| Post Name | DRAFTSMAN GRADE I (ELECTRICAL) - KERALA WATER AUTHORITY |
|---|---|
| Question Paper Code | 164/2025 |
| Category Code | 031/2024 |
| Date of Test | 3 December 2025 |
| Medium of Question | ENGLISH |
| Exam Type | OMR Examination |
| Total Questions | 100 |
1
The effect of rise in temperature is :
Answer
D. None of the above
2
The main characteristics of a series circuit :
Answer
C. Both
3
A circuit has two parallel resistors : 30 Ω and 150 Ω. The current through the 30 Ω
resistor is 10 A. Find the resistance of a third resistor to be added in parallel so that the
total current becomes 18 A.
Answer
A. 50 Ω
4
At a node, two unknown currents meet along with a known current of 7 A entering. If
the two leaving currents are 2 A and 5 A respectively, what is the net current entering or
leaving the node?
Answer
A. 0 A
5
A 1.5 kW heater operates for 4 hours daily. How many units of electricity does it
consume in 30 days?
Answer
A. 180 kWh
6
The product of electric field intensity at any point within a dielectric medium and the
absolute permittivity at the same point is called :
Answer
B. Electric Displacement
7
Which of the following is correct?
Answer
B. Current in the capacitor is present only when voltage on it changes with time
8
The SI unit of magnetic permeance is :
Answer
C. Henry
9
A coil of resistance 100 Ω and 200 turns is placed in a magnetic field of 2 mWb.
A galvanometer of resistance 200 Ω is connected in series with the coil. If the coil is
moved in 0.2 seconds from the given field to a field of 0.5 mWb, calculate the average
induced e.m.f. and the current.
Answer
D. 1.5 V and 5 mA
10
Two coils have self-inductances of 100 mH and 150 mH. When connected in series aiding,
the total inductance is 250 mH. What is the coefficient of coupling between the coils?
Answer
B. 0
11
The resistivity of a semiconductor ___________ with increase in temperature.
Answer
B. Decreases
12
The process of adding impurities to a pure semiconductor to increase its conductivity is
called :
Answer
D. Doping
13
Zener diode works in which region?
Answer
B. Reverse breakdown region
14
The efficiency of a half-wave rectifier is approximately :
Answer
A. 40.6%
15
The voltage gain of a common-emitter amplifier is :
Answer
A. High
16
Thermal runaway is due to :
Answer
D. Increase in leakage current with temperature
17
The gate-to-source voltage that makes the drain current zero is called :
Answer
B. Pinch-off voltage
18
The MOSFET is controlled by :
Answer
B. Voltage
19
A 7909 voltage regulator provides an output of :
Answer
C. –9 V
20
The device that can control power in one direction only is :
Answer
C. SCR
21
In an AC circuit containing resistance and inductance, the power factor is given by :
Answer
A. R/Z
22
If frequency of supply is doubled, the reactance of a pure capacitor will :
Answer
C. Become half
23
In star connection, each phase has a voltage of 230 V. Then calculate the line voltage.
Answer
B. 398.36 V
24
Calculate the RMS value of a sinusoidal current with a peak value of 10 A.
Answer
B. 7.07 A
25
Which of the following is the first step in providing first aid for an electric shock victim?
Answer
C. Switch off the power source
26
The form factor of an alternating current waveform is the ratio of :
Answer
B. RMS value to average value
27
The watt-hour efficiency of a lead-acid cell is generally :
Answer
D. Lower than ampere-hour efficiency
28
What is the colour code for an earth wire in electrical installations?
Answer
C. Green
29
The primary purpose of earthing in electrical installations is to :
Answer
B. Provide a low-resistance path for fault currents
30
Calculate the total number of cells required in a solar PV system with 48V DC and
300 Ah. Each battery cell is 2 V, 150 Ah :
Answer
C. 48
31
Which IC can be used a Voltage Controlled Oscillator (VCO)?
Answer
C. LM 566
32
In a practical differentiator, a small resistor is often added in series with the input
capacitor to :
Answer
B. Prevent oscillation and reduce high-frequency noise
33
In a Colpitt’s oscillator, the feedback is derived from
Answer
B. Capacitive voltage divider
34
Which ADC type is generally the fastest?
