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Electrical Engineering(Volume - I)

(Engineering Mathematics, Electrical Materials, Electric Circuits & Fields, Electrical and Electronic Measurements, Computer Fundamentals, Basic Electronics Engineering)

Previous years Objective Questions with Solutions, Subjectwise & Chapterwise (1992 - 2018)

ACEEngineering Publications

(A Sister Concern of ACE Engineering Academy, Hyderabad)

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ESE - 19(P )

Copyright © ACE Engineering Publications 2018

All rights reserved.

Published at :

Authors : Subject experts of ACE Engineering Academy, Hyderabad

While every effort has been made to avoid any mistake or omission, the publishers do not owe any responsibility for any damage or loss to any person on account of error or omission in this publication. The publishers will be obliged if mistakes are brought to their notice through email, for correction in further editions.Email : [email protected]

First Edition : 2011Revised Edition : 2018

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Price : ₹. 800/- ISBN : 978-1-946581-38-9

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ForewordUPSC Engineering Services in Electrical Engineering

Volume - I Objective Questions: From 1992– 2018

The Stage-I (Prelims) of ESE – 2018 consists of two objective papers. Paper-I is of General

Studies & Engineering Aptitude. Paper-II is of Electrical Engineering of 300 Marks and 3 hours

duration. In stage-II (Mains), the technical syllabus is divided into two papers. The subjects

included in this volume are:

1. Engineering Mathematics 2. Electrical Materials

3. Electric Circuits & Fields 4. Electrical & Electronic Measurements

5. Computer Fundamentals 6. Basic Electronics Engineering

Keeping in view of the above topics, the present Volume-I for prelims of new pattern is redesigned using the

previous questions from 1992 onwards.

The style, quality and content of the Solutions for previous ESE Questions of Electrical Engineering, will encourage

the reader, especially the student whether above average, average or below average to learn the concept and

answer the question in the subject without any tension. However it is the reader who should confi rm this and any

comments and suggestions would be pleasantly received by the Academy.

It is observed that majority of ESE objective Questions are being asked as it is in many PSUs, state service

commission, state electricity boards and even in GATE exam. Hence we strongly recommend all students who are

competing for various competitive exams to use this book according to the syllabus of the exam concerned. This

book can also be used by fresh Teachers in engineering colleges to improve their Concepts.

We proudly say that questions and solutions right from 1992 onwards are given in this book. The questions which

appeared early 90’s are most conceptual oriented and these are being repeated in the recent exams in a different

way. Hence we advise the students to practice these questions compulsorily. The student is also advised to analyze

why only a particular option is correct and why not others. Evaluate yourself, in which case, these other options

are correct. With this approach you yourself can develop four questions out of one question.

The student is advised to solve the problems without referring to the solutions. The student has to analyze the given

question carefully, identify the concept on which the question is framed, recall the relevant equations, fi nd out the

desired answer, verify the answer with the fi nal key such as (a), (b), (c), (d), then go through the hints to clarify his

answer. The student is advised to have a standard text book ready for reference to strengthen the related concepts,

if necessary. The student is advised not to write the solution steps in the space around the question. By doing so,

he loses an opportunity of effective revision.

With best wishes to all those who wish to go through the following pages.

Y.V. Gopala Krishna Murthy,M Tech. MIE,

Chairman & Managing Director,ACE Engineering Academy,

ACE Engineering Publications.

1. Engineering Mathematics: Matrix theory, Eigen values & Eigen vectors, system of linear equations, Numerical methods for solution of non-linear algebraic equations and diff erential equations, integral calculus, partial derivatives, maxima and minima, Line, Surface and Volume Integrals. Fourier series, linear, nonlinear and partial diff erential equations, initial and boundary value problems, complex variables, Taylor’s and Laurent’s series, residue theorem, probability and statistics fundamentals, Sampling theorem, random variables, Normal and Poisson distributions, correlation and regression analysis.

2. Electrical Materials: Electrical Engineering Materials, crystal structures and defects, ceramic materials, insulating materials, magnetic materials – basics, properties and applications; ferrities, ferro-magnetic materials and components; basics of solid state physics, conductors; Photo-conductivity; Basics of Nano materials and Superconductors.

