UKPSC JE 2013: Uttarakhand Combined Junior Engineer Selection Examination, JE ELECTRICAL ENGINEERING (PAPER-I)
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• ELECTRICAL ENGINEERING
PAPER-I
1. In a single stage amplifier D.0 and A.0 load lines
•(a) are always parallel (b) are perpendicular to each other
(c) cross each other at Q-point (d) are inclined but do not cross each other
2. Phase reversed of 180° as compared to input occurs. in.the output of
(a) -CE amplifier (b) CB amplifier (c) C amplifier (d) All of these
3. Improper biasing of a transistor circuit leads to
(a) excessive heat production in collector.(b) faulty location of load line.
(c) heavy loading of emitter. (d) distortion in output signal.
4. When a P-N junction is reverse biased
(a) it offers high resistance (b) its depletion layer becomes narrow
(c) its barrier potential decreases (d) it breaks down
5. The current gain of a common emitter transistor is 50. The change in emitter current for a
corresponding change of 5 mA in base current will be
(a) 50 mA (b) 55 mA (c) 250 mA (d) 255 mA
6. If the maximum current of a half-wave rectified wave is 10 A, its r.m.s value is given by
(a) 3.1OA (b) 5.OA (c) 6.37A (d) 7.07A
7. A common emitter amplifier is characterized by
(a) low voltage gain (b) very high output impedance
(c) moderate power gain (d) signal phase reversal
8. The maximum rectification efficiency of a half-wave rectifier is
(a) 40.6% (b) 81.2% (c) 88.0% (d) 100%
9. The ripple factor of a power supply is a measure of
(a) its filter efficiency (b) its voltage regulation
(c) its purity of output (d) diode rating
10. The power dissipation in a transistor is the product of
(a) Emitter current and emitter to base voltage.
(b) Collector current and collector to base voltage.
(c)- Emitter current and collector to emitter voltage.
(d) None of the above
11. Consider the following circuit configurations:
1. common emitter
2. common base
3. Emitter follower
The correct sequence in increasing input impedance of these configuration is
(a) 2,1,3 b) 1,2,3 (c) 1,3,2 (d) 3,2,1
12. The forbidden gap of a Germanium semiconductor material is
(a) 0.12 eV (b) 0.72 eV (c) 7.20 eV (d) None of these
13. In the following circuit, forward resistance of diode is zero. For the voltages shown at
input and output of the transformer, the d.c. volta!e across 5 ohm resistor will be
V 200 sin t
5
(a) (b) (c) —V (d) None of these
7t
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14. P-N junction diode is used for the following application:
(a) Amplifier (b) Detector (c) Radio valve (d) None of these
15. In the following figure, V1 = 8.0 V and V2 = 0 V, Which diode will conduct (assume ideal
diodes)?
10 LQ
(a) D1 only (b) D7 only (c) both (a) and (b) (d) neither (a) nor (b)
16. Which one of the following is a non-maskable interrupt?
(a) RST 7.5 (b) RST 6.5 (c) RST 5.5 (d) TRAP
17. A balanced modulator is used for generation of which of the following?
(a) DSB-SC signal (b) FM signal
(c) PM signal (d) PAM signal
18. A FM wave is given as v = 12 sin (6 x 108 t + 5 sin 1250 t). Its carrier frequency is
(a) 60.0 MHz (b) 95.5 MHz (c) 125.0 MHz (d) 276.3 MHz
19. An operational amplifier has a differential gain of 100 and a common mode gain of 0.01.
Its CMRR will be
(a) 20 dB (b) 40 dB (c) 60 dB (d) 80 dB
20. An input of V1 = 5.0 cos Cot is given to an Op-Amp integrator circuit. If R = 2.0 M ohm
and C = 1.0 iiF, then output will be
(a) lOWsinwt (b) 5WsinCot (c) -2.5Wsinwt (d) -0.5Wsinwt
21. The full scale output of an 8 bit DAC for 0 to 10 V range is
(a) 1.961 V (b) 9.961 V (c) 96.11 V (d) 1.996 V
22. Memory range of a memory chip 1 K is
(a) 0000H to O3FFH (b) 000lHto0lFFH
(c) 0000H to O2FFH (d) 0000H to O4FFH
23. Which one of the following gate-symbol combinations is false?
0
(a) NOR gate 0 (b) NAND gate 0 ID 0
(c) AND gate • .
