| Post Name | ELECTRICAL SUPERVISOR-APPEX SOCIETIES |
|---|---|
| Question Paper Code | 001/2022 |
| Category Code | 223/2020 |
| Date of Test | 1 January 2022 |
| Medium of Question | ENGLISH |
| Exam Type | OMR Examination |
| Total Questions | 100 |
1
The reciprocal of resistance is
Answer
B. Conductance
2
Two waves of the same frequency have opposite phase when the phase angle between them is
Answer
A. 180°
3
The best place to install a capacitor is
Answer
B. Across the terminals of the inductive load
4
The time constant of a series R-C circuit is given by
Answer
C. RC
5
The material which has a negative temperature coefficient of resistance is
Answer
D. Carbon
6
A dependent source
Answer
A. May be a current source or voltage source
7
Capacity of a dry cell is
Answer
C. More when it supplies current intermittently
8
In a lead acid cell, on discharging, both the plates change and become
Answer
D. Lead sulphate
9
High current of the order of 100 A can be measured by an ammeter of 0-1 A rating by using
Answer
D. Current transformer
10
Electrical devices and appliances are not connected in series because
Answer
C. Devices have different current rating
11
The force of attraction or repulsion between two magnetic poles is inversely proportional to the square of the distance between them. This is known as
Answer
D. Coulomb's second law
12
Who discovered the relationship between magnetism and electricity that serves as the foundation for the theory of electromagnetism?
Answer
B. Hans Christian Oersted
13
A permanent magnet will not attract
Answer
A. Copper
14
The unit of magnetomotive force is
Answer
C. Ampere turns
15
Which of the following is a vector quantity?
Answer
Question Cancelled
16
The polarity of induced voltage while a field is collapsing is
Answer
B. Opposite to the force creating the field
17
Comparing superparamagnetic and ferromagnetic materials, which statement is false?
Answer
Question Cancelled
18
Lower the self inductance of a coil
Answer
D. Smaller the delay in establishing steady current through it
19
It is difficult to magnetise steel because of its
Answer
C. Low permeability
20
The value of dielectric constant for vacuum is taken as
Answer
A. 1
21
To reduce the error in voltmeter and ammeter due to friction torque
Answer
C. The torque weight ratio must be large
22
The controlling torque T_c of a Moving Iron instrument is
Answer
B. Kθ
23
Correction factor of wattmeter for lagging load is
Answer
A. cos φ/[cos β cos(φ-β)]
24
When 3 phase power is measured by 2 wattmeter method one of the wattmeter will read zero power
Answer
D. If the load power factor is 0.5
25
Light load compensation of integrated type energy meter is done by
Answer
C. Shading loop
26
Single phase electrodynamometer power factor meter consists of
Answer
A. Two identical pressure coils and one current coil which is split up into two parts
27
Ferro dynamic type frequency meter is a
Answer
B. Electrical resonance type frequency meter
28
The bridge circuit which measures self inductance in terms of standard capacitor is
Answer
Question Cancelled
29
In a CRO intensity of electron beam is controlled by
Answer
C. Grid
30
The primary current in the CT is
Answer
B. Independent of the secondary circuit conditions
31
One complete cycle of alternating quantity is said to be spread over
Answer
D. 2π radians
32
Amplitude factor of sinusoidal alternating voltage is
Answer
B. E_m/(E_m/√2)
33
What will be the reading of hot-wire voltmeter if it is connected across the terminal of a generator whose voltage wave form is represented by V = 100 sin ωt + 50 sin 3ωt + 25 sin 2ωt?