3. Electric Circuits and Fields: Circuit elements, network graph, KCL, KVL, Node and Mesh analysis, ideal current and voltage sources, Thevenin’s, Norton’s, Superposition and Maximum Power Transfer theorems, transient response of DC and AC networks, Sinusoidal steady state analysis, basic fi lter concepts, two-port networks, three phase circuits, Magnetically coupled circuits, Gauss Theorem, electric fi eld and potential due to point, line, plane and spherical charge distributions, Ampere’s and Biot-Savart’s laws; inductance, dielectrics, capacitance; Maxwell’s equations.

4. Electrical and Electronic Measurements: Principles of measurement, accuracy, precision and standards; Bridges and potentiometers; moving coil, moving iron, dynamometer and induction type instruments, measurement of voltage, current, power, energy and power factor, instrument transformers, digital voltmeters and multi-meters, phase, time and frequency measurement, Q-meters, oscilloscopes, potentiometric recorders, error analysis, Basics of sensors, Transducers, basics of data acquisition systems.

5. Computer Fundamentals: Number systems, Boolean algebra, arithmetic functions, Basic Architecture, Central Processing Unit, I/O and Memory Organization; peripheral devices, data representation and programming, basics of Operating system and networking, virtual memory, fi le systems; Elements of programming languages, typical examples.

6. Basic Electronics Engineering: Basics of Semiconductor diodes and transistors and characteristics, Junction and fi eld eff ect transistors (BJT, FET and MOSFETS), diff erent types of transistor amplifi ers, equivalent circuits and frequency response; oscillators and other circuits, feedback amplifi ers.

Syllabus for Electrical Engineering (EE)

I. Engineering Mathematics

01. Linear Algebra ........................................................................................... 02 - 05

02. Numerical Methods .................................................................................... 06 - 08

03. Calculus ...................................................................................................... 09 - 11

04. Fourier Series ............................................................................................. 12 - 19

05. Diff erential Equations ................................................................................ 20 - 25

06. Complex Variables ..................................................................................... 26 - 30

07. Probability .................................................................................................. 31 - 38

II. Electrical Materials

01. Crystallography .......................................................................................... 40 - 48

02. Conducting Materials ................................................................................. 49 - 62

03. Magnetic Materials .................................................................................... 63 - 100

04. Superconductors ......................................................................................... 101 - 112

05. Dielectric Materials .................................................................................... 113 - 136

06. Semiconductors .......................................................................................... 137 - 159

07. Lasers, Capacitors and Resistors ................................................................ 160 - 164

III. Electric Circuits & Fields

01. Network Elements ..................................................................................... 166 - 227

02. Network Theorems ..................................................................................... 228 - 251

03. Transient Response .................................................................................... 252 - 294

04. Sinusoidal Steady state Analysis ................................................................ 295 - 341

05. Two-Port Networks .................................................................................... 342 - 374

06. Three Phase Circuits ................................................................................... 375 - 380

07. Network Synthesis ..................................................................................... 381 - 407

CONTENTSSNNOCONTENTS

08. Basics of Electromagnetics ....................................................................... 408 - 480

09. Maxwell’s Equations .................................................................................. 481 - 514

10. Electro Magnetic Waves ............................................................................ 515 - 531

11. Transmission Lines ................................................................................... 532 - 556

IV. Electrical and Electronic Measurements

01. Error Analysis & Units and Dimensions..................................................... 558 - 574

02. Basic Instruments ....................................................................................... 575 - 590

03. Potentio meter ............................................................................................ 591 - 594

04. Bridge Measurement of R, L & C .............................................................. 595 - 618

05. Measurement of Power .............................................................................. 619 - 634

06. Measurement of Energy ............................................................................ 635 - 642

07. Instrumentation Transformers..................................................................... 643 - 644

08. Introduction of elctronic instruments.......................................................... 645 - 655

09. Electronic Voltmeters ................................................................................. 656 - 665

10. Digital voltmeters ....................................................................................... 666 - 674

11. Q- Meters .................................................................................................... 675 - 677

12. Cathode Ray Oscilloscope ......................................................................... 678 - 687

13. DF Meter and Analyzers ............................................................................ 688 - 690

14. Transducers ................................................................................................ 691 - 724

V. Computer Fundamentals

01. Number Systems & Boolean Algebra ....................................................... 726 - 738

02. CPU Organization ..................................................................................... 739 - 741

03. I/O Organization ....................................................................................... 742 - 749

04. Memory Organization and Secondary Memory ....................................... 750 - 760

05. Basics of Operating System ....................................................................... 761 - 763

06. Memory Management (Virtual Memory) ................................................... 764 - 766

07. File Systems ............................................................................................... 767 - 768