(d) NOT gatc -i>O
24. Which one of the following is equal to A +B !
(a) A•B (b) AB (c) AB (d) AB
25. The basic memory cell in a DRAM is a
(a) MOSFET (b) Capacitor
(c) Capacitor and a MOS switch (d) Flip-Flop
26. Absorption of radio waves in atmosphere depends'on
(a) frequency of waves (b) distance from transmitter
(c) polarisation of waves (d) polarisation of atmosphere
27. Each flip-flop in a 4-bit ripple counter introduces a maximum delay of 40 n sec. The
maximum clock frequency is
(a) 2.65 MHz (b) 6.25 MHz (c) 5.26 MHz (d) 6.52 MHz
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28. Which IC is a decade counter?
(a) 7476 (b) 7486 (c) 7404 (d) 7490
29. Consider following gates:
I. NAND
2. NOR
3. XOR
Out of these gates, the universal gates are
(a) I and 3 only (b) 2 and 3 only (c) I and2on1y (d) l,2and3
30. How many flip-flops are required to build a binary counter circuit to count from 0 to 1023?
(a) I (b) 6 (c) 10 (d) 23
31. The number of NAND gates required to implement a function A + AB + ABC is equal to
(a) 0 (b) I (c) 4 (d) 5
32. With reference to following logic circuit, the output will be
A
(a) A•B (b) AB (c) A+B (d) A+
33. Which of the following are 3 byte instruction set?
(a) MV 1A, 32 H (b) JMP 2085 H (c) MOV C, A (d) ADD B
34. In the following Op-Amp circuit, the output V0 is
20 k~)
(a) 2V1 +V2 -2V3 (b) 2(V1 + V2) V3
-
(c) V1 +V2 +V3 (d) V1 +2V,—V3
35. Which of the following oscillators is used for generation of high frequency signal?
(a) RC phase shift oscillator (b) Blocking oscillator
(c) Wein bridge oscillator (d) L-C oscillator
36. In a positive edge triggered JK flip-flop. J = 1. K = 0 and clock pulse is rising, Q will be
(a) 0 (b) I
(c) showing no change (d) toggle
37. Kaplan turbines are used whenever the water head is
(a) low (b) high (c) medium (d) (b) and (c)
38. The cost of fuel transportation is minimum in
(a) Steam power plant (b) Diesel power plant
(c) Hydro-electric plant (d) Coal based power plant
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28. cil-i T IC c'
• (a) 7476 (b) 748i (c) 7404 (d) 7490
29. 1I(e4:
1. NAND
2. NOR
3. XOR
(a) cj I 3 (b) ci 2 s3t 3 (c) ci I 3*t 2 (d) 1, 2 3 3
30. -3Ti1 O 1023 ui.ii jq,ii
(a) I (b) 6 (c) 10 (d) 23
31. i-i A+AB +ABCi1i ci* i1tt NAND
(a) 0 (b) 1 (c) 4 • (ci) 5
32. Ii-i 111c1
(a) AB (b) AB (c) A+B (d) A+
33. T3!iZ#?
(a) MV 1A, 32 H (b) JMP 2085 H (c) MOV C, A (d) ADD B
34. 1ii Op-Amp 41 I1c1 V0 t:
20 k~
\' I
(a) 2V1 +V2 -2V3 (b) 2(V1 +V,)—V3
(c) V1 + V2 + V3 (d) V1 + 2V7 V3 -
35. Iii 'c c '1Ic1I
(a) RC 'ci' fi-i c11ii (b) i'll'4i c)1vi
(c) ii 'c (d) L-C
36. lc %1-iIcHc, ci1 1i JK-i J = 1, K=0 Q"
(a) 0 (b) 1 (c) '1c'1 R1 (d) ci1Ic.1
37. 'ii- wIt'i ft iir lii
(a) I1H (b) 3t (c) (d) (b)3(c)
38.