Answer
C. 81
34
The instantaneous value of a quantity is 5 Sin (2πft - 1). Then the phase in degree with respect to the quantity of reference is
Answer
A. 57.3°
35
When pure inductive coil is connected to an AC supply then the average demand of power from power supply is
Answer
A. Zero
36
The inductive reactance offered to the third harmonic component of the voltage is
Answer
B. 6πfL
37
The current in a pure capacitor leads its voltage by
Answer
C. Quarter cycle
38
When three phase symmetrical balanced load is connected to 3 phase 4 wire star system, the neutral wire will be carrying three currents which are exactly equal in magnitude but
Answer
D. are 120° out of phase with each other
39
In a 3 phase star connection system φ is the
Answer
A. Angle between phase voltage and phase current
40
For a balanced star connected system, load impedance per phase Z_y is equal to
Answer
A. Z_Δ/3
41
The efficiency of a solar cell is between
Answer
B. 15% to 20%
42
The purpose of earthing the electrical equipment is
Answer
C. Both A) and B)
43
Fillers in a lead acid battery are provided to
Answer
A. Allow flow of gases
44
In which solar energy collector the efficiency is maximum?
Answer
D. Paraboloid dish
45
The primary purpose of a grounding system is to provide a ______ path for currents to the earth.
Answer
B. Low impedance
46
Two 12 Volt 60 Ah batteries are connected in parallel, we get ______ output.
Answer
A. 12 Volt 120 Ah
47
Hydrometer is used to measure the ______ in a lead acid cell.
Answer
B. Specific gravity of electrolyte
48
The capacity of a cell increases with
Answer
D. All of the above
49
For ______ voltages and ______ body resistances will increase the degree of electrical shock to the human body.
Answer
C. higher, lower
50
Which of the following device will not operate at fault?
Answer
A. Isolator
51
Melting point of Tungsten is
Answer
D. 3400°C
52
One lumen/M²
Answer
A. One lux
53
The fuse in DC circuit is inserted in
Answer
C. Both negative and positive lines
54
The unit of solid angle is
Answer
D. Steradian
55
Carbon arc lamps are commonly used in
Answer
C. Cinema projector
56
The HRC fuses are standardized for rated current up to ______ Ampere.
Answer
C. 1250
57
Current rating of 1.5 mm² single core copper wire is ______ Amps.
Answer
B. 10
58
The earth resistance of a domestic wiring is
Answer
A. Less than 5 ohms
59
The action of a fuse is based on the ______ effect of the electric current.
Answer
B. Heating
60
To improving the efficiency of earthing by
Answer
D. All of the above
61
Which of the following statements is/are true regarding the functions of yoke in a dc machine? i. It provides path for the pole flux. ii. It provides mechanical support to the machine. iii. It helps to convert the AC EMF to DC. iv. It helps in reducing the armature reaction effect.
Answer
A. Only i and ii
62
The number of parallel paths in a 4 pole wave wound dc machine is
Answer
B. 2
63
In order to obtain maximum generated EMF in the armature of a dc generator, what should be the shape of field flux waveform?
Answer
A. Flat topped waveform
64
Match the following starters and the motors in which they are employed? I: 1. Three pointer starter; 2. Four point starter; 3. Two point starter. II: i. DC shunt motor with field control; ii. DC shunt motor without field control; iii. DC series motor.
Answer
A. 1-ii, 2-i, 3-iii
65
In case of compound dc machines, the reason/reasons for keeping the series field wound over the shunt field coil is/are
Answer
D. Both (A) and (B)
66
The main reason for improper commutation in case of dc machine is
Answer
A. Inductance of armature winding
67
A long shunt dc compound generator delivers 2.2 kW at 220 V. If armature resistance is 0.1 ohms, series field winding resistance is 0.2 ohms and shunt field resistance is 110 ohms, calculate the value of armature current in amperes.
Answer
C. 12 A
68
Which of the following statements is/are true regarding mechanical characteristic of a dc shunt motor? i. It is the graph between torque and speed of motor. ii. It is the graph between armature current and armature torque. iii. The shape of the characteristic is linear. iv. The shape of the characteristics is hyperbolic.
Answer
Question Cancelled
69
During the no load test on a 200 V, DC shunt motor having armature resistance of 0.1 Ω and field resistance of 200 Ω, the armature current is recorded to be 10 A. The constant loss of the motor is
Answer
B. 1990 W
70
A DC shunt motor is running at 1500 rpm. An additional resistance is introduced in the field circuit of the motor without any change in applied voltage. The speed of the motor is
Answer
B. Will be more than 1500 rpm
71
If the input supply frequency of a transformer is doubled, keeping the input voltage constant which of the following statements are true? i. Core loss gets doubled. ii. Eddy current loss gets doubled. iii. Hysteresis loss reduces.
