| Post Name | ASST. PROFESSOR IN ELECTRICAL AND ELECTRONICS ENGG. - TECH. EDN |
|---|---|
| Question Paper Code | 080/2023 |
| Category Code | 724/2021 |
| Date of Test | 20 June 2023 |
| Medium of Question | ENGLISH |
| Exam Type | OMR Examination |
| Total Questions | 100 |
1
Assertion (A) : Kirchhoff’s Voltage Law states that the algebraic sum of all voltages around
a closed path in a network is Zero.
Reason (R) : Law of conservation of charge is the basis of Kirchhoff’s Voltage law.
Answer
C. are true and
2
Twelve 6 H inductors are used as edges to form a cube, determine the equivalent inductance
seen between the two diagonally opposite corners of the cube :
Answer
B. 5H
3
Find the current through the 3 resistor using Superposition theorem :
Answer
A. 5.625 A
4
Find the maximum power that can be transferred to RL :
Answer
C. 1.099 W
5
In an ac series RLC circuit, the voltage across R and L is 20 V, voltage across L and C is 9 V
and voltage across RLC is 15 V. What is the voltage across C?
Answer
A. 7 V
6
In a parallel resonance circuit, why does the current lag behind the source voltage at
frequencies below resonance?
Answer
B. Because circuit is predominantly inductive
7
If the impedance parameters are given as p A then the corresponding circuit or two port
network will be:
MM. 2 e ;
R - -
1 2 ] R
Answer
B. R/2
—WA__ WA ° MM °
8
Obtain the equivalent capacitance of the network given :
Answer
B. 1.9 F
9
In order to produce a flux of 100 Wb in an airgap of length 0.2 mm and area of cross-
section is 1 cm2, the MMF required is :
Answer
A. 500 /
10
A ring-shaped coil with fixed number of turns of it carries a current of certain magnitude. If
an iron core is threaded into the coil without any change in coil dimensions, the magnetic
induction density will :
Answer
D. Increase
11
What is the main difference between first order LPF and second order LPF?
Answer
Question Cancelled
12
If the voltage and current in an AC circuit are given by v 200 sin ( t 30 ) and
i 10 sin ( t 60) then power factor of the circuit is :
Answer
B. 0
13
The electric field inside a perfectly conducting media is :
Answer
B. Zero
14
Two point charges Q1 1 nC and Q2 2 nC are at a distance apart. Which of the following
is incorrect?
Answer
D. As the distance between them decreases, the force on Q1 increases linearly
15
Two identical co-axial circular coils carry same current I but in opposite direction. The
magnitude of magnetic field B at a point on the axis midway between the coils is :
Answer
A. Zero
16
Unit of Poynting vector is :
Answer
D. Watt/m2
17
The Stoke’s theorem can be used to find which of the following?
Answer
Question Cancelled
18
Find the magnetic field when a circular conductor of very high radius is subjected to a
current of 12 A and the point P is at the centre of the conductor :
Answer
B. 0
19
The Laplace transform of i(t ) tends to I ( s ) . As t , the value of i(t ) tends to :
s(1 s)
Answer
D. 2
20
A system is defined by its impulse response h(n ) 2n u(n 2) . The system is :
Answer
C. Causal but not stable
21
The signal x [n] e jn e j 2n is :
Answer
C. Not an Eigen function of LTI system
22
If u(t ) denotes the unit step function, which of the following is an example of a bounded
signal :
Answer
C. e 2t u(t )
23
Find the z-transform of (n 1)2 :
z 2 ( z 1) (2z 1)
Answer
A. (2z +
24
The system y(t ) x 2 (t ) is :
Answer
B. Non linear and non invertible
25
A 125 V, 50 Hz, single phase transformer has rated eddy current loss of 125 W. If the
transformer is operated from 200 V, 40 Hz supply mains, then new eddy current loss is :
Answer
D. 320 W
26
A 500 kVA transformer with 0.05 p.u. reactance is connected in parallel with a 250 kVA
transformer with 0.04 p.u. reactance. The secondary voltage of each transformer is 400 V on
no-load. Find the common load they can share without over loading any transformer at unity
power factor :
Answer
C. 650 kVA
27
A rectangular coil loop with effective conductor side length l , axial radius of the loop r ,
rotating at an angular velocity w, in a steady magnetic flux density B, then the e.m.f. induced
in the loop is given by :
Answer
D. 2B l w r
28
Identify correct and incorrect statements related to armature reaction and commutation
process in DC machine :
I. In a DC motor, due to armature reaction, the shift in magnetic neutral axis is in same
direction of rotation.