(a) T&t ISI ik (b) 'ki t1i .ik. #
(c) f-f 'k'1k (d) .3TT%1TftT i1ii icik.
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39. Economisers are used to heat
(a) Coal (b) Air (c) Steam (d) Feed water
40. In thermal power plants, the pressure of working fluid cy1e is developed by
(a) Condenser (b) Superheater
(c) Feed water pump (d) Turbine
41. A gas turbine power plant is best suited for
(a) base load (b) peak load
(c) emergency purpose (d) None of the above
42. Out of the following plant categories:
(i) Nuclear (ii) Run-off river
(iii) Pump storage (iv) Diesel
The base load power plants are
(a) (i)and(ii) (b) (ii)and(iii) (c) (i), (ii) and (iii) (d) (i), (iii) and (iv)
43. Which of the following components is not a part of hydro-electric plant?
(a) Penstock (b) Spillway (c) Surge tank (d) Economiser
44. Which one is not a commonly used coolant for fast breeder reactor?
(a) Water (b) Liquid metal (c) Helium (d) Carbon dioxide
45. Combined cycle power plants may need
(a) MHD generator (b) Thermionic converter
(c) Thermoelectric generator (d) All of the above
46. The pH value of water used for boiler of thermal power plant is
(a) unity (b) 7
(c) slightly more than 7 (d) 10
47. The expression for power plant output in kilo-watt of a hydro-electric plant is given by
0.736 Q.W.h 0.736 Q.Wh r 75 Q.Wh•
(a) (b) (c) (a) None of these
0.736
48. A cable has inductance of 0.22 mH per kilometer and capacitance of 0.202 iF per
kilometer. The surge impedance of the cable is
(a) 50 (b) 42 (c) 33 (d) 28
49. The first nuclear power plant was built in India at which place?
(a) Tarapur (b) Rana Pratap Sagar
(c) Kalpakkam (d) Narora
50. Sag of conductors between two electric poles can be determined by
WL2 WL2 WL2 WL2
(a) 8T (b) 161 (c) 2T (ci) T
Where W = weight per unit length of conductor in kg/rn
L =. Distance between two poles in metre
I = Tension in conductors in kg-rn
51. The economic size of a conductor in transmission and distribution lines of electric power
is decided by
(a) Ohm's law (b) Kelvin's law (c) KirchhofPs law(d) Faraday's law
52. Which alternator will have more number of poles?
• (a) coupled to steam turbine (b) coupled to gas turbine
(c) coupled to hydraulic turbine (d) None of the above
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53. In an AC transmission line difference in phase of voltage at two ends of the line is due to
(a) System voltage (b) Insulators
(c) Resistance of line (d) Reactance of line
54. If 5000 kW power is transmitted at 220 kV in place of 11 kV, reduction in the value of
electric current will be
(a) 90% (b) 95% (c) 5% (d) 10%
55. In long AC transmission lines, the receiving end voltage becomes greater than sending end
voltage at light load or no load operation. This is due to
(a) Ferranti effect (b) Skin effect
(c) Proximity effect (d) Corona effect
56. For extra high voltage ac transmission lines, conductors used are
(a) All aluminium (b) All steel
(c) AAAC (d) ACSR
57. Which of the following relations is true for long transmission line?
(a) VsAVR — BIR (b) Vs=BVR +AlR
(c) V = AVR + BIR (d) V = BV R — AIR
58. Which of the following is used for power factor improvement in transmission line?
(a) Three phase induction
(b) An overexcited three phase synchronous motor running on no load
(c) Three phase AC series motor
(d) Choke
59. The connected load of a consumer is 2 kW and his maximum demand is 1.5 kW. The load
factor of the consumer is
(a) 0.375 (b) 0.75 (c) 1.33 (d) Noneofthese
60. If diameter of each conductor of a transmission line is 'd', then the diameter of n-layer
stranded conductor will be
(a) (2n— 1)d (b) (2n+ l)d (c) (3n— l)d (d) (3n+ l)d
61. The bundled conductor in EHV transmission line system provides
(a) increased inductance (b) reduced capacitance
(c) increased capacitance (d) increased voltage gradient
62. Corona losses in transmission lines are minimized when
(a) conductor size is reduced. (b) smooth conductor is used.
