TEST BOOKLET

DO NOT OPEN'TlItS TEST BOOKLET UNTIL YOU ARE ASKED TO DO SO
Test Booklet Series
Serial No, 908174

B
BAC-36

ELECTRICAL ENGINEERING
Time Allowed: 2 Hours Maximum Marks: 300
INSTRUCTIONS TO CANDIDATE
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4.
You have to enter your Roll No. on the Test Booklet 1


r
in the Box provided along side. DO NOT write
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5.
This Test Booklet contains 120 items (questions). Each item comprises four responses (answers). You will select the response which you want to mark on the Answer Sheet. In case you feel that there is more than one correct response, mark the response which you consider the best. In any case, choose ONLY ONE response for each item.

6.
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7.
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8.
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9.
After you have completed filling in all your responses on the Answer Sheet and the examination has concluded, you should hand over to the Invigilator the Answer Sheet, the Test BookIet issued to you.


IDO NOT OPEN THIS BOOKLET UNTIL YOU ARE ASKED TO DO SO I
1. The structure of a multi-layered integrated circuit is determined by

Removing successive layers of the circuit.


The intensity of backscattered or secondary electrons is detected by first or second detector.


Surface of the integrated circuit is a flat layer of semiconductor substrate material having implanted doped areas, the surface is covered with a metallisation layer providing a Schottky barrier.


All 3 of above.


2. The Laplace transform of e-3t Cos is




3i 16


4(s


7(s 3)2


3. For a difference equation c(k c r the system's impulse response is

z-l 1 0.5 z-l


2/1 z-I


4. According to the sampling theorem, the critical sampling period T is related with maximum frequency fas
m

T l/fm


T 1/2 f


m

5. A system is said to be causal if

the system has right half poles.


the region of convergence include unit circle.


the region of convergence outside the unit circle.
the system has proper rational function.



. 5
6. The Inverse z-transform of 1 0,2 Z-l is
5 (0.2)k =0.2
+0.2 =0.2
Series-B Z BAC-36
7. The waveform shown has



="vfr

Even symmetry Halfwave symmetry


Odd symmetry No symmetry


8. The average value of a signal 2 3 cos (1011: t 4 cos (20 1t t is

5 002

9. If H and flt) H then
H *F2(w)].This is the property of Fouriertransform as

Time shifting Frequency shifting


Frequency convolution Time convolution


10. What are the time constants of the following systems
28
=0.4 s 1 =5s 2


0.4,5 5,1.6


0.4,2.5 0.4,4


11. Given 2 4 R (s).What is e if the input signal is a step input of magnitude 2
ss
3 6
1.5 2
12. The poles of given closed loop system are Yes)

real complex


on imaginary axis at origin


BAC·36 3 Serles-B
13. Which of these descriptions is true of the step response of an overdamped system?

it rises to a steady state value with no overshoot


it rises to a steady state value with little overshoot


it has an undershoot


it does not settle to a steady state value


14. Which statement is true for given system?
11

I-2s2 +3s 2-s2 0.8s 1
GI and G2 are unstable


GI and G2 are under damped


GI has steady state error but G2 has no error


GI settles faster than G2


15. The root locus for 1/s2 is

a horizontal straight line OJ] the real axis.


a vertical straight line passing through


a vertical straight line passing through


a vertical straight line passing through


16. The transfer function =11(0.01 s is

a lag term


a lead term


a term providing high frequency amplification


none of the above


17. For an Octal decimal number conversion 10 the value of x is

125 215


315 205


18. Which addressing mode is represented by 8085 instruction LDA addr

Indirect Immediate


Absolute Register


Series·B 4 BAC·3(i
19. The 8085 microprocessor has a non-maskable interrupt as

RST 5.5 RST7.5


INTR TRAP


20. Program status word of 8085 microprocessor consists of number of flags as

5 1
21. The stack pointer in a microprocessor is used

to address the stack position of RAM


to address the instruction


to contain the status of accumulator


to contain recoded opcode


22. The B-register in 8751 micro controller is used

as timer register


specially for multiply and divide operations


as control register


as PSW register


23. The ALU can perform the function

Add with or without carry AND, OR, XOR


Bit complement All the above


24. The LVDT is used for the measurement of

voltage force


pressure displacement


25. A milliameter of 3 Q resistance reads a maximum current of 150 rnA. It can be used as a voltmeter to read upto 15 V by

connecting a resistance of 100 Q in parallel with meter


connecting a resistance of 57 Q in parallel with meter


connecting a resistance of 150 Q in series with meter


connecting a resistance of 97 Q in series with meter


BAC·36 5 Series-B
26. The deflecting torque of a moving coil instrument depends on

supply frequency inverse of area of coil


flux in the coil square of the voltage


27. Which transducer has very nonlinear and high temperature characteristics?

thermistor thermocouple


pyrometer thermometer


28. Lissajons figures asppear on eRO screen

when two sine waves of same frequency are applied depend on amplitude of two input signals.


depend on amplitude of two input signals.


depend on phase of two input signals.


used to measure harmonics.