II. The polarity of the interpoles must be of the same polarity as the next upcoming main
pole in a DC generator.
di
III. Compensating winding cancel the armature reaction effect, but not L effect.
dt
Answer
D. I is incorrect, but II and III are correct
29
Torque and speed relationship in a DC series motor is given by :
1
Answer
A.
30
A 100 hp, 250 V, 350 A dc shunt motor with an armature resistance of 0.05 , is started by a
starter having 4 stages of resistances. Starter is designed to limit maximum starting current
to twice its rated value and its starting minimum current to rated value. The total resistance
of starter is :
Answer
Question Cancelled
31
Identify correct and incorrect statements related to synchronous machine :
I. The synchronizing torque or stiffness of coupling, in a synchronous machine, increases
with increase in load angle ‘ ’
II. The Steady state stability limit or maximum power transfer condition, in cylindrical
rotor and salient pole synchronous machine, occurs at load angle 90
Answer
A. I and II both are incorrect
32
Identify the incorrect statement related to synchronous machine :
Answer
D. A largely Under Excited Synchronous Motor delivers P and consumes Q, with
lagging power factor
33
The commutator pitch for 4 pole, 50 commutator segment, retrogressive, Duplex-wave wound
DC machine is :
Answer
C. 24
34
If a squirrel cage induction motor, when started with 50% tapping in case of
auto-transformer starter and stator reactor starter, then the ratio of starting currents
respectively is :
Answer
C. 1
35
If the ratio of, slip at maximum torque to slip at full-load torque is 4, then the ratio of
maximum torque to full-load torque is (neglect stator resistance) :
8
Answer
B. 17 8
4
36
In a 4 pole dc machine brushes are moved 4 electrical from M.N.A. The mechanical angle
through which brushes have been shifted is :
Answer
A. 2
37
The node admittance matrix for a three bus system is given by J 5 J 25 J 20 . If line
J10 J 20 J 30
connected between nodes (2) and (3) with line admittance of J 20 ℧ is removed, then the
new node admittance matrix is given by
J15 J5 J10 J15 J 5 J10
Answer
D. J5 J5 0
J10 0 J 50 J10 0 J10
38
If a power system consists of one slack bus, m generator buses, and n load buses, then the
J J 2
size of the J 2 sub-matrix in the Jacobian matrix 1 formulated in Newton Raphson
J 3 J 4
polar form is given by :
Answer
A. (m n ) n
39
The per unit impedance of a 400 MVA, 200 kV/400 kV transformer is 0.1. If the Base
quantities on h.v. side of the transformer are given as 100 MVA and 100 kVA, then the per
unit impedance of the transformer on new base quantities is :
Answer
Question Cancelled
40
The inductance per loop meter of a single-phase transmission line with horizontal layout as
shown in figure below is :
D D
Answer
D. 4 10 7 ln H /m
r1 r2 0.6065 r1 r2
41
A transmission line with line impedance Z has all its line charging admittance Y placed at
receiving end. The ratio of sending end voltage to receiving end voltage under no-load
condition is :
Answer
C. 1 ZY
42
A string of 4 disc insulators has a string efficiency of 75%. If C is the capacitance between the
metal parts of the insulator and the tower structure, then the leakage current from bottom
insulator pin to ground is (Take V as rated line voltage) :
VwC
Answer
Question Cancelled
43
Identify the correct and incorrect statements, which refer to protective relays :
I. The ratio of reset to pickup value in case of electromagnetic attraction type relays is
higher than that of electromagnetic induction type relays.
II. Induction cup type relay is more sensitive than induction disk type relay, and can be
used for high speed application.
III. The actuating torque in induction type relays is proportional to cosine of the angle
between the two fluxes.
IV. The rotation of the disk in an induction disk relay, is from unshaded pole to shaded
pole.