(c) sharp points are provided in the line. (d) current density in conductor is reduced.
63. The power loss in a transmission line depends on
(a) current in the line. (b) resistance of the line.
(c) length of the line. (d) All of the above
64. The main consideration for operating transmission line at high voltage is
(a) to increase efficiency only.
(b) to reduce power loss only.
(c) to increase power transmission capability only.
(d) All of the above
65. The presence of earth in case of overhead transmission line
(a) increases capacitance (b) increases inductance
(c) decreases capacitance (d) decreases inductance
66. Effect of increase in temperature in an overhead transmission line is
(a) to increase stress and length both (b) to decrease stress and length both
(c) to decrease stress and increase length (d) None of the above
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67.. A 0-10 A ammeter has a guaranteed accuracy of 1% of full scale deflection, the limiting
error while reading 2.5 A will be 4
(a) 1% (b) 2% (c) 4% (d) None of these
68. The constant of a given energymeter is 500 revolution/kWh. At the test 4.4 kW full load,
meter completes 50 revolutions in 86 seconds. The percentage error of the meter is
(a) —4.86% (b) 4.86% (c) 2.0% (d) 3.0%
69. The most efficient form of damping employed in electric instruments is
(a) Air friction damping . (b) Fluid friction damping
(C) Eddy current damping (d) None of the above
70. Which of the following instruments is equally accurate on ac as well as dc circuits
(a) PMMC voltmeter (b) Dynamometer wattmeter
(c) Moving iron ammeter (d) Induction wattmeter
71. The moving system of an indicating type of electrical instrument is subjected to
(a) a detlecting torque (b) a controlling torque
(c) a damping torque (d) All of the above
- 72. Energy meter runs slowly even if power is not used. This error is called
(a) Speed error (b) Phase error (c) Creeping error (d) None of these
73. The type of instruments used mainly for standardizing instruments in laboratories is
(a) Indicating instrument (b) Integrating instrument
(c) Absolute instrument (d) Recording instrument
74. What will happen if a voltmeter is connected like an ammeter in series of the load?
(a) The meter will bum out.
(b) The measurement will be too high.
(c) The same current will flow as would have been with ammeter in circuit.
(d) There will be almost no current in the circuit.
75. Series resistance required to read 0-250 V with a moving coil instrument of internal
resistance 2 ohm and full scale deflection of 50 mA is
(a) 49998 (b) 4998 ~ (c) 498 ~~ (d) 49.8
76. Which of the following is not a method of resistance measurement?
(a) Ammeter — Voltmeter method (b) Post — Office box method
(c) Ohm — Meter method . (d) Two wattmeter method
77. Internal resistance of a micro-ammeter is 500 ohm. Shunt resistance required to increase
its range from 0-100 pA to 0-10 A will be approximately
(a) 0.05 ~ (b) 0.005 Q (c) 0.5 (d) 5.0 ~
78. Hay bridge is suitable for measuring following type of inductance
(a) having Q greater than 10.
(b) having Q less than 10.
(c) having any value of Q.
(d) having phase angle of reactance very large.
79. The dielectric loss of a capacitance can be measured by
(a) Hay bridge (b) Maxwell bridge
(c) Anderson bridge (d) Schering bridge
80. In a particular meter, the deflecting.torque is directly proportional to the current flowing
through it, the type of meter is
(a) moving coil (b) moving iron (c) induction (d) clectro-static
81. For measurement of low resistance, the bridge used is
(a) Wheatstone (b) Kelvin (c) Maxwell (d) Anderson
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82. While measuring power in a three phase load by two wattmeter method, the reading of two
wattmeter are equal and opposite. when
(a) load is balanced (b) power factor is unity
(c) phase angle is between 600 to 90° (d) the load is purely inductive
83. Megger is used to measure
(a) very high resistance or insulation resistance.
(b) low resistance.
(c) high resistance.
(d) very low resistance.