Answer
D. Flash
35
In a successive approximation type ADC, the conversion time for an n-bit converter is :
Answer
B. Proportional to n
36
In a differential amplifier, a high CMRR is desirable because it means the amplifier :
Answer
B. Can reject noise common to both inputs effectively
37
The primary function of a Schmitt Trigger is to :
Answer
C. Convert a noisy signal into a clean square wave
38
The input bias current of an op-amp is defined as the :
Answer
B. Average of the two input base currents
39
The primary function of the three op-amp configuration in an instrumentation amplifier
is to provide :
Answer
B. High input impedance and high CMRR
40
The purpose of a precision rectifier over a standard diode rectifier is to :
Answer
C. Eliminate the diode forward voltage drop error
41
Which of the following statement/s is/are true regarding PVC conduit wiring?
(i) Conduit size is stated in terms of inner diameter.
(ii) It provides protection against mechanical damage.
Answer
C. Only (ii) is true
42
What is the approximate nominal cross sectional area of a multistranded wire with
following specifications 3/0.925?
Answer
A. 2
43
Which of the following statement/s is/are true regarding HRC fuse?
(i) It requires replacement after each operation.
(ii) Interlocking is possible in these types of fuses.
Answer
B. Only (i) is true
44
Which of the following statement/s is/are true regarding plate earthing?
(i) The advantage of plate earthing is that the discontinuity of earth wire with plate
can be observed physically.
(ii) Earthing plate is surrounded by alternate layers of salt and charcoal to reduce
earth resistance.
Answer
C. Only (ii) is true
45
Which of the following statement/s is/are true regarding MCB?
(i) MCBs are connected in series with phase wire.
(ii) The thermal overload protection in a MCB is achieved with a solenoid operating
a plunger.
Answer
B. Only (i) is true
46
Which of the following statement/s is/are true regarding full wave diode rectifier with
centre tapped transformer?
(i) Peak inverse voltage of diode used is less compared to that of diode used in half
wave rectifier.
(ii) The output voltage has more ripple content compared to half wave rectifier.
Answer
D. Both (i) and (ii) are false
47
Which of the following statement/s is/are true regarding UJT relaxation oscillator
employing an RC circuit?
(i) The discharge time of the capacitor is made larger compared to the charging time.
(ii) The width of the output pulse can be varied by varying the resistance or
capacitance.
Answer
B. Only (ii) is true
48
Which of the following statement/s is/are true regarding IGBT?
(i) It has a lower conduction drop like a power transistor.
(ii) It has a high input impedance like power MOSFET.
Answer
A. Both (i) and (ii) are true
49
Which of the following statement/s is/are true regarding TRIAC?
(i) It is a bidirectional thyristor.
(ii) It has three terminals.
(iii) It is used widely for control of power in AC circuits.
Answer
D. (i), (ii) and (iii) are true
50
Match the following components of a UPS to their functions :
(1) Battery charger (i) Converts AC to DC
(2) Inverter (ii) Converts DC to AC
(3) Static contactor (iii) Connects load from inverter to
alternate AC supply
Answer
C. (1)-(i), (2)-(ii), (3)-(iii)
51
The Gray code equivalent of binary 101 is :
Answer
B. 111
52
How many distinct values can be represented using an 8-bit binary number?
Answer
C. 256
53
The binary value 1 represents which logic level?
Answer
A. High
54
The Boolean expression A + A B simplifies to :
Answer
C. A+B
55
How many flip-flops are required to design a 4-bit counter?
Answer
D. 4
56
What is the size of the program counter in 8051?
Answer
C. 16-bit
57
Which logic family is most suitable for implementing complex digital systems like
microprocessors?
Answer
D. VLSI
58
The fan-out of a TTL gate is usually :
Answer
A. 10
59
Which logic family generally has the lowest static power dissipation?
Answer
B. CMOS
60
Which memory has the fastest access time?
Answer
B. SRAM
61
The armature core of a DC Machine is made of _____________ material.
Answer
B. Silicon Steel
62
The number of parallel paths in a Wave Wound 8 pole DC Generator?
Answer
A. 2
63
The material used for the commutator :
Answer
D. Copper
164/2025 12 A
64
The front pitch of a 4 pole 24 slots Single Layer Lap Winding of a DC Generator is :
Answer
B. 6
65
In a Lap Winding, the number of brushes are equal to :
Answer
B. Poles
66
The generating voltage at the generating station in Kerala is :
Answer
A. 11 KV
67
An AC Induction Motor has :
Answer
C. Slip
68
What is the frequency of AC supply in most house hold electrical system in India?
