| Post Name | ASSISTANT ENGINEER (ELECTRICAL) (Universities in Kerala) |
|---|---|
| Question Paper Code | 023/2025 |
| Category Code | 070/2024 |
| Date of Test | 20 February 2025 |
| Medium of Question | ENGLISH |
| Exam Type | OMR Examination |
| Total Questions | 100 |
1
In the circuit below, what is the maximum power transferred to the load :
Answer
C. 20 w
2
Determine the current drawn by the circuit shown below :
Answer
B. 10 A
3
A voltage of v = 20 sin (314 t + 30Β°) is applied across an RLC series circuit, where
R =5 Ξ© , X L =25 Ξ© and X c =20 Ξ© . The current through the circuit will be :
Answer
C. 2A
4
Which of the following condition is true for both series and parallel resonance?
Answer
D. Power factor is unity
A 3
5
Calculate the form factor of the half rectified square voltage shown below :
Answer
A. 1.4
6
How much energy is stored by a 100 mH inductance with a current of 1A?
Answer
C. 0.05 J
7
A coil has an inductance of 0.35 H and is joined in series with a resistance of 110 Ξ© .
When an alternating voltage of 220 V, 50 Hz is applied to it, the wattless component of
current is :
Answer
D. 1A
8
The resistance between the terminals A and B of the circuit shown is :
Answer
B. 2 Ξ©
9
If form factor of a sinusoidal wave is 1.11, then the form factor of triangular wave will :
Answer
C. be more than 1.11
10
Dot convention in coupled circuits is used to :
Answer
A. Determine the polarity of the mutually induced voltage in coils
11
Assertion
Answer
A. : Magnetic field lines can never cross each other
Reason [R] : Magnetic field lines can never form closed loop around empty space
12
The magnetic potential due to a short dipole of the magnetic moment 2 2 Am2 at a
point 2 m away from it along the axis of the dipole is :
Answer
A. 10 β7 / 2 Tm
13
A circular loop is moving out of a uniform magnetic field region to a field free region with
a constant velocity v. The field is normal to the loop then :
Answer
B. The induced electromotive force (emf) in the loop is varying
14
A current carrying infinitely long wire is kept along the diameter of a circular wire loop
without touching it. Then correct statements are :
(I) The emf induced in the loop is zero if the current is constant
(II) The emf induced in the loop is finite if the current is constant
(III) The emf induced in the loop is zero if the current decreases at a steady state
(IV) The emf induced in the loop is finite if the current is decreasing at a steady state
Answer
C. (I), (III)
15
The current in a 0.5mH coil increases by 200 mA in 0.1 second. The induced emf will be :
Answer
D. β1 mV
16
Assertion
Answer
A. : A moving conductor in a magnetic field can be replaced by a battery of
emf e=Blv and negative terminal is that end towards which electron are
moving due to magnetic force
Reason [R] : The dynamically induced emf will exist only when, all three magnetic
field of B Wb/m2, terminal velocity of vm/s and conductor of length
1 meters are mutually perpendicular.
17
A constant current is maintained in a solenoid. Which of the following quantities will
increase if an iron rod is inserted in the solenoid along its axis?
(i) Magnetic field at the centre
(ii) Magnetic field linked with the Solenoid
(iii) Heating effect of Current
(iv) Rate of joule heating
Answer
A. (i), (ii)
18
The radius of a circular coil having 50 turns is 2cm. Its plane is normal to the magnetic
field. The magnetic field changes from 2 T to 4T in 3.14 sec. The induced emf in the coil
will be:
Answer
D. 0.04 V
19
In a composite series magnetic circuit, magnetic lines of force tend to bulge out when
crossing an air gap. This effect is known as :
Answer
B. Fringing
20
Match the similarity between magnetic and electric circuits :
Column A Column B
Answer
B. Magnetic intensity, H = NI/1 (ii) Conductance
21
The magnetic field produced by the armature of a DC generator has the following effect
on the main field flux :
Answer
D. Both demagnetisation and cross magnetisation
22
In a DC shunt motor, what happens to the speed when the load is increased from no-load
to full load?
