| Post Name | SUB-ENGINEER (Local Self Government (Electricity wing of Thrissur)) |
|---|---|
| Question Paper Code | 074/2026 |
| Category Code | 770/2025 |
| Date of Test | 3 August 2026 |
| Medium of Question | ENGLISH |
| Exam Type | OMR Examination |
| Total Questions | 100 |
1
The distance between two magnetic poles is doubled and their pole strengths are
also doubled. The force between them is
Answer
B. Remains unchanged
2
The strength of an electromagnet is determined by
Answer
D. all of the above
3
a capacitor of 10 µF charged to 400 V is connected in parallel with another capacitor
of 5 µF capacitance and charged to 100 V. The common potential is
Answer
A. 300 V
4
When the relative permeability of a material is much greater than one, it is
Answer
C. Ferromagnetic
5
a resistor of 6 Ω is connected in series with parallel combination of a number of
resistors, each of 6 Ω. If the total resistance of the circuit is 7 Ω. The number of
resistors in parallel is
Answer
A. 6 Ω
6
In any electrical network, the algebraic sum of the currents meeting at a point is zero.
The statement is associated with
Answer
D. Kirchhoff’s current law
7
a circuit has inductance of 3 H. If the circuit current changes at the rate of 15 a /second.
Then self induced e.m.f. is
Answer
B. 45 V
8
a heater coil rated at 1000 W 200 V is connected to 100 V. Power consumed is
Answer
C. 250 W
9
A conductor of length 2 meter moves at right angle to a uniform magnetic field of flux
density 1.2 Weber/meter square with a velocity of 30 meter/second. The induced
e.m.f. when the conductor moves at an angle of 30 degree to the direction of field is
Answer
D. 36 V
10
Each question is provided with four choices
Answer
B. ,
11
The input ac supply commonly used in a regulated power supply is
Answer
B. 230 V, 50 Hz
12
lVdT is used to measure
Answer
C. linear displacement
13
The basic blocks of a dc power supplies are
Answer
A. Transformer, Rectifier, Filter, Regulator
14
a fuse protects against
Answer
B. Over current
15
For proper transistor operation, the Emitter-Base junction should be _______ and
the collector-Base junction to be __________.
Answer
B. Forward biased and Reverse biased
16
Thermal runaway is mainly caused by
Answer
B. Increase in temperature
17
The main purpose of an optocoupler is
Answer
B. Isolation
18
Heat in induction heating is produced by
Answer
A. Eddy currents
19
Biasing sets the transistor operating point near the middle of the
Answer
C. dc load line
20
Online UPS provides
Answer
B. Zero transfer time
21
What tool is used to check if a circuit is energized without making physical contact
with the wire ?
Answer
B. Non-contact voltage tester
22
What does the “lockout/Tagout” (lOTO) safety procedure prevent ?
Answer
B. accidental re-energization of equipment under repair
23
ln a purely capacitive circuit, the alternating voltage _______ the alternating current by 90°.
Answer
A. lags
24
What is the immediate primary consequence of connecting two batteries with different
voltage ratings in parallel ?
Answer
C. A massive circulating loop current flows from the higher-voltage battery into the
lower-voltage battery, causing severe overheating and risk of damage
25
an electric scooter needs a 36 V battery pack using standard 3.6 V lithium-ion cells.
Each cell has a capacity of 2.5ah. lf the scooter requires a total pack capacity of
10ah, what is the exact total number of individual cells needed to build this pack ?
Answer
D. 40 cells
26
lf a sinusoidal ac voltage has a peak value of 100 V, what is its approximate
Root-mean-Square (RmS) voltage ?
Answer
C. 70.7 V
27
For the AC voltage v = 200 sin(314t), what is the average voltage over one half-cycle?
Answer
A. 127.4 V
28
a balanced delta load has an impedance of 10 Ω per phase and is connected to a
3-phase line voltage of 200 V. What is the line current ?
Answer
D. 34.64 a
29
For a waveform, the RmS voltage is 12 V and the half-cycle average voltage is 9 V.
What is the form factor of this specific waveform ?
Answer
B. 1.33
30
a capacitive reactance of 10 Ω is operating on a 50 Hz system line. If the line frequency
changes to 100 Hz, what is the new capacitive reactance value ?
Answer
A. 5 Ω
31
The slew rate of an operational amplifier is defined as the
Answer
B. The maximum rate of change of the output voltage with respect to time
32
Find the output voltage (Vout) when the input voltage (Vin) is 2V.
+15V
–
+ Vout
Vin –15V
Answer
D. 2V
33
The output of an OPamP differentiator circuit for a sine wave input is
Answer
B. cosine
34
Which of the following is an application of a Schmitt trigger circuit ?