29. The Q-meter is an instrument

to measure inductance


to measure capacitance


to measure ratio of reactance to resistance


to measure frequency


30. Which is not measured by frequency meter?

time period frequency


phase ratio of frequencies


31. The fast Fourier transform analysis can be measured using

distortion meter spectrum analyser


power meter data acquisition system


32. In a full bridge rectifier circuit, with rectifier on the secondary of the transformer, the dc output voltage is

2Vsec(peak/3.l4 Vsec(peak/3·14


2Vsec(peak) 3.14Vsec(peak)


Series·B 6 BAC·36
33. In a clipper circuit with silicon diode and bias of V volts, the clipping level is
0.7 V 0.7
V 2V 0.7
34. A 6V zener diode is used to provide voltage regulation with a series resistance of 100 Ohms and supply voltage is 12V. When under no load the power dissipated in the zener diode is

60mW 36mW


360mW 3600mW


35. In a transistor biasing circuit with voltage divider bias circuit, if the operating point is on the left on the load line.

peak of the input voltage is clipped.


one side peak of the output voltage is clipped.


both positive and negative peaks are clipped.


there will be a distortion in the middle.


36. In a differential amplifier the differential voltage gain is 500 and the common mode voltage gain is 0.5. The CMRR indB is

80 60


30 20


37. In a bipolar transistor when in saturation, the de current gain is

less than greater than


equal to zero


38. An OP amp has an open loop gain of 1,00,000. If the feedback fraction is 0.02, the approximate closed loop gain is

I 1,00,000


50 0.02


39. An OP amp has a slew rate of IV/J,A.s. At a signal frequency of 0.1 MHz, the maximum undistorted sine wave amplitude is

8V 4.82 V


2.02 V 1.592 V


BAC·36 7 Series-B
40. In a Butter worth second order low pass filter with =lKohms, C=C=O.OOIF,
1 1 2
the cut off frequency is
1KHz 100KHz
0.157Hz 1.57Hz

41. If 2 variables A and B are given to a 2 input NOR gate, the output is equivalente to
A A'·
AI A·B
42. The sum of product expression for a Boolean function can be derived from its truth table by

AND operation of the product terms.


NOR operation of the product terms.


OR operation of the product terms.


NAND operation of the product terms.


43. IN TTL Ics the protective diode is used to limit the

positive excursion to 0.7V


negative excursion to -o.7V


positive excursi"on to 0.3 V


negative excursion to -0.3 V


44. A full adder is a combinational circuit that performs the arithmetic sum of three input bits and produces a

sum output sum output and a carry


sum output with two carries two sums with two carries


45. A 1 to 16 demultiplexer has

2 select inputs 3 select inputs


4 select inputs, 8 select inputs .


46. To convert a S-R flip-flop to D flip-flop

D input is given to S and D input to clock


D input is given to Sand D to R


D input is given to clock and D to S input


D input to S and clock to R Serles·B 8 BAC·36


. 47. A modul0--6 ripple counter with J-K flip-flops uses at the clear input, the output from


NAND gate with QB,QC as inputs


NAND gate with QBas inputs


NAND gate with Qas inputs


AND gate with as inputs


c
48. Ina32x8ROMthereare

8 address lines 5 address lines


4 address lines 32 address lines


49. A binary ladder with R-2R network has R 20K Ohms. The total resistance looking out toward the LSB input is

20KOhms 40KOhms


IOKOhms 30KOhms


50. A rectangular waveform has fifth harmonic amplitude

same as that of fundamental


0.2 times that of fundamental


0.4 times that of fundamental


5 times that of fundamental


51. A amplitude modulated wave has E of IOV and E . of 5V. The modulation index is
max mm

3 1/3


1 2


52. In PM demodulation hard limiter and band pass filter are used to remove

frequency variation in the PM wave


amplitude variation in PM wave


noise in the demodulated wave


amplitude variations in demodulated wave


BAC-36 9 Series-B
53. Digital modulation can withstand channel noise and distortion better than analog schemes.