Answer
B. Reduces slightly
23
A 220V dc series motor produces 40 Nm torque at an armature current of 10 A. When
the armature current is 20A, the developed torque will be :
Answer
D. 160 Nm
24
When the load on a single-phase transformer is increased from no-load to full load, the
core loss in the transformer will :
Answer
Question Cancelled
25
In a 11 kV/110 kV star/delta transformer, the phase transformation ratio is :
Answer
C. 10 3
26
A 4000V/400V delta-star transformer has 10A third harmonic current in all the three
secondary phases. What is the magnitude of the third harmonic line current on the
primary side?
Answer
A. Zero
27
An alternator generates 400V, 50 Hz when excited with 4A field current. Assuming the
magnetic circuit is unsaturated, the generated voltage when operating at 40 Hz and 6A
field current is :
Answer
B. 480 V
28
Two alternators are connected in parallel and equally share the load of an inductive load
connected across the pair. The excitation of one of the alternators is increased, then :
Answer
B. Its load share will increase
29
What happens when a set of equal low resistances is inserted in each phase of the rotor
circuit of a slip ring induction motor?
Answer
D. The starting torque increases
30
The input power of a three-phase, 50 Hz, 1440 rpm induction motor is 22 kW. The stator
copper loss and core loss are 1 kW each. Then the rotor copper loss will be :
Answer
A. 800 Watts
31
How many bits are required to represent a decimal number in the range from 0 to 999
using binary code? Using BCD code
Answer
C. 10, 12
32
The logic expression Y = A' B'. D0 + A' B. D1 + AB'. D2 + AB . D3 is that of
Answer
C. Multiplexer
33
Find the minterms of the following Boolean expression F ( x , y, z ) = x y + yz + xy' z :
Answer
A. Ξ£ (3, 5, 6, 7 )
34
A square wave of 1kHz is applied as the clock signal to the following circuit, Q will be a
square wave of ____________ frequency.
Answer
B. 500 Hz
35
The minimum number of flip flops needed for counting upto 300 is :
Answer
C. 9
36
How long will it take to shift an 8-bit number into an 8-bit serial input-parallel output
shift register if the clock is set at 10 MHz?
Answer
B. 800 ns
37
An 8085 microprocessor accesses two memory locations (2501 H) and (2502 H), that
contain 8-bits numbers 27 H and B1 H, respectively. The following program is executed :
LXI H, 2501 H
MVI A, 21 H
INX H
ADD M
INX H
MOV M, A
HLT
At the end of this program, the memory location 2503 H contains the number in decimal
Answer
A. 210
38
The instruction RET executes with the following series of machine cycle :
Answer
C. Fetch, read, read
39
Which stack is used in 8085 microprocessors?
Answer
B. LIFO
40
The clock frequency of an 8085 microprocessor is 5 MHz. If the time required to execute
an instruction is 1.4 ΞΌ s then the number of T-states needed for executing this
instruction is :
Answer
A. 7
41
A synchronous generator has the following parameters: synchronous reactance Xβ = 0.5 Ξ©, rated voltage V = 220 V. Field excitation is adjusted so that the generator operates at 180Β° power angle. The generator is delivering power to a load with a power factor of 1.0. Calculate the power output of the generator at a power angle of Ξ΄ = 30Β°?
Answer
A. 48.4 KW
42
Alternator is rated as 150 MVA, 11 kV, X = 1.2 Pu. What will be the PU reactance at
250 MVA and 13.2kV :
Answer
Question Cancelled
43
A synchronous generator is connected to an infinite bus through a transmission line. The
pre-fault power transfer is P = 0.5 Pu, and the maximum power transfer capability is
Pmax = 1.5 pu . A fault reduces Pmax to 0.3 pu. Determine if the system remains stable if
the fault is cleared in time to restore Pmax to 1.5 Pu. Use the equal area criterion.