Answer
C. II, IV are correct, but I, III are incorrect
44
Match the following properties and applications of distance relays :
(i) Impedance relay (i) Voltage restrained directional relay (i) Long length lines
(ii) Reactance relay (ii) Directional restrained over current relay (ii) Medium length lines
(iii) Mho relay (iii) Voltage restrained over current relay (iii) Short length lines
Answer
D. (i)-(iii)-(ii), (ii)-(ii)-(iii), (iii)-(i)-(i)
45
Sequence impedances of a star connected synchronous generator with neutral shorted to
ground are related to each other as :
Answer
Question Cancelled
46
The values indicated on the single line diagram, as shown below, are the reactances in per
unit on a common system base. A three phase fault occurs at point ‘ P ’ at the middle of the
line. Determine the transfer reactance between generator bus and infinite bus :
Answer
D. J 1.3
47
Identify the correct statement referring to Specific Energy Consumption (SEC) of an electric
train :
Answer
B. SEC increases with, increase in maximum speed and decrease in distance
between the stops
48
A synchronous machine under steady state has initial load angle 0 and mechanical power
input m0 as shown in below figure. A sudden increase in mechanical power input from m0
to m1 causes the rotor oscillations between points a to c on the power angle curve, then :
Answer
Question Cancelled
49
Of the following statements (i-iv) about protective devices, choose the correct option among
those listed :
(i) Interrupting rating of MCBs is upto 1800 A and that of MCCBs ranges from 10000A to
2,00,000A
(ii) The current rating of an MCB is upto 100 amperes, while an MCCB has a current
rating of between 10 to 200 amperes
(iii) MCBs contain a movable tripping circuit while MCCBs have fixed tripping circuit.
(iv) Both MCBs and MCCBs protect circuits against overloading and short circuit.
Answer
C. (i), (ii), (iv) are correct
50
Choose the right option from those listed concerning statements (i-iv) about protective
devices :
(i) RCCB disconnects an electric circuit as soon as it detects earth leakage current.
(ii) MCB affords over current and earth leakage protection.
(iii) The short circuit current rating of a 16 A, ‘C’ type MCB is approximately 10 kA.
(iv) Incorrect short circuit withstand capacity of a circuit breaker can cause fire and can be
fatal.
Answer
D. (i), (iii), (iv) are correct
51
Compute the ratio of illuminance at a point 5 metres just below a lamp emitting 100 candelas
to the illuminance at a point 5 metres away from the first point on the same horizontal
plane :
Answer
B. 2.83:1
52
An average illuminance of 50 lux is needed in a 4 metre X3 metre rectangular room.
Estimate the number of lamps each having 300 lumens to obtain the required illuminance :
Answer
A. 2
53
For the given block diagram representation of a system, evaluate C ( s) / R( s ) :
Answer
C. (G1G2 G3 ) /(1 G1H )
54
A unity feedback temperature control system has open loop transfer function
10000
G( s) . If the setpoint temperature is 500 degrees Celsius, what is
(1 s ) (1 0.5s ) (1 0.02s )
the steady state temperature in degrees Celsius?
Answer
Question Cancelled
55
The critical gain and critical frequency for the characteristic equation
4 3 2
s 22s 10s s K 0 are given by :
Answer
A. K 0.45, 0.212 rad/s
56
For a type 1 system, the intersection of initial slope of Bode plot with 0 dB axis gives :
Answer
B. Static error constant
57
Which of the following statements about compensators is correct?
(i) Due to phase lag characteristic of lag compensators, it cannot be used to improve phase
margin.
(ii) The pole and zero of lag compensator must be located substantially lower than gain
crossover frequency of the compensated system.
(iii) The main effect of lag compensator is to attenuate the high frequency magnitude
response without adding additional negative phase shift at these frequencies.
(iv) The zero of lag compensator is chosen one decade below the gain crossover frequency of
compensated system
Answer
D. (i), (ii), (iii), (iv) are correct
A 13
58
The state transition matrix of a control system is 8t 5t . The system matrix
e e e 0.5t
A is :
1 / 4 1 / 8 1 / 4 1 / 4
Answer
Question Cancelled
59
Find the state transition matrix of A .