84. If a dynamometer wattmeter is connected in an ac circuit, the power indicated by the
wattmeter will be
(a) volt-ampere product (b) average power
(c) peak power (d) instantaneous power
85. The Maxwell bridge is used for measuring
(a) Capacitance (b) Dielectric loss (c) Inductance (d) Phase angle
86. A compensated wattmeter has its reading corrected for error due to
(a) Frequency (b) Friction
(c) Power consumed in current coil (d) Power consumed in pressure coil
87. A null type of instrument as compared to a deflecting type instrument has
(a) higher accuracy (b) lower sensitivity
(c) faster response (d) All of the above
88. A digital voltmeter has a read-out range from 0 to 9999 counts. When full scale reading is
9.999 V, the resolution of the instrument will be
(a) 100 mV (b) 99 my (c) 9 mV (d) I rnV
89. A VTVM can be used to measure
(a) dc voltage only (b) ac voltage only
(c) both (a) and (b) (d) None of the above
90. The sensitivity of a voltmeter using 0-5 mA meter movement is
(a) 200/V (b) l50/V (c) l00/V (d) 50IV
91. Moving coil instruments have which one of the following scales?
(a) Logarithmic scale (b) Uniform scale
(C) Non-uniform scale (d) Squared scale
92. Super conducting materials can be used for
(a) ore refining.
(b) magnetic levitation in high speed trains.
(c) medical resonance imaging.
(d) Allofthe above
93. Ferrites are types of
(a) magnetic material (b) conducting material
(c) semiconducting material (d) insulating material
94. In which material, valence electrons are tightly bounded to their parent atoms?
(a) Conductor (b) Semiconductor (c) Insulator (d) Magnetic
95. The disc of domestic supply energy meter is made of which material?
(a) Zinc (b) Copper (c) Aluminium (d) Silver
96. The material of hair spring used in measuring instruments is made of which of material of
the tbllowing:
(a) Copper (b) Bronze (c) Alnico (d) None of these
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97. The best suitable material for the heating element is
(a) Tungsten (b) Nichrorne (c) Manganin (d) Carbon
98. Pure silicon is
(a) a p-type semiconductor (b) an n-type semiconductor
(c) an intrinsic semiconductor (d) an extrinsic semiconductor
99. impurity atoms to be added to pure silicon in order to make a p-type semiconductor
belongs to
(a) Phosphorous (b) Boron (c) Antimony (d) Aluminium
100. Resistivity of a wire depends upon
(a) Material (b) Area (c) Length (d) All of these
101. If a ferromagnetic material is heated uptó Curie temperature, it becomes
(a) Permanent magnet (b) Anti-ferromagnetic material
(c) Diamagnetic material (d) Pararnagnetic material
102. At absolute zero temperature, an intrinsic semiconductor behaves as
(a) a good conductor (b) a super conductor
(c) an insulator (d) variable resistor
103. In an intrinsic semiconductor the Fermi level is
(a) closer to valence band.
(b) closer to conduction band.
(c) within the balance band.
(d) midway between the valence and conduction bands.
104. The eIuctance offered by a magnetic material is highest when it is
(a) Diamagnetic (b) Paramagnetic (c) Ferromagnetic (d) None of these
105. If temperature of a pure silicon specimen is increased, then
(a) only number of free electrons increase.
(b) only number of free holes increase.
(c) number of free holes and free electrons increases.
(d) only number of free holes decrease.