Answer
A. The system is likely unstable, depending on fault clearing time
44
A 3- Ο , 11kV oil circuit breaker is rated 600A, 1000 MVA, 3sec. The symmetrical
breaking current is :
Answer
D. 52.48 kA
45
A single line-to-ground (LG) fault occurs at a bus with the following sequence
impedances:
Z1 = 0.3 pu, Z2 = 0.4 pu, Z0 = 0.2 Pu.
The pre-fault voltage is 1 pu. Calculate the fault current and voltage of the faulted
phase.
Answer
A. I f = 3.33 pu, V f = 0 v
46
A 100 MVA, 20 kV generator is subjected to a three-phase fault at its terminals. The
generator has a sub-transient reactance X"=0.25 Pu. Calculate the fault current ( I f )
during a three-phase fault.
Answer
C. 11.54 kA
47
In a five-unit insulator string, voltage across the lowest unit is 17.5 kV and string
efficiency is 85.24%. The total voltage across the string will be equal to :
Answer
D. 74.58 kV
48
A 50 Hz, 4-pole synchronous generator has a moment of inertia (H) of 5 MJ/MVA. The
generator operates at 100 MVA and 0.8 power factor lagging. If a disturbance causes a
sudden load rejection of 25 MW, determine the initial acceleration of the rotor in
electrical degrees per second squared. Assume no damping :
Answer
B. 143.24Β°/sec2
49
A synchronous generator has the following parameters: rated voltage V = 500 V, synchronous reactance Xβ = 0.8 Ξ©, power angle Ξ΄ = 60Β°. The generator delivers a load with a power factor of 0.8 (lagging). Calculate the power delivered by the generator at a power angle of Ξ΄ = 60Β°.
Answer
A. 270.6 KW
50
A synchronous generator has the following parameters:
Rated voltage V = 400 V, Synchronous reactance X_s = 1.2 Ξ© . The generator operates at
a power angle Ξ΄ = 45Β°. The field excitation is adjusted so that the generator delivers a
maximum power. Calculate the maximum power the generator can deliver.
Answer
C. 133.33 KW
51
C
The ratio from the given signal flow graph is :
R
G1 G2 G3 G4
Answer
C. 1 β G3 G4 H1 + G2 G3 H 2 + G1 G2 G3 G4 H 3
G1 G2 G3 G4
52
= 2 where Ξ© (t ) represents angular velocity and ei (t ) represents a
Ei (s ) s + 14 s + 100
constant voltage of amplitude A volts. The steady state response of angular velocity will
be :
Answer
C. A
53
The damping ratio of a second order system whose closed loop transfer function is given
10000
by 2 is :
s + 140 s + 10000
Answer
D. 0.7
54
The steady state error in the unit step response for the system represented in figure
below is:
Ris) 4 6% 0.3 st1 10 C(s)
2 0.5 st1 sβ+2s+5
1 1
Answer
D. 11 21
55
By what factor should gain K be multiplied for the damping ratio to be increased from
K /T
0.2 to 0.8 in the closed loop transfer function given by ?
S K
S2 + +
T T
1 1
Answer
D. 8 16
56
For a critically damped system the nature of roots is :
Answer
D. Real and repeated
57
The open loop transfer function with s=jw is obtained as
G (jw) H( jw)=ββββ__* The value of k corresponding to gain margin
~0.25w? + jw(l-0.01w?)
