
(C)It is a constant speed motor
(D)It is a self-starting machine

Q.59 What would the total loss of the 2KVA transformer corresponding to maximum efficiency be,provided the transformer has iron loss of 150W and full-load loss of 250W?
(A)300W
(B)500W
(C)400W
(D)100W

(A)10ohm
(B)2ohm
(C)5ohm
(D)1ohm

Q.61 The function of condenser in thermal power plant is:
 
(A)Condense water
(B)Condense used steam into water
(C)Purify steam
(D)Purify water 

Q.62 ________starting method CANNOT be used for starting a 3-phase squirrel cage induction motor.
 
(A)Direct-on-line
(B)Auto-transformer
(C)Rotor-resistance
(D)star-delta

Q.63 The laws involved in the expression e=-dჶ/dt,are__________
(A)Coulomb,s and faraday,s laws
(B)Coulomb,S and ampere,s laws
(C)Faraday,s and Lenz,s laws
(D)Faraday,s and ampere,s laws

Q.64 If an AC circuit is supplied with an active power of 500W reactive power 500VAR,then the load power factorof the circuit is:
(A)0
(B)0.5
(C)1
(D)1/√2

Q.65 which of the following should be used under no-load conditions?
 
(A)Rewireable fuse
(B)Isolator
(C)Air-breaker switch
(D)Circuit breaker 

(A)V₂

(B)-(V₂-V₁)

(C)V₂-V₁

(D) V₁

 

 














(A)DC shunt motor
(B)DC short shunt compound motor
(C)DC short shunt compound generator
(D)DC long shunt compound generator

Q.68 which of the following plants experiences chain relations?
 
(A)Nuclear power plant
(B)Gas power plant
(C)Hydro-electric power plant
(D)Thermal power plant

Q.69 Identify the important feature of a DC series motor.
 
(A)Low starting torque
(B)zero starting torque
(C)Medium starting torque
(D)High starting torque

Q.70 Three lamps are connected in series across a 120V supply and take a current of 1.5A.If the resistance of two of the lamps is 30ohm,what is the resistance of he third lamp?
 
(A)20ohm
(B)40ohm
(C)30ohm
(D)10ohm

Q.71 The law that explains about  the economic size of a conductors is:

(A)Kelvin's law
(B)Faraday's law
(C)Lambert's law
(D)Newton's law

Q.72 For a three layer stranded wire, the number of strands in first, second and third layer respectively are:
(A)1,7 and 14
(B)1,5 and 10
(C)1,6 and 12
(D)1,4 and 8

Q.73

(A) 4Ω
(B) 5Ω
(C) 7Ω
(D) 6Ω

Q.74 Two identical coils A and B of 1000 turns each lie in parallel plane such that 80% of the flux produced by one coils links with the other. If a current of 5A flowing in A produces a flux of 0.05mwb, then the flux linking with coil B is:

(A)0.004mwb
(B)0.4mwb
(C)4mwb
(D) 0.04mwb

Q.75 Which of the following is the correct relation regarding coupled coils?

(A)M=(L1-L2)/2
(B)M≤ (L1L2)^0.5
(C) M=(L1+L2)/2
(D)M＞(L1L2)^0.5 

Q.76 split-phase, capacitor and shaded-pole single-phase motors classified as:
(A)Repulsion motors
(B)1-phase induction motors
(C)A.C. series motors
(D)Un-excited synchronous motors  

Q.77 Power factor of an A.C. circuit is equal to
(A)Z/R
(B)R/XC
(C)R/ XL
(D)R/Z 

Q.78 The meter constant of an energy meter will be given in:
( A)KW/Revolutions
(B)KWh/Revolutions
(C)Revolutions/KW
(D)Revolutions/KWh 

Q.79 Relate 'Reluctance' with the following:
(A)weber/m
(B)A/Weber
(C)Weber/A
(D)A/m 

Q.80 Two inductors of 4H and 6H are connected in series . The equivalent inductance of this combination is:
(A)10H
(B)6H
(C)4H
(D)2.4H 

Q.81 If dΦ is the luminous flux incident normally on an area dA, then illuminance is given as:
(A)dΦ/dA
(B)Φ x A
(C)dA/dΦ
(D)dΦ-dA

Q.82 A magnetic circuit is applied with a current that changes at a rate of 5A/sec. The circuit has an inductance of 2H, then the self-induced EMF is:
(A)-10V
(B)-2.5V
(C)0.4V
(D)-4V 

Q.83 Hunting occurs in a/an________ motor.
(A)Induction
(B)Synchronous
(C)DC shunt
(D)DC series 

Q.84 Extension of moving iron ammeter range can be done by using
(A)Multiplier
(B)Shunt
(C)capacitor
(D)Inductor 
 
 

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A.C. Bridges- Electrical and Electronic Measurement

A.C. Bridges

INTRODUCTION.:- Alternating current bridge methods are of outstanding importance for measurement of electrical quantities. Measurement of inductance,capacitance, storage factor, loss factor may be made conveniently and accurate by employing a.c. bridge networks.