106. Varnishes protect the insulating materials against
(a) dust and oil (b) moisture, dirt arid oil
(c) moisture and fire hazards (d) None of the above
107. If a 220V heater is used on 110 V supply, the heat produced by it will be nearly
(a) one half (b) twice (c) one-fourth (d) four times
108. Two sinusoidal currents are given by following equations:
.(It
= 10 sin
It
12 = 1 5 sin
The phase difference between them is
(a) 105° (b) 75° (c) 15° (d) 600
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109. The reactance offered by a capacitor to an alternating current o'f frequency 50 Hz s
10 ohm. If frequency is increased to 100 Hz. the reactance will be
(a) 2.5 ohm (b) 5.0 ohm (c) 20.0 ohm (d) 40.0 ohm
110. The r.m.s. value of a half-wave rectified alternating current is 10 A. Its value for full-wave
rectification will be
20 40
(a) A (b) A (c) A (d) 20A
111. In the following figure, the resistance measured across A and B will be
A 2Ok~
15k1~ R. R 5k~~
5 tF
(a) 5k1 (b) l0k (c) I5kL (d) 20k
112. In the fbllowing figure, the voltage across C1 will be
1,tF 21.tF
C1 C2
300 V
(a) 100V (b) 200V (c) 150V (d) 300V
113. An alternating current given by i = 14.14 sin (ox + has an r.m.s. value of
(a) 1.96A (b) 7.07A (c) 10.OA (d) 14.l4A
114. In the following figure, resistor R7 becomes open circuited, the reading of voltmeter will be
Voltrnctcr
2O 20L
+
200V
(a) zero (b) 50 V (c) 150 V (d) 200 V
115. The capacity of a battery is measured in
(a) Watts (b) Watt-hours (c) Amperes (d) Ampere-hours
116. If both the number of turns and core length of an inductive coil are doubled, then its self
inductance will be
(a) halved (b) doubled (c) quadrupled (d) unaffected
117. Mutual inductance between two magnetically coupled coils depends on
(a) number of turns only
(b) permeability of the core only
(c) cross-sectional area of their common core only
(d) All of the above
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168. For a d.c. series motor, which of the following expression is correct assuming torque (T)
versus armature current ('a) characteristics unsaturated?
(a) Toc (b) Toc I (c) Toc I (d) Toc l
where = air gap flux
169. A d.c. series motor should never be started at
(a) normal load condition. (b) full load condition.
(c) no load condition. (d) slightly overload condition.
170. In a d.c. generator, 8 parallel paths and 16 brushes for collection of current are used. If
voltage drop per brush is I V. then reduction in the induced e.m.f. will be
(a) 2V (b) 4V (c) 8V (d) 16V
171. The input impedance of a common base transistor is
(a) Medium (b) Low (c) High (d) Infinity
172. Transistor can be operated in
(a) active region only (b) cut-off region only
(c) saturation region oniy (d) All of the above
173. InaBJT
a 13+1
(a) (b) a= 13 13 1 (c) 131a
(d) a-
'C IC
where 13 = current gain
= B a = current ratio = E
174. For any inverting amplifier, the input capacitance due to Miller effect
(a) increases (h) decreases
(c) remains constant (d) None of these
175. In an amplifier, if voltage shunt negative feedback is employed, then
(a) the bandwidth decreases (b) the output resistance decreases
(c) the input resistance decreases (d) the gain increases
176. Feedback in an amplifier is used to
(a) control output (b) increase gain
(c) decrease input resistance (d) stabilize gain
177. Out of the following hybrid parameters of a transistor which has unit of resistance?
(a) hf (b) h (c) hr (d) h0
178. A transistor has following currents:
= 4.975 A
Then 'E is equal to
(a) 5.225 A (b) 4.95 A (c) 5.0 A (d) None of these
179. When used as a voltage regulator, a zener diode is normally
(a) forward biased (b) reversed biased
(c) not biased (d) None of the above
180. The expression for voltage gain Av of a positive feedback amplifier is
1
•(a) (b) (c) (d) None of these
1 13 _13A 1 +A
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154. The most common type of prime mover used for low speed alternators is
(a) Steam turbine (b) Petrol engine (c) Hydraulic turbine (d) Diesel eng
155. When speed of an alternator is changed from 3600 rpm to 1800 rpm, the generated ernf
will be
(a) one-half (b) twice (c) one-fourth (d) four times
156. The power factor of an alternator is determined by its
(a) prime mover (b) speed (c) excitation (d) load
157. The efficiency of an ordinary transformer is maximum when
(a) it runs at half of full speed (b) it runs at full load
(c) copper losses are equal to iron losses (d) it runs at slightly overload
158. At light load, efficiency of a transformer is low. It is because
(a) copper loss is small.
(b) copper loss is high.
(c) secondary output is low.
(d) fixed loss is high with respect to output.
159. The essential condition for parallel operation of two single phase transformers is that they
should have the same
(a) Polarity (b) kVA rating
(c) Voltage ratio (d) Percentage impedance
160. A transformer transforms
(a) frequency only (b) voltage only
(c) current only (d) voltage and current
161; Which of the following connections of a three phase transformer are best suited for
3-phase, 4-wire service?