of 20 dBis :
Answer
B. 2.5
58
If gain k is increased from 100 to 1000 in the system closed loop transfer function
k
2
:
s + 10 s + k
Answer
C. Damping ratio reduces but natural frequency increases
59
The steady state output corresponding to unit step input for a system whose forward
20
path transfer function is 2 and feedback path transfer function is (s + 5) is :
s
Answer
C. 0.2
60
The value of gain K satisfying K v > 10 sec β1 and stable closed loop operation for a unity
K
feedback system with G (s ) = is :
s (s + 2)(s + 10 )
Answer
D. None of the above
61
Anode current of a thyristor is given by,
Answer
A. ssume two transistor model of thyristor]
Note :
Ξ± β Current gain
IG β Gate current
I co β Leakage current
Ξ± 2 I G + I co1 + I co2 Ξ± 2 I co1 + I co2 β I co1
62
Displacement angle of third harmonic in a single phase full converter for an firing angle
of 15Β° will be :
Answer
C. 45Β°
63
Ripple frequency of three phase full converter operating at 60 Hz will be :
Answer
D. 360 Hz
64
Effective input resistance of chopper (step down) operating with resistive load (R Ξ© )
will be :
Answer
D. uty cycle Γ R) Ξ©
65
Which PWM will have better DC bus utilisation?
Answer
C. SVPWM
66
Drives used for pressing operation can be classified as :
Answer
A. Intermittent periodic duty
67
A DC shunt motor drives a constant load whose torque is constant. When the applied
voltage is reduced to half of the rated voltage, new armature current will be :
Answer
C. Twice the rated current
68
In the figure shown below, find the relation between the resistances R1 ,R2 and R3 :
Torque
Fig : Speed-Torque relationship for different external resistances connected.
Answer
C. R1 < R2 < R3
69
Effective input impedance of an ideal Op-Amp will be (measured directly at the inverting
terminal) :
Answer
C. Infinity
70
Mechanism which sets an upper limit to the rate at which the output voltage of an
op-amp can change is :
Answer
C. Slew rate
71
A practical voltmeter has a finite resistance. What is the impact of this on the
measurement?
Answer
B. It results in the voltmeter displaying a voltage that is less than the actual
voltage
72
A moving iron ammeter is used to measure the current i (t ) = 1 + 4 sin Οt . The reading of
the ammeter is :
Answer
C. 3A
73
The current flowing through a moving iron ammeter is reversed without changing its
magnitude. Then :
Answer
C. The ammeter pointer deflects in the same direction and reads the same
current
74
What current would flow through a PMMC ammeter which has a coil of 100 turns, flux
density of 0 .1 web / m2 , area of cross section of 50mm2 if the pointer deflecting torque is
2 Γ10β3 Nm ?
Answer
D. 4A
75
Which of the following types of instrument(s) is
Answer
A. re) used exclusively for
DC measurements?
(i) PMMC type
(ii) Electrolytic type
(iii) Dynamo type
(iv) Moving iron type
76
In an unbalanced three-wire system, the minimum number of wattmeters that are
necessary to measure power is :
Answer
B. Two
77
The ratio of the readings from the two Wattmeters employed to measure power in a
balanced three-phase load is 3 + 1 : 3 β 1 . What is the power factor of the load?
Answer
C. 0.707
78
An induction type energy meter with a meter constant of 500 revolutions per
kilowatt-hour, working at 250 volts and 10 amperes for 4 hours, completes
2000 revolutions. The load power factor is :
Answer
D. 0.4
A 17 023/2025
79
To calculate power factor using a digital energy meter, the meter constantly samples the
instantaneous voltage and currents and then requires :
(i) Calculation of average value of product of instantaneous voltage and currents over
a period of time T where T is the time period of the a.c. waveform
(ii) Calculation of time at which maximum and minimum voltages occur
(iii) Calculation of maximum voltage and maximum current
Answer
C. Options (i) and (iii)
80
A CRO is used to monitor the output of a circuit. The display exhibits a sustained sine
wave characterized by a peak-to-peak amplitude of 6 divisions. What is the peak voltage
of the signal if the vertical sensitivity is adjusted to 5V/div and the horizontal time base
is set to 10 ms/div?