08. Programming (C Language) ....................................................................... 769 - 772

09. Basics of Networking ................................................................................. 773 - 774

VI Basic Electronics Engineering

01. Basics of Diodes ....................................................................................... 776 - 801

02. BJT Characteristics .................................................................................... 802 - 818

03. JFET Characteristics ................................................................................. 819 - 828

04. MOSFET Characteristics ........................................................................... 829 - 837

05. Biasing Circuits .......................................................................................... 838 - 846

06. Amplifi er Circuits........................................................................................ 847 - 853

07. Frequency Response .................................................................................. 854 - 859

08 .Oscillators ................................................................................................. 860 - 864

09. Feedback Amplifi ers ................................................................................. 865 - 871

10. Power Amplifi ers ...................................................................................... 872 - 876

11. Waveform Generations .............................................................................. 877 - 879

Electrical EngineeringPrevious years ESE Objective questions (Prelims)

Weightage (2014 to 2018)

S.No. Name of the Subject 2014 2015 2016 2017 2018

01 Engineering Mathematics – – – 14 10

02 Electrical Materials 18 20 19 26 09

03 Electric Circuits & Fields 38 45 46 31 30

04 Electrical & Electronic Mea-surements 37 27 30 12 06

05 Computer Fundamentals – – – 03 12

06 Basic Electronics Engineering – – – 04 03

07 Analog & Digital Electronics 63 53 53 06 07

08 Systems & Signal Processing – – – 07 03

09 Control Systems 27 28 26 14 21

10 Electrical Machines 27 34 34 11 26

11 Power Systems 12 12 20 12 19

12 Power Electronics & Drives 18 21 13 10 04

Total No.of Questions: 150 150

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0

10A

1 2 3 t

1A 1

1

R = 2

A

A

Fig.

1A 1

5

5V V1

+

Fig.

I1

+

–

I

10A 4

28

8

Fig.

5A

01. The number of turns of a coil having a time

constant T are doubled. Then the new time constant will be (IES-92)

(a) T (b) 2T (c) 4T (d) T / 2 02. In the circuit shown, the V1 and I1 will be (IES-92)

(a) 1 V, 1 A (b) 1 V, 6 A (c) 5V, 5A (d) None of the above. 03. Current having wave form shown is flowing

in a resistance of 10 ohms. The average power is (IES-92)

(a) W1

1000 (b) W2

1000

(c) W3

1000 (d) W4

1000

04. A 24 V battery of internal resistance r = 4 ohm is connected to a variable resistance R. The rate of heat dissipated in the resistor is maximum when the current drawn from the battery is I. The current drawn from the battery will be (I/2) when R is equal to

(IES-92) (a) 8 ohm (b) 12 ohm (c) 16 ohm (d) 20 ohm 05. In the figure shown, if we connect a source

of 2 V, with internal resistance of 1 at AA, with positive terminal at A, then the current through R is (IES-92)

(a) 2 A (b) 1.66 A (c) 1. A (d) 0.625 A 06. In the circuit shown the value of I is

(IES-92)

(a) 1 A (b) 2 A (c) 4 A (d) 8 A

Chapter

1 NetworkElements

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0.1F

0.1F

0.1F 0.1F

0.1F

a b c d

Fig.

1k

1k 1k

2 V

R=1k

1V

+

+1A

Fig.

+

3V 6A 1 3

4 2

07. When all the resistances in the circuit are of one ohm each, the equivalent resistance across the points A and B will be (IES-92)

(a) 1 (b) 0.5 (c) 2 (d) 1.5 08. A battery is connected to a resistance

causing a current of 0.5 A in the circuit. The current drops to 0.4 A when additional resistance of 5 is connected in series. The current will drop to 0.2 A when the resistance is (IES-92)

(a) 10 (b) 15 (c) 25 (d) 30 09. The current in resistor R shown in figure

will be (IES-92) (a) 0.2 A (b) 0.4 A (c) 0.6 A (d) 0.8 A 10. The equivalent capacitance across ab will be:

(IES-92)

(a) 0.2 F (b) 0.1 F (c) 0.5 F (d) 0 11. Assertion (A): Kirchhoff’s current law is

valid for an ac circuit containing R, L and C. Reason (R): The sum of rms currents at

any junction of the circuit is always zero. (IES-93)