       The a.c. bridge is a natural outgrowth of the wheastone bridge. An a.c. bridge, in its basic form,consists of four arms, a source of excitation ,and a balance detector. In a.c. bridge each of the four arms is an impedance, and the battery and the galvanometer of the wheatstone bridge are replace respectively by an a.c. source and a detector sensitive to small alternating potential differences.

       The usefulness of a.c. bridge circuits is not restricted to the measurement of unknown impedances and associated parameters like inductance,capacitance, storage factor, dissipation factor, etc. These circuits find other application in communication system and complex electronic circuits. Alternating current bridge circuit are commonly used for phase shifting, providing feedback paths for oscillators and amplifiers, filtering out undersirable signals and measuring the frequency of audio signals.

Fig: Basic a.c. bridge network

SOURCES AND DETECTORS. :- For measurements at low frequencies, the power line may act as the source of supply to the bridge circuits. For higher frequencies electronic oscillators are universally used as bridge source supplies. These oscillators have the advantage that the frequency is constant, easily adjustable, and determineable with accuracy. The waveform is very close to a sine wave, and thier power output is sufficient for most bridge measurements. A typical oscillator has a frequency range of 40 Hz to 125 KHz with a power output of 7 W.

The detectors commonly used for a.c. bridge are 
(i) Head phones
(ii) Vibration galvanometers, and
(iii) Tuenable amplifier detectors.

Head phones are widely used as detectors at frequencies of 250 Hz and over upto 3 or 4 kHz. They are most sensitive detectors for this frequency range. 

 when working at a single frequency a tuned detector normally gives the greatest sensitivity and discrimination against harmonics in the supply.  

Vibration galvanometers are extremly useful for power and low audio frequency range. Vibration galvanometers are manufactured to work at various frequencies ranging from 5 Hz to 1000 Hz but are most commonly used below 200 Hz as below this frequency they are more sensitive than the head phone.

Tuenable amplifier detectors are the most versatile of the detectors.The transistor amplifier can be tuned electrically and thus can be made to respone to a narrow bandwidth at the bridge frequency. The output of the amplifier is fed to a pointer type of instrument. This detector can be used, over a frequency range of 10 Hz to 100 kHz.

 

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Intelligence Bureau (IB) Security Assistance/Executive Examination 2018-2019 (Tier-1) Question Paper with answer.

1)Volume of a cone with radius r height h is :

(A)rh^2 (B)πr^2h/2 (C)πrh/3 (D)πr^2h/3

2)International Day of yoga is celebrated annually on :

(A)21 June (B)10 December (C)21 June (D)21 September  

3)City of lakes in india is :

(A)Lucknow (B)Chandigarh (C)Bengaluru (D)Udaipur

4)Which of the diseases is not caused by virus ?
(A)TB (B)Chickenpox (C)Dengue (D)Polio

5)How many states are there in india ?
(A)26 (B)28 (C)27 (D)29  

6)During Akbar's regime,who carried out land revenue reforms :
(A)Mann Singh (B)TodarMal (C)Birble (D)Tansen

7)Which of the following is the unit of heat ? 
(A)Joule (B)Ohm (C)Ampere (D)Volt 

8)Who among the following is the future Buddha that is yet to come ?
(A) Lokes Varna (B)Maitreya (c)Laughing Buddha (D)Chanakya

9)Jaundice is caused due to malfunctioning of :
(A)Liver (B)stomach (C)Pancreas (D)Kidney

10)Tsangpo river flowing through Tibet is known in india as :
(A)Brahmputra (B)Ganges (C)Sutlej (D)Beas

(11)Yuri Gagarin,the first cosmonaut to reach space,was from which country ?
(A)UK (B)Japan (C) China (D)Russia

(12)What is boiling point of water in Fahrenheit ?
(A)100℉ (B)32℉ (C)212℉ (D)0℉

13)Kalibangan,the indus valley site,is in :
(A)Rajasthan (B)Gujarat (C)Madhya Pradesh (D)Uttar Pradesh

14)Who was the founder of Banaras Hindu University ?
(A)Sukumar Dey (B)Madan Mohan Malviya (C)Dr.Rajendra Prasad (D)Motilal Nehru

Electric Fuse - Advantage and Disadvantage

Fuses

A Fuse is a small piece of metal inserted in a fuse circuit, which melts on excessive flow through this and thus breaks the circuit.

Fuse element is usally made of low melting point,high conductive material and least fall due to oxidation e.g.,sliiver,copper etc.  

Advantages
(i)It is the cheapest from of protection available.
(ii)It requires no maintenance.
(iii)Its operation is inherently completely automatic unlike a circuit breaker which requires an elaborate equipment for automatic action.
(iv)It can break heavy short-circuit current without noise or smoke.
(v)The smaller size of fuse element impose a current limiting effect under short-circuit conditions.
(iv)The inverse time-current characteristic of a fuse makes its suitable for overcurrent protection.
(vii)The minimum time of operation can be made much shorter than with the circuit breakers.
 
Disadvantages
(i)Considerable time is lost in rewiring or replacing a fuse after operation.
(ii)On heavy short-circuit,discrimination between fuses in series cannot be obtainted unless there is sufficient difference in the sizes of the fuses concerned.
(iii)The current-time characteristic of a fuse cannot always be co-related with that of the protected apparatus.