Answer
B. 15 V
81
The transfer function of a zero-order hold circuit for a sampling frequency of
n samples/sec is given by :
ο¦sοΆ
βο§ ο·
sn ο¨nοΈ
1βe 1βe
Answer
D. sn s
82
The following figure represents a continuous-time signal, x (t ) vs time (t) in seconds,
then x (t ) can also be represented using unit steps signal, u (t ) as :
Answer
C. 2u (t ) β 2u (t β 1)
83
Figure
Answer
A. represents a continuous-time signal, x (t ) vs time (t) in seconds, and Figure
84
Let x (t ) and y(t ) represents the input and output of a system respectively. Also, the
input-output relationship of the system is given by
y (t ) = x (t ) + x (t + 5) + x (t β 10 )
then the system is :
Answer
A. Linear
85
Let x (t ) and y (t ) represents the input and output of a system respectively. Also, the
input-output relationship of the system is given by
y (t ) = t sin(x (t ))
then the system is :
Answer
C. Both
86
The discrete-time signal x(n) = sin[(7Ο/4)n] is:
Answer
B. a periodic signal with fundamental period 8
87
For a signal,
x (t ) = cos (2 t ) + sin (4 t ) cos (4 t )
if x e (t ) and x 0 (t ) represents its odd and even components, then x e (t ) and x 0 (t ) will be
Answer
B. x e (t ) = sin (4 t ) cos (4 t ) x 0 (t ) = cos (2t )
88
A signal x (t ) = 10 sin (400 Ο t ) is to be sampled and converted into discrete form, if so
among the following options which sampling frequency will ensure that x (t ) can be
uniquely recovered from its samples?
Answer
B. 500 Hz
89
Which of the following statement about a signal, x (t ) is correct?
Answer
D. The signal will be an energy signal if the total energy of the signal is finite
and time-averaged power is zero
023/2025 20 A
90
What will be the output, y (n ) when y (n ) = u (n )Ξ΄ (n ) where u (n ) is the discrete unit step
and u (n ) is the discrete unit impulse?
Answer
C. Ξ΄ (n )
91
An LVDT transducer is used to measure displacement in a robotic arm. If the primary
winding voltage decreases by 10%, how does it affect the sensitivity of the output voltage
in the presence of external electromagnetic interference?
Answer
C. Sensitivity decreases, and output becomes nonlinear
92
A Hall-effect sensor is calibrated for a magnetic field of 0.5 T, producing an output
voltage of 25 mV with a supply current of 2 A. If the magnetic field increases to 0.8 T and
the current decreases to 1.5 A, what is the new output voltage?
Answer
A. 30 mV
93
A battery pack consists of 4 cells, each rated at 3.7 V, 2500 mAh, connected in a 2S2P
configuration. What is the total voltage and capacity of the pack?
Answer
C. 7.4 V, 5000 mAh
94
What happens to the capacity and voltage of a battery system when connected in
parallel?
Answer
B. Voltage remains constant, capacity increases
95
In a high-rise building, the earthing system is connected to multiple points on the
buildingβs metal framework. Why is this practice followed?
Answer
B. To ensure equipotential bonding throughout the structure
96
A domestic wiring system uses a radial circuit to supply kitchen appliances with a
maximum load of 2.5 kW at 230 V. If the circuit is protected by a 16 A circuit breaker,
which of the following rules ensures the breaker does not trip?
Answer
D. The appliances must have a combined power factor of 0.8 or higher
97
A room has three light fixtures rated at 40 W each, connected to a 230 V supply via a
2 mm2 copper wire (resistance = 0.008 Ξ© /m) with a total wire length of 20 m (round trip).
Calculate the voltage drop in the wire.
Answer
B. 0.0835 V
98
A rotary angular displacement transducer has a total angular range of 360Β° and a linear
output characteristic. It is supplied with a voltage of 12 V. If the output voltage is
measured as 8 V, what is the corresponding angular displacement of the shaft?
Answer
C. 240Β°
99
An incandescent lamp operates at 60 W and has a luminous efficacy of 15 lm/W, while an
LED lamp operates at 15 W and has a luminous efficacy of 60 lm/W. What is the ratio of
the total luminous flux emitted by the LED to that of the incandescent lamp?
Answer
A. 1:1
100
In a workspace with high ceilings, which lighting source is most efficient for uniform
illumination?
Answer
D. LED lamps
ββββββββ
023/2025 22 A
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