Codes: (a) Both A and R are true and R is the

correct explanation of A (b) Both A and R are true but R is NOT a

correct explanation of A (c) A is true but R is false (d) A is false but R is true

12. In the circuit shown in the figure, the

voltage across the 2 ohm resistor is (IES-93)

(a) 6 V (b) 4 V (c) 2 V (d) zero 13. If a capacitor is energized by a symmetrical

square wave current source, then the steady –state voltage across the capacitor will be a

(IES-93) (a) square wave (b) triangular wave (c) step function (d) impulse function

C

B A

D

196

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ElectricCircuits&Fields ACE Engineering Publications

Solutions

Which of the above statements are correct? (ESE-18) (a) 1 and 2 only (b) 1 and 3 only (c) 2 and 3 only (d) None of the above

188. A pulse of+10V in magnitude and 2s in

duration is applied to the terminals of a lossless inductor of 1.0H. the current through the inductor would (ESE-18) (a) be a pulse of +20A for the duration of

2s (b) be a pulse of –20A for the duration of 2s (c) increase linearly form zero to 20A in 2s,

and in the positive direction, and, from thereon, it remains constant at +20A

(d) increase linearly form zero to–20A in 2s, and in the negative direction, and, from thereon, it remains constant at –20A

KEY 01. b 02. c 03. c 04. b 05. d 06. b 07. b 08. d 09. a 10. b 11. c 12. c 13. b 14. a 15. a 16. b 17. c 18. d 19. a 20. c 21. d 22. c 23. a 24. d 25. d 26. d 27. c 28. b 29. c 30. c 31. d 32. a 33. c 34. b 35. c 36. a 37. c 38. c 39. a 40. a 41. b 42. b 43. b 44. b 45. a 46. c 47. c 48. b 49. b 50. a 51. d 52. a 53. d 54. c 55. a 56. d 57. a 58. b 59. a 60. b 61. d 62. c 63. c 64.c 65. b 66. a 67. d 68. c 69. c 70. a 71. b 72. d 73. c 74. d 75. a 76. c 77. c 78. c 79. b 80. c

81. b 82. a 83. c 84. a 85. a 86. a 87. c 88. a 89. b 90. d 91. b 92. d 93. a 94. c 95. b 96. d 97. a 98. b 99. d 100. b 101. a 102. d 103. b 104. c 105. b 106. d 107. a 108. b 109. a 110. d 111. b 112. b 113. b 114. d 115. d 116. c 117. a 118. a 119. b 120. c 121. c 122. b 123. c 124. a 125. d 126. b 127. c 128.d 129. a 130. c 131. a 132.c 133. b 134. b 135. b 136. c 137. c 138. c 139. c 140. c 141. b 142.d 143. b 144. d 145. a 146. a 147. c 148. a 149. b 150. a 151. c 152. * 153. d 154. b 155. a 156. b 157. d 158. d 159. b 160. c 161. c 162. d 163. b 164. d 165. * 166. a 167. b 168. b 169. c 170. b 171. d 172. c 173. a 174.d 175. d 176. b 177. d 178. b 179, b 180. a 181, a 182. c 183. d 184. b 185. c 186. b 187. d 188. c

01. Ans: (b) Sol: L N2, R N If N is doubled,

21,

41

2

1

2

1 R

R

L

L

21

21

22

11

2

1

//

//

RR

LL

RL

RL

T

T

New Time constant, T2 = 2 T1 = 2 T 02. Ans: (c) Sol: v(t) across 1 = 5 V i(t) across 1 = 5 A Note that 1 A source has no effect.

197


NetworkElementsACE Engineering Publications

03. Ans: (c) Sol: T = 1 sec, i(t) = 10 t, 0 < t < 1, R = 10 p(t) = i2(t) R = 1000 t2

Average Power =

T

t

tdtpT

P0

)(1

3

10003

100010001

0

31

0

2 t

tdt W

04. Ans: (b) Sol: For maximum rate of heat dissipation in R, R = r = 4

248

I = 3A

244 2

I

R

= 1.5,

1.5R + 6 = 24

R = 181.5

= 12

05. Ans: (d) Sol:

The circuit in Fig. 2 is obtained after

simplifying the circuit in Fig.1.

RRR I

II

122

221

2.5 – 3 IR = IR

4 IR = 2.5,

IR = 0.625 A 06. Ans: (b) Sol: 4(10 – I) = 28 I + 8(I – 5)

80 = 40 I, I = 2 A 07. Ans: (b) Sol:

Fig.