(a) (b) T-1' (c) i—T (d) T-
162. Transformers are rated in kVA instead of kW, because
(a) load power factor is often not known.
(b) total transformer loss depends on volt-ampere.
(c) kVA is fixed where as kW depends on load power factor.
(d) None of the above
163. A transformer has negative voltage regulation when its load power factor is
(a) Zero (b) Leading (c Unity (d) Lagging
164. A 4-pole dc generator runs at 1500 rpm. The frequency of current in armature winding is
(a) zero (b) 25 Hz (c) 50 Hz (d) 100 Hz
165. The no load current in a transformer lags the supply voltage by
(a) 0 (b) 90° (c) 1100 (d) about 75°
166. Two mechanically coupled alternators deliver power at 50 Hz and 60 Hz respectively. The
highest speed of alternators is
(a) 600 rpm (b) 500 rpm (c) 3000 rpm (d) 3600 rpm
167. The heat run test of a transformer without its loading is performed by means of
(a) Short circuit test
(b) Open circuit test
(c) Halftime short circuit test and halftime open circuit test
(d) Sumpner's test
Series-C 26 KAU-07
Text of page 27
140. A delta connected load with resistance of 6 ohm and inductive reactance of 8 ohm in ch
phase is supplied by a 3-phase, 400 V, 50 Hz, AC supply. The value of total power d n
by the load is
(a) 28.8 kW (b) 14.0kW (c) 10.8 kW (d) 52.0 kW
141. The frequency of voltage generated in a 4-pole alternator rotating at 1800 r.p.m. is
(a) 25 Hz (b) 30 Hz (c) 60 Hz (d) None of these
142. A 50 Hz alternator will run at the highest speed if it is wound for
(a) 8 poles (b) 6 poles (c) 4 poles (d) 2 poles
143. A transformer having 1000 turns in primary winding is connected to a single phase 250 V
a.c. supply. For inducing 400 V in secondary winding, the number of turns in secondary
winding must be
(a) 1600 (b) 1250 (c) 400 (d) 250
144. The field poles and armature core of a d.c. generator are laminated in Order to reduce
(a) Hysteresis loss . (b) Eddy current loss.
(c) Weight (d) Speed
145. Which one of the following methods gives voltage regulation higher than the actual value
in an alternator?
(a) ZPF method (b) mmf method (c) emf method (d) . ASA method
146. If speed of a d.c. shunt motor is increased above the rated speed, then the counter e.m.f.
(a) increases (b) decreases
(c) remains unchanged (d) first increases and then decreases
147. The open current test in a transformer gives
(a) iron losses (b) copper losses (c) friction losses (d) total losses
148. The mechanical power developed in a d.c. motor is equal to
(a) power input — core losses (b) power input — mechanica! losses
(c) Armature current x counter e.m.f. (d) Armature current x supply voltage
149. An electric train employing a d.c. series motor is running at a fixed speed. When a sudden
drop in voltage of supply takes place, then this results in
(a) drop in speed and rise in current. (b) rise in speed and drop in current.
(c) . rise in speed and rise in current. (d) drop in speed with current unaltered.