Answer
A. converting an irregular shaped waveform into a square waveform
35
How many comparators are required for a flash-type Analog-to-Digital
converter
Answer
C. 15
36
In a Phase-locked loop (Pll), the range of frequencies over which the Pll can
maintain lock with the incoming signal is called
Answer
C. lock range
37
Identify the 555-timer pin that should be connected to power supply (+Vcc) when left
unused to maintain normal operation.
Answer
B. Reset
38
Which principle specifies the necessary condition for sustained oscillations in a linear
sinusoidal oscillator ?
Answer
A. Barkhausen criterion
39
Which of the following is a non-sinusoidal oscillator ?
Answer
B. astable multivibrator
40
among the following, which oscillator has the greatest frequency stability ?
Answer
C. crystal oscillator
41
In a full wave rectifier circuit, what is the primary purpose of adding a capacitor filter
across the output load ?
Answer
D. To reduce the ripple factor and smooth out the pulsating dc output
42
Which power electronic device is structurally equivalent to two ScR connected in
inverse parallel, making it ideal for ac power control ?
Answer
C. Triac
43
Which protective device detects leakage current and disconnects the supply ?
Answer
B. RccB
44
an ScR can be turned on by
Answer
B. applying a gate pulse while forward biased
45
In a UJT relaxation oscillator, the frequency of oscillation mainly depends upon
Answer
A. charging resistance and capacitor values
46
Two identical diodes are used in a center tapped full wave rectifier. If one diode
becomes open circuited, the output will behave like
Answer
C. A half wave rectifier
47
In a plate earthing system, adding water around the earth pit mainly helps to
Answer
C. Improve conductivity between electrode and soil
48
an electric iron and a water heater cause the fuse to blow whenever they are operated
simultaneously. The most likely reason is
Answer
B. circuit overload
49
a dPST switch is commonly used when it is necessary to
Answer
D. disconnect both phase and neutral simultaneously
50
an IGBT is selected instead of an ScR for a high frequency switching application
mainly because
Answer
A. IGBTs can be switched ON and OFF more easily by control signals
51
convert hexadecimal number 2a2 to decimal number.
Answer
B. 674
52
The 5 bit Gray code representation of the binary 10111 is
Answer
C. 11100
53
The Boolean function a+Bc is a reduced form of
a)
Answer
A. +B).
54
The Carry flag
Answer
A. PSW.7
55
Why are Schottky transistor preferred over normal bipolar transistors in digital logic
circuits like TTl ?
Answer
D. They completely eliminate saturation delay time by preventing deep saturation
56
How many address lines and data lines are required for a memory chip designed as
4K × 16 ?
Answer
C. 12 address lines, 16 data lines
57
A flip flop has its input T tied steadily to logic 1. If a continuous clock signal with a
frequency of f is applied, what will be the frequency of the output signal at Q ?
Answer
D. f/2
58
a digital design requires a 3 input aNd gate, but only 2 input NaNd gates are available
in the inventory. What is the minimum number of 2 input NaNd gates required to
build this 3 input aNd gates logic function ?
Answer
C. 4
59
Why does a standard SRAM cell maintain its data state indefinitely as long as power
is applied without requiring any refresh operations ?
Answer
D. It uses a cross-coupled inverter latch structure that provides continuous
regenerative feedback to lock the state
60
A 5 V CMOS gate drives a standard 5 V TTL gate. CMOS: Vₒₕ(min) = 4.4 V, Vₒₗ(max) = 0.3 V; TTL: Vᵢₕ(min) = 2.0 V, Vᵢₗ(max) = 0.8 V. What is the low-level noise margin Vₙₗ?
Answer
B. 0.5 V
61
If the armature winding of an alternator is short-pitched by an angle of 30° the Pitch
factors is
3
Answer
B. 0.9659
62
In the torque (T) versus slip (s) characteristics of a three-phase induction motor, the unstable region is where
Answer
A. T ∝ 1/s
63
Kramer system of speed control is used only for
Answer
C. Slip ring induction motor
64
For the rotor of a double-cage induction motor
Answer
D. The outer cage has high resistance and low inductance
65
Property of ferromagnetic materials to change its shape or dimensions when it is
subjected to cycle of magnetization is called
Answer
C. magnetostriction
66
The critical field resistance in a DC shunt motor is
Answer
A. Maximum field circuit resistance above which the generator fails to self-excite and
build up voltage
67
The fact that a single-phase induction motor is not self-starting can be well
demonstrated by
Answer
B. double Revolving Field Theory
68
The maximum load torque a synchronous motor can develop at rated voltage and
frequency without losing synchronism is
Answer
D. Pull-out torque
69
When a 3 phase alternator is synchronized with existing busbar using three dark
lamp method, the higher flickering frequency of the lamps indicates
Answer
C. The difference in frequency of busbar and the incoming alternator is higher
70
When ideal transformer is on no-load the angle between primary current and input
voltage phasors is
Answer
C. 90°
71
A specific colour is represented by the primary colour voltages: Red = 0.7 volts,
Green = 0.2 volts and Blue = 0.5 volts. Which of the following statements is correct
regarding this colour ?