24 V R

r = 4

+

3

3 3

1 1

1 A B

D Fig. 1

43

A B

D

43

43

Fig. 2

1

Fig.1

1A 1 R 2 2V+

A

A

1

2

Fig. 2

1V R 2 2V +

1

+

IR

198

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ElectricCircuits&Fields ACE Engineering Publications

The circuit between A, B is simplified as shown in Fig. 1 (star is converted to delta and terminal C is eliminated), and Fig. 2(Terminal D can be eliminated).

5.0

94x

89

23||

43R AB

08. Ans: (d) Sol:

ss VRor

R

VI 25.01

4.052

4.052

s

ss

V

Vor

R

VI

Vs = 0.8 Vs + 2

VVs 102.0

2

R = 20

3 0.2s

x

VI

R R

10 0.2 3020 x

x

RR

09. Ans: (a) Sol: Applying Norton’s theorem to the left and

right of terminals : A, B The circuit is simplified as shown in Fig. 1,

2 and 3.

3

1004 1321 103

RI A

10. Ans: (b) Sol: The equivalent capacitance across a, b is

calculated by simplifying the bridge circuit as shown in Fig. 1 to Fig. 5.

Fig.

Vs R +

I

0.002 A

1k 0.5A 2 k 1 k

1 V

R

Fig. 1

A

B

1 k

1 V

R 2 k3

0.502A

Fig. 2

A

B

1k

1V

IR

Fig. 3

+

(2/3) k

V3

1004R

A

B

AA

BB

DD CC

AA

BB Fig. 1


01. If one of the control springs of a Permanent

Magnet Moving Coil ammeter is broken then, when connected it will read

(IES-92/13) (a) zero (b) half of the correct value (c) twice the correct value (d) an infinite value. 02. Swamping resistance is a resistance which is

added to the moving coil of a meter to (IES-98)

(a) reduce the full-scale current (b) reduce the temperature error (c) increase the sensitivity (d) increase the field strength

03. An indicating instrument is more sensitive if

its torque to weight ratio is (IES-98) (a) much larger than unity (b) of the order of unity (c) much less than unity (d) made deflection-dependent

04. In a flux meter, the controlling torque is (IES-98)

(a) produced by weights attached to the moving coil

(b) produced by spring (c) not provided at all (d) provided by crossed coil mechanism

05. In a PMMC instrument, the central spring stiffness and the strength of the magnet decrease by 0.04% and 0.02% respectively due to a rise in temperature by 10C. With a rise in temperature of 100C, the instrument reading will (IES-99) (a) increase by 0.2% (b) decrease by 0.2% (c) increase by 0.6% (d) decrease by 0.6%

06. In a permanent magnet moving coil instrument, if the control spring is replaced by another one having a higher spring constant, then the natural frequency and damping ratio will (IES-00) (a) decrease (b) increase and decrease respectively (c) decrease and increase respectively (d) increase

07. What is the correct sequence of the

following types of ammeters and voltmeters with increasing accuracy? 1. Moving iron 2. Moving-coil permanent magnet 3. Induction Select the correct answer using the codes given below: (IES-02)

Codes: (a) 1, 3, 2 (b) 1, 2, 3 (c) 3, 1, 2 (d) 2, 1, 3

Chapter

2 BasicInstruments

576 ElectricalMeasurements ACE Engineering Publications


08. The reflecting mirror mounted on the moving coil of a vibration galvanometer is replaced by a bigger size mirror. This will result in (IES-02) (a) lower frequency of resonance and lower

amplitude of vibration (b) low frequency of resonance but the

amplitude of vibration is unchanged (c) higher frequency of resonance and lower

amplitude of vibration (d) higher frequency of resonance but the

amplitude of vibration is unchanged 09. Consider the following statements

associated with moving iron instruments: 1. These can be used in d.c as well a.c

circuits 2. The scale is non-uniform 3. The moving iron is placed in a field of a

permanent magnet. Which of these statements are correct?