1 3
2e t e 2t e t e 2t 2e t e 2t 2e t 2e 2t
Answer
C. t 2t
60
The state space representation of a system is given by :
x1 0 a1 0 x1 0 x1
x 2 0 0 a2 x 2 0 u, y [1 0 0] x 2
x 3 a3 0 0 x 3 1 x 3
The system is controllable for
Answer
D. a1 0, a2 0, a3
61
The state space representation of a system is given by X AX Bu, y CX , where
2 4 0
A , B , C [1 0] . The given system is :
2 1 1
Answer
C. observable and unstable
62
Find all critical points of the given system and identify their nature : x=x-y-x* +xy, y=—x?-y
Answer
A. (0, 0)-saddle, (1, —1)-stable node, (-1, —1)-unstable focus
63
Calculate the minimum sampling frequency to avoid aliasing when a continuous time signal
is given by x (t ) 5 cos 400 t :
Answer
D. 400 Hz
1 1
z (1 z 4 )
64
The Z transform of a signal is given by X ( z ) 4 . Its final value is :
(1 z 1 )2
Answer
C. 1
65
Phantom loading for testing energy meters is used :
Answer
D. To test energy meters with large current rating
66
A spring controlled moving iron voltmeter draws a current of 1 milliampere for full scale
value of 100 V. If it draws a current of 0.5 milliampere, the meter reading is :
Answer
A. 25 V
67
A clamp-on ammeter measures 50 A, when wrapped around a current carrying conductor.
If the winding turns on the jaws of the meter equal 8, what is the actual value of conductor
current?
Answer
B. 50 A
68
A single phase energy meter operating on 230 V and 5 A for 5 hours makes 1940 revolutions.
If the energy meter constant is 400, power factor of the load is :
Answer
B. 0.8
69
If the secondary winding of a current transformer is opened when the primary winding is
carrying current, which of the following occurs?
Answer
B. High induced emf is produced in the secondary winding
70
Match List 1 with List 2 :
List 1 List
Answer
D. Wein bridge (iv) Medium Q coil
71
Which of the following statements are not correct about BJT Biasing?
(i) Biasing is needed so that thermal runaway cannot take place.
(ii) Biasing is done to operate BJT in saturation region.
(iii) Fixed Bias circuit has very high stability factor so it is highly stable biasing circuit.
Answer
Question Cancelled
72
Consider the following statements :
(i) h-parameters of BJT can be used over wide range of frequencies.
(ii) h-parameters represent input resistance and output conductance when output is
shorted.
(iii) h-parameters represent forward voltage gain and reverse current gain of BJT at certain
conditions.
(iv) Input resistance of CE amplifier is high compared to CB amplifier.
(v) Output conductance of CC amplifier is high compared to CB amplifier.
Which of above statements are correct?
Answer
C. Only (ii), (iv) and (v)
73
The given oscillator circuit shown in figure is :
Answer
Question Cancelled
74
An op-amp gives triangular wave output as shown in figure for square wave input of 1 MHz
and 8 V amplitude. What is the slew rate of op-amp?
Answer
Question Cancelled
75
Consider the following statements with respect to op-amp and VCO :
(i) The input offset voltage in op-amp is due to mismatch in transistor parameters
(ii) Op-amp is a voltage controlled current source
(iii) The output frequency of VCO depends on timing resistor and inductor only
(iv) The voltage to frequency conversion factor of VCO is given by 4fo/Vcc
Which of the above statements are not correct?
Answer
B. Only (ii), (iii) and (iv)
76
The following circuit has :
(i) Unity gain
(ii) Infinite gain
(iii) High input impedance
(iv) High output impedance
(v) Zero phase shift
(vi) 180° phase shift
Which of above statements are correct?
Answer
B. Only (i), (iii) and (v)
77
To avoid race around condition occurring in J-K flipflop :
Answer
C. Propagation delay should be more than clock pulse duration and less than clock
time period
78
A 5 Bit synchronous counter uses flip-flops with propagation delay time of 20 ns each. The
maximum possible time required for change of state will be :
Answer
B. 20 ns
79
Which of the following statement about multiplexer is correct?