Answer
D. The white light content is determined by Green = 0.2 volts and the luminance
signal is 0.383 volts
72
Consider the following statements regarding colour picture tubes :
I. delta-gun picture tube employs three separate electron guns, one for each
colour signal. The guns are positioned at the vertices of an equilateral
triangle and are tilted inward toward the tube axis.
II. a Trinitron picture tube employs a single electron-gun assembly with three in-line
cathodes and the phosphors on the screen are arranged as vertical strips.
Which of the following is correct ?
Answer
A. Both statements I and II are correct
73
In a Pal-d colour television receiver, which of the following statements correctly
describes the nature of the signals present at the outputs of the adder and subtractor
matrix circuits ?
Answer
B. The adder consistently produces 2U, while the subtractor output alternates in
polarity between + 2jV and – 2jV on successive lines
74
Which of the following correctly represents the signal flow in a satellite television
receiving system from transmission to display ?
Answer
B. Satellite → dish antenna → lNB → Set top box → Television
75
Which of the following correctly differentiates maTV and caTV systems based on
their typical area of coverage ?
Answer
C. maTV serves a building complex, whereas caTV serves a large subscriber
community
76
Consider the following statements regarding modulation :
I. In amplitude modulation, the rate at which the carrier amplitude varies is determined
by the frequency of the modulating signal.
II. In frequency modulation, the rate at which the carrier frequency varies is
determined by the frequency of the modulating signal.
Which of the following is correct ?
Answer
D. Both statements I and II are correct
77
In a Frequency modulation system, a 500 Hz modulating signal with an amplitude
of 1.6 V produces a modulation index of 50. If the modulating frequency drops to
200 Hz and the amplitude increases to 3.2 V, the resulting maximum frequency
deviation and the new modulation index are respectively
Answer
C. 50 kHz and 250
78
Fill in the blanks with the correct option :
The signal obtained by sampling a continuous analog waveform is represented using
__________. If these samples are further quantized and encoded into a binary digital
bit stream, the system is referred to as __________.
Answer
B. Pulse amplitude modulation; Pulse code modulation
79
consider the following statements.
I. Thermal noise is caused by the random vibration of charge carriers as a function
of temperature.
II. Shot noise disappears when a steady dc current is established in a device.
III. Transit time noise is negligible at low frequencies and becomes significant at
high frequencies.
Which of the following is true about these statements ?
Answer
C. Only I and III are true
80
Which of the following statements best defines the radiation resistance of an antenna ?
Answer
D. It is an equivalent resistance that would dissipate the same amount of power as
that radiated by the antenna
81
Energy meter is an example of
Answer
C. Integrating instrument
82
Three-phase power can be measured using
Answer
D. all of the above
83
The essential elements of an electronic instrument are
Answer
D. all of the above
84
TOd meter stands for
Answer
A. Time of day meter
85
Find the multiplying factor of a shunt of 500 ohm resistance used with ammeter of
1500 ohm resistance.
Answer
C. 4
86
dual Trace cRO uses
Answer
A. One beam
87
a triangle waveshape is obtained by
Answer
B. By Integrating a square wave
88
Which parameter is critical for avoiding aliasing in data acquisition ?
Answer
C. Proper sampling rate
89
current Transformer
Answer
A. Step down high current
90
Synchroscope is used for
Answer
B. Synchronizing two alternators
91
What is the bit size of the dPTR register in the 8051 microcontroller ?
Answer
C. 16 bits
92
Which of the following is the general-purpose of Ram area in 8051 microcontroller ?
Answer
A. 30H to 7FH
93
Which flag in the PSW register of 8051 is set when a carry is generated from bit 3
to bit 4 during an arithmetic operation ?
Answer
D. ac
94
an 8051 microcontroller has its Ea pin tied to ground. during an instruction fetch,
from which memory space will the microcontroller retrieve the opcode ?
Answer
B. External ROm only
95
Which type of output latch is associated with each port pin of 8051 ?
Answer
C. d latch
96
In an 8051 microcontroller, how the Timer 1 functions when it is programmed to
operate in mode 3 ?
Answer
C. It holds its count and stops counting
97
The crystal frequency of an 8051 microcontroller is 12mHz. What will be the baud
rate if the serial port is configured to operate in Mode 0 ?
Answer
B. 1 mbps
98
Which of the following ‘instruction – addressing mode’ combination is correct ?
Answer
D. mOV a,@R0 – Indirect addressing mode
99
Which register in 8051 microcontroller does not have an internal address ?
Answer
B. Pc
100
Immediately following a hardware reset, what value is automatically loaded into the
8051 port latches ?
Answer
A. FFH
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