Answer
B. Only iii
72
The purpose of using laminations in a transformer is to reduce
Answer
A. Eddy current loss
73
The rotor EMF frequency of a 3 phase induction motor is found to be 2 Hz and the input supply frequency to the motor is 50 Hz. Calculate the percentage slip of the motor.
Answer
C. 4%
74
Which of the following techniques can be used for speed control of three phase squirrel cage induction motor? i. Rotor resistance control. ii. V/f control. iii. Pole changing method.
Answer
D. Only ii and iii
75
Which of the following statements is/are true regarding star delta starter of three phase induction motor? i. At the time of starting the windings are connected in star and after attaining the steady state speed the windings are connected in delta. ii. At the time of starting the windings are connected in delta and after attaining the steady state speed the windings are connected in star. iii. It reduces the starting torque to one third of that produced by direct switching in delta. iv. It increases the starting torque to three times of that produced by direct switching in delta.
Answer
A. Only i and iii
76
The number of slip rings in a star connected three phase alternator with the field provided on rotor is
Answer
C. 2
77
The armature reaction effect in a three phase alternator operating in isolated condition depends on which of the following? i. Power factor of the load. ii. Speed of the machine. iii. Load current.
Answer
A. Only i and iii
78
Which of the following statement/statements are true regarding damper winding in a three phase synchronous motor? i. Damper winding helps to start the motor. ii. Current is present in damper winding when the motor is running at synchronous speed. iii. Current is zero in damper winding when the motor is running at synchronous speed.
Answer
D. Only i and iii
79
The direction of rotation of a single phase induction motor can be reversed by
Answer
D. Either B or C
80
Which of the following can be employed for speed control of universal motors? i. Resistance connected in series to armature. ii. Tappings provided on field winding. iii. Using centrifugal device.
Answer
D. i, ii and iii
81
The power delivered to the load is maximum when the SCR firing angle is
Answer
C. Zero
82
A UJT has R_BB = 15 K ohms, RB₂ = 5 K ohms. Its intrinsic stand off ratio is
Answer
A. 0.67
83
The operation of JFET involves
Answer
D. Flow of majority carriers
84
For half wave controlled rectifier, if firing angle is θ₁, then average value of output DC voltage is given by
Answer
C. V_dc = (V_m/2π)(cos θ₁ + 1)
85
A TRIAC is equivalent to two SCRs
Answer
B. In inverse parallel
86
Which is an example of DIAC?
Answer
A. NTE 6408
87
A latched up IGBT can be turned off by
Answer
D. Forced commutation of current
88
A single phase half bridge inverter has input supply voltage of 100 volts. For a load resistance of 5 ohms, the output power is equal to (square wave output)
Answer
B. 500 watts
89
The internal resistance of an ideal voltage source is
Answer
C. Zero
90
______ is used in the rotating type UPS system to supply the mains.
Answer
D. Alternator
91
The decimal number -19 is expressed in 2's complement form as
Answer
B. 11101101
92
A overline(A B̄ + Ā B) is equivalent to
Answer
D. AB
93
In negative logic, logic state 1 corresponds to
Answer
Question Cancelled
94
The most suitable gate for comparing two bits is
Answer
B. XOR
95
A feature that distinguishes the JK flip flop from the SR flip flop is the
Answer
D. Toggle condition
96
In a 4 bits weighted resistor D/A converter, the resistor value corresponding to LSB is 64 K Ohms. The resistor value corresponding to MSB will be
Answer
C. 8 K Ohms
97
The disadvantage of counter type A/D converter as compared to comparator type A/D converter is that
Answer
A. Longer conversion time is required
98
A divide by 54 counter can be realized by
Answer
D. one mod 9 counter followed by one mod 6 counter
99
A stage in a shift register consists of
Answer
C. a flip flop
100
The purpose of using flux in soldering is to
Answer
B. Prevent oxides forming
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