(IES-02) (a) 1, 2 and 3 (b) 1 and 2 (c) 2 and 3 (d) 1 and 3 10. A spring controlled moving iron voltmeter

draws a current of 1mA for full scale value of 100V. If it draws a current of 0.5mA, the meter reading is (IES-02)

(a) 25V (b) 50V (c) 100V (d) 200V 11. Torque/Weight ratio of an instrument

indicate (IES-03) (a) Selectivity (b) Accuracy (c) Fidelity (d) Sensitivity

12. Which one of the following materials is used in the fabrication of swamping resistance of a PMMC instruments? (IES-04)

(a) Copper (b)Aluminium (c) Manganin (d) Tungsten 13. Which one of the following is basically a

current sensitive instrument? (IES-04) (a) Permanent magnet moving coil

instrument (b) Cathode ray oscilloscope (c) Electrostatic instrument (d) FET input electronic voltmeter

14. Which one of the following types of

instruments can be used to determine the r.m.s value of ac voltage of high magnitude (10kV) and of any wave shape? (IES-04) (a) Moving iron instruments (b) Dynamometer type instruments (c) Induction instruments (d) Electrostatic instruments

15. Which one of the following statements is

correct? Spiral springs are used in instruments to (IES-04)

(a) provide controlling torque (b) provide damping torque (c) lead the current to moving coil as well as

to provide the controlling torque (d) provide linear deflection

16. Which one of the following decides the time of response of an indicating instrument? (IES-04)

584 ElectricalMeasurements ACE Engineering Publications


Solutions 01. Ans: (a) Sol: In PMMC meter, current passes through

control springs to the moving coil. These control springs are two in number so if one of them is broken then the current path to the moving coil is disrupted.

No deflecting Torque. Since the other control spring is in good

condition, it will hold the pointer at zero indication.

Here control torque has become half of its original value.

02. Ans: (b) Sol: The temperature error can be reduced by

using swamping resistance. This resistance is an alloy of manganin and copper in the ratio of 20:1.

03. Ans: (a) Sol: When torque to weight ratio is high, the

frictional error in instrument will be less and meter has more sensitivity.

04. Ans: (c) Sol: The current is led into the coil with the help

of a very loose helices of very thin, annealed silver strips. The controlling torque is thus reduced to minimum. But no external mechanism to produce controlling torque.

05. Ans: (a) Sol: If stiffness decreases, then the control torque

also decreases and the meter shows more reading. If strength of the magnet is decreased, then the deflection torque will also decrease, but the meter shows less reading.

For 10oC rise in temperature, decreased stiffness = 0.4% and decreased magnet strength is 0.2%.

Hence the percentage decrease of stiffness is more. Therefore the meter show

0.4% 0.2% = 0.2% more reading. 06. Ans: (b) Sol: Equation of motion in PMMC instrument is

GiKdt

dD

dt

dJ

2

2

Where, 2

2

dt

dJ

= Deflecting Torque

dt

dD

= Damping Torque

K = Control Torque J = Moment of Inertia D = Damping Constant K = Spring Constant G = B.N.A Constant

KDsJs

G

)s(I

)s(2

=

J

Ks

J

Ds

J/G

2

KJ

Knn

585 BasicInstrumentsACE Engineering Publications


KJK

D 112

With higher spring constant K, natural frequency increases and damping ratio decreases.

07. Ans: (c) Sol: PMMC has high accuracy and induction

meter has low accuracy. 08. Ans: (b) Sol: The amplitude of vibration at resonance is

not changed, Natural frequency of moving system depends on size of mirror. Therefore with less tuning of moving system the resonance will occur.

09. Ans: (b) Sol: v I2 scale is non-uniform In case of A.C measurement the meter will

read r.m.s value and in case of D.C measurement the meter will read average value.

10. Ans: (a) Sol: In moving Iron instrument I2

2

1

=

2

2

1

I

I =2

5.01

2 = 4100

41 = 25 V

11. Ans: (d) Sol: If torque to weight ratio is high then the

pointer deflects for even small signals.

Torque / weight ratio indicates sensitivity (fast response).

12. Ans (c) Sol: The temperature error can be reduced by

providing a swamping resistor in the basic meter.

Swamping resistor is a alloy of manganin and copper in the ratio of 20:1.

13. Ans: (a) Sol: In PMMC instrument, the deflection torque

will be produced by current in the coil. In electronic meters the deflection is depends on voltage phenomena.

14. Ans: (d) Sol: Electrostatic voltmeters are very suitable to

measure high voltages.

F = dx

dcV 2

21

15. Ans: (c) Sol: In PMMC meter, control torque is provided

by springs and these springs are in series with supply input.

16. Ans: (c) Sol: Time of response depends on damping

system (i.e over damped, under damped and critically damped)

17. Ans: (c)

Sol: CK

B

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