Answer
B. A 16 : 1 multiplexer can be implemented using four 4 : 1 multiplexers
80
An Analog to Digital Converter has a total conversion time of 125 s . What can be the
allowable highest frequency of the analog input?
Answer
B. 8 kHz
81
In a Schmitt trigger, Vsat is ± 25 V and the hysteresis width is 0.4 V. Feedback factor will be
––––––––––?
Answer
C. 0.008
82
Which of the following statements regarding sample and hold circuit is correct?
Answer
C. A good Sample and hold circuit has high input impedance and low output
impedance
83
Which of the following statements are correct about IGBT?
(i) Flow of current in IGBT is due to electrons only.
(ii) IGBT is faster than BJT and MOSFET.
(iii) On state losses of IGBT are less than MOSFET.
(iv) It has high input impedance.
Answer
A. Only (iii) and (iv)
84
A half wave thyristor converter supplies a purely inductive load. The triggering angle of
thyristor is 120°. The extinction angle will be :
Answer
C. 240°
85
Consider the following statements on triggering circuits for thyristors :
(i) RC triggering can be used for automatic control systems
(ii) The maximum firing angle is limited to 90° in R triggering circuit
(iii) UJT triggering can be used for feedback control systems
Which of the statements are correct?
Answer
A. Only (ii) and (iii)
86
A single phase full-bridge inverter using SCRs and Diodes is feeding a resistance 5 from an
input 60V DC
(i) RMS value of output voltage is 60V
(ii) Output power will be 720 W.
Answer
C. Both are correct
87
Which of the following statements is correct?
Answer
B. The ratio of reference wave voltage to carrier wave voltage is called modulation
index
88
Find the fundamental component of RMS output voltage for the following circuit :
Answer
B. 22.5 V
89
The percentage content of 7th harmonic with respect of fundamental output in single phase
inverter is :
Answer
A. 14.28 %
90
Consider the following statements :
(i) Type A chopper is also called as step-down chopper.
(ii) Type B chopper is also called as step-up chopper.
(iii) Two quadrant type A chopper always have a positive voltage.
(iv) Two quadrant type B chopper always have a positive voltage.
Which of the statements are correct?
Answer
A. Only (i), (ii) and (iii)
91
The chopper frequency of following circuit is 2000Hz. The on and off period of chopper is :
Answer
A. Ton 340.9 s and Toff 159.1 s
92
A Buck regulator, input voltage is 20V, time period is 10 seconds and duty ratio is 0.5. The
inductor and capacitors are 1 Henry and 1 Farad respectively. The peak-to-peak current
ripple of inductor will be :
Answer
C. 50 A
93
Which of the following statements about SMPS is correct?
Answer
C. In second stage of SMPS devices used are MOSFET and IGBT
94
A single-phase controlled rectifier provides an output of 100 V from an AC source of 230V.
This rectifier is driving a separately excited DC motor with armature resistance 5 ,
armature current 2A and back EMF constant 0.01V/rpm. The speed of motor is :
Answer
Question Cancelled
95
Which of the following statements are correct about interrupts in 8085 microprocessors?
(i) RST-7.5, RST-6.5, RST-4.5 and RST-5.5 are software interrupts
(ii) RST-4.5 interrupt has highest priority and only non-maskable interrupt
(iii) RST-7.5 interrupt has highest priority and only maskable interrupt
Answer
C. Only (i)
96
Consider the following statements on memories
(i) PROM is cheaper, permanent and simple to use
(ii) EPROM is used to store data for long time
(iii) EPROM is also called UV-ROM and it is permanent
Which of the above statements are correct?
Answer
B. Only (i) and (ii)
97
The 7’s compliment of octal number 6245 is
Answer
C. 1532
98
Which of the following statements is correct?
Answer
D. All the above statements are correct
99
The solution of expression A A B A C is :
Answer
C. A BC
100
Consider the following statements :
(i) IPv6 protocol has built in security
(ii) lPv6 header does not include check sum field
(iii) End to end connection integrity is achieved in both IPv4 and IPv6
(iv) The number of header fields in IPv6 is less than IPv4
Which of the above statements are correct?
Answer
B. Only (i), (ii) and (iv)
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