150. A 220 V dc shunt motor is running at 500 rpm when armature current is 50 A. The value
of armature resistance is 0.2 ohm. The speed of motor at the double torque will be
(a) 250 rpm (b) 500 rpm (c) 1000 rpm (d) 476 rpm
151. A 10 kVA 220 V/220 V, 50 Hz transformer shows 340 W in short circuit test and 168 W
in open circuit test. Its efficiency at full load and 0.8 power factor lagging is approximately
(a) 92% (b) 94% (c) 96% (d) 98%
152. If number of poles in lap wound d.c. generator are doubled, the generated e.m.f. will be
(a) increased by a factor of 2 (b) decreased by a factor of 2
(c) increased by a factor of 4 (d) unchanged
153. A d.c. series motor has linear magnetization characteristics and negligible armature
resistance. The motor speed is
(a) directly proportional to -..ft (b) inversely proportional to
(c) directly proportional to T (d) inversely proportional to T
where T = load torque
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Text of page 29
129. An R-L series AC circuit has R 10 ohm and X L = 10 ohm. It is connected to an P4
voltage source, the phase angle between voltage and current is
(a) 30° (b) 450 (c) 60° (d) 36.8°
130. The current I flowing in the following circuit is
30 I
(a) zero (b) IA (c) —1A (d)
131. The capacitance of a capacitor is not affected by
(a) Plate area (b) Plate separation
(c) Nature of dielectric (d) Plate thickness
132. A 220 V, 200 W bulb and a 220 V. 100 W bulb are connected in series across a 220 V
supply, the power consumed by them will be
(a) 33.3 W (b) 66.6 W (c) 100 W (d) 300 W
133. The direction of inducted e.m.f. can be found with the help of
(a) Fleming's right hand rule (b) Kirchhoffls voltage law
(c) Lenz's law (d) Laplace's law
134. If I ampere current is flowing through a 100 mH coil, then energy stored in the coil is
(a) 0.05 Joules (b) 0.5 Joules (c) 5.0 Joules (d) None of these
135. In the following figure, the equivalent resistance at terminals A and B will be
100
A
50Q
B
(a) 275 (b) l80 (c) 118.75 (d) None of these
136. The maximum power dissipation in a resistance from a battery of electromotive force E'
and internal resistance 'r' will be
E2 E' E2
(a) (b) ;;;; (c) (d) r
137. Two heater wires of equal length are connected first in series and then in parallel. The
ratio of heat generated from series to parallel connection will be
(a) 4: 1 (b) 2 : I (c) 1:2 (d) 1:4
138. When the current in a coil is increased from 2 A to 4 A in 0.05 seconds, the e.m.f.- induced
in the coil is 8 V. The self inductance of the coil is
(a) 0.8 H (b) 0.4 H (c) 0.2 H (d) 0.1 H
139. The induced e.m.f. will be maximum when a conductor cuts the magnetic field at an angle of
(a) 15° (b) 30° (c) 450 (d) 90°
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Text of page 31
118. For sinusoidal waveform, the ratio of average value to r.m.s. value is
j3 2
2 (c) (d)
(a) 2-T2 IC
119. For an.RLC series AC circuit, the current at.series resistance is
(a) maximum atlagging power factor (b) maximum at leading power factor
(c) maximum at unity power factor.. (d) minimum at unity power factor
120. If v = (a + jb) and i (c + jd), thçn active power is given by
(a) ac+ ad (b) •ac + bd (c) bc bd (d) ad + bc
121. The voltage phasor of a circuit is 10 L15° V and current phasor is 2 L-45° A. The
reactive power in the circuit will be
(a) 17.32 VAR (b) lO\T 2 VAR (c) 8.66 V AR (d) None of these
122. If a capacitance is charged by a square wave current source, then the voltage across the
capacitor will be
(a) . Square wave b) Step function
(c) Triangular wave (d) Zero
123. In the circuit shown below, the terminals A and B are short circuited, the current drawn
from the battery is
R
V 2V V
(a) (b) -j- (c) (d) zero
124. In the following circuit, the equivalent capacitance between terminals A and B is
C
(a)T (b) (c) C (d) 3C
125. The output voltage of a battery drops from 100 V with zero load current to 80 V when load
current is 2 A. The internal resistance of the battery is
(a) 10 L (b) 20 1 (c) 40 (d) 50
126. A charge of 0.1 coulomb moves through a given point in every 0.05 seconds. The current
flowing through the point is
(a) 2 mA (b) 5 mA (c) 2 A (d) 5 A
127. Which of the following capacitors are used in D.C. circuits?
(a) Mica (b) Air (c) Ceramic (d) Electrolytic
128. In an RLC series AC circuit, if frequency is below the resonant frequency, then
(a) X = XL (b) X <XL (c) X. > XL (d) None of these
Series-C 20 KAtJ-07
Official key not published for this paper.
Page 1 of 32
Source: Uttarakhand Public Service Commission. Question paper published by Uttarakhand Public Service Commission.