Answer
C. 50 Hz
69
Why do Single-Phase Induction Motors require an auxiliary winding?
Answer
D. To create a rotating magnetic field and provide starting torque
70
The motor which can be used in both AC and DC supply is generally known as?
Answer
A. Universal Motor
71
In a TV receiver, the color killer :
Answer
A. cuts off the chroma stages during monochrome reception
72
In radio broadcasting, rhombic antennas are used for :
Answer
B. long distance directional broadcasting
73
The value of a resistor creating thermal noise is doubled. The noise power generated is
therefore :
Answer
D. unchanged
74
Bandwidth occupied by 100 MHZ carrier, AM modulated by signal frequency of 10 KHZ
is :
Answer
B. 20 KHZ
75
The positive peak of an AM wave is 16V and the minimum value is 4V. Assuming single
tone modulation, the modulation index is :
Answer
A. 0.6
76
In a television camera tube, scanning of a picture is done :
Answer
A. Line by line from left to right
77
The decoder for PAL system is :
Answer
C. Similar to NTSC decoder supplemented by 64 ms delay line and an electronic
commutator
78
Which one of the following is non-resonant antenna?
Answer
D. Rhombic antenna
79
In PCM, the quantization noise depends on :
Answer
C. No. of quantization level
80
The modulation technique most affected by noise is :
Answer
A. ASK
81
Consider the following statements :
(i) Moving iron power factor meters are commonly used rather than electrodynamic
type of meters.
(ii) Moving iron power factor meters are more prone to errors compared to
electrodynamic type of meters.
Which of the statement is/are CORRECT?
Answer
C. Both (i) and (ii)
82
When the current through the operating coil in a moving iron instrument gets doubled,
the initial operating torque :
Answer
B. Increases four times
83
Consider the statements in three phase power measurement using two wattmeter
method :
(i) The power factor is unity when both wattmeters has identical readings.
(ii) The power factor is unity when one of the wattmeters reads zero.
(iii) The power factor is 0 when both wattmeters read same and one wattmeter gives a
negative reading (W1 = –W2)
Identify the Correct statements :
Answer
D. Only (i) and (iii)
164/2025 15 A
84
In an electro dynamo meter wattmeter, the pressure coil is :
Answer
C. Highly resistive
85
Which of the following statement/s is/are True about a current transformer?
(i) The primary winding has few turns.
(ii) The secondary winding has few turns.
(iii) The primary winding has large number of turns.
(iv) The secondary winding has large number of turns.
Answer
B. Only (i) and (iv)
86
In an energy meter copper shading bands are provided to :
Answer
A. Bring flux exactly in quadrature with applied voltage
87
A multimeter is used for the measurement of which of the following :
(i) ac voltage and current
(ii) dc voltage and current
(iii) energy
(iv) power
Answer
A. Only (i) and (ii)
88
Which of the following method is used for the measurement of Medium Resistance?
Answer
B. Wheatstone's bridge
89
The bridge that is used to measure the inductance of a coil is :
Answer
D. Maxwell’s Bridge
90
Arrange the following components in a data acquisition system :
(1) Amplifier
(2) Analog to Digital converter
(3) Filter
(4) Sensors and Transducers
(5) Display
Answer
B. (4)-(3)-(1)-(2)-(5)
91
How much on-chip RAM is available in 8051 microcontroller?
Answer
B. 128 bytes
92
Which special function register of 8051 microcontroller is used to hold the memory
address during a data transfer from external memory?
Answer
D. DPTR
93
The initial value in the SP register of 8051 microcontroller after a system reset :
Answer
C. 07H
94
Which port pins of 8051 microcontroller have no alternate functions?
Answer
B. Port 1
95
Which bit in the PSW register of 8051 microcontroller functions as the AC flag?
Answer
C. PSW.6
96
Which range of addresses in the 8051 microcontroller’s internal RAM is dedicated to
bit-addressable memory?
Answer
D. 20H to 2FH
97
Which control signal of 8051 microcontroller is used to read a program code byte from an
external EPROM memory?
Answer
D. PSEN
98
Which of the following instructions written for 8051 microcontroller uses direct
addressing mode for data transfer?
Answer
A. MOV A, 30h
99
Which part of the following special function register of 8051 microcontroller has control
bits and flags for the external interrupts?
Answer
C. Lower nibble of TCON
100
If the crystal frequency of 8051 microcontroller is 12 MHz, what will be the timer clock
frequency?
Answer
A. 1MHz
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