as long as the channel noise is within limits


for any noise


for thermal noise only


statement is not true


54. In pulse code modulation the effect of quantization is to

remove noise


introduce additional noise


limit noise in the channel


remove noise in the limiter


55. In phase shift keying the power required is

3dB more than in ASK


3dB less than in ASK


6dB less than in ASK


6dB more than in ASK


56. The cumulative distribution function has a maximum value of

2 unity


1.5


57. In digital modulation, if the phase in the received RF pulse is unknown

coherent detection can be used


coherent detection cannot be used


envelope detection cannot be used


non coherent techniques cannot be used


58.
In some of the channel coding schemes such as in NRZ, with long strings of or

59.
Attitude control in satellites is necessary for pointing to the desired regions on earth


information is gained synchronization may be lost synchronization is achieved all the information is lost
Serles·B 10 BAC-36


the power supplies


the amplifiers


the directional antennas aboard


the motors


60. In cellular scheme, the frequency reuse is done in all the cells

adjacent to the cell


except in those immediately adjacent cells


within a city


having low power transmitters


61. In television receiver a dc restorer is used before applying the signal to

speaker picture tube


audio amplifier IF amplifier


62. The core of a transformer (medium size) uses to provide high flux densities

diamagnetic paramagnetic


ferromagnetic core none of these


63. Laminations in the transformer core are provided to avoid

continuous air gap to reduce the weight


to reduce exiting current to reduce copper losses


64. A three phase transformer can be used in emergency at reduced rating of 58% to deliver three phase power when it is connected

in star-delta delta-star


star-star delta-delta


65. In a d.c. machine the force on a conductor placed on the periphery of the conductor is
directly proportional to parallel path
inversely proportional to the parallel path
inversely proportional to the length of the conductor
none of these

BAC·36 11 Series·B
66. The large d.c. motors used in steel rolling mills are always provided with compensating windings for

opposing the armature mmf maintaining the voltage


maintaining the speed none of these


67. In an induction motor high rotor resistance is required for

Power factor and low starting current


high power factor and high starting current


high power factor and low starting current


low slip and high efficiency


68.. A synchronous motor at no load condition is known as synchronous condenser and improves the

stability


efficiency


powerfactor


frequency of the integrated system


69. Hunting is highly undesirable in synchronous machines and to minimize hunting we can use

Damper bars reduce air gap


use salient poles use inter poles


70. Linear synchronous motors are used in

Low speed vehicles high speed vehicles


medium speed vehicles none of these


71. Brushless D.C. motors arc used in

robotics refrigerators


airconditioners centrifuges


72. Single phase series motors are widely used in domestic appliances and operate at speeds

500 to 1000 rpm 1500 to 10,000 rpm


15,000 to 20,000 rpm 50 to 100 rpm


Series-B 12 BAC·3fj
73. A type of conductor known as expanded ACSR has a filler separating inner steel strands from outer aluminium strands and this filler is

mica sheet cotton tape


paper tape aluminium foil


74. Ifthe diameter of the current carrying conductor increases then the corona loss

increases decreases


remains unchanged none of these


75. Transposition of communication and power lines reduces the induced voltages due to electrostatic and electromagnetic induction to a considerable extent. The lines shall be transposed to of the length in one barrel.
1/4 1/5
1/6 1/3
76. In river crossing, hilly terrain, modem HV lines have span more than
50 m 100 m
500m 00

77. One of the most powerful tool for dealing with unbalanced polyphase circuit is the method of symmetrical components introduced by the scientist

Gauss Volta


Newton C.L. Fortescue


78. Surge impedance loading of power transmission line is the power delivered to a purely

inductive


capacitive


resistive load equal to surge impedance


none of these


I
79. If the transmission line is loaded with leading reactive volt amperes, there will be rise of

voltage at the receiving end and this

increases


decreases


remains same with the increase in the length of line


none of these


BAC-36 13 Series-B
....

so. The rate of rise of transient recovery voltage depends upon the circuit

power factor voltage


frequency breaking current


81. Plug Setting Multiplier is the ratio of

secondary current/relay current


secondary current/primary current


secondary current/relay current setting


none of these


82. Merz-Price protection is used for protection of

transmission line transformer


generator none of these


83. SCR turns off whenever

the supply voltage becomes zero


the gate current becomes zero


the anode current becomes less than the holding current


the anode current is less than latching current


84. The voltage snubber circuit are used

to protect the device from high voltage spikes


to prevent unwanted triggering of power semiconductor devices


for triggering of thyristors without gate triggering


both and


85. The second break down in power BIT occurs due to

The first break down and the formation of hot spot inside


excessive collector current and low collector emitter voltage


excessive base current and high collector emitter voltage


none of thee above


14 BAC·36
86. The requirement of the gate drive circuits for power MOSFET and IGBT is

high source capability high sink capability


both and high voltage capability


87. For high inductive load of a single phase full converter, THD of the line current is

90.9% for the switching angle a:5 90°


50% for a 90°


48.3% for any value of a


24.3% for any value of a


88. In an isolated output fly back converter, the high frequency transformer used works as an inductor

during tum....<Jn period of the switching device


during tum off period of the switching device


during both


none of these


89. A motor load system is stable when the slope of the torque speed characteristics of the motor is

higher than the slope of the torque speed characteristics of the load


lower than the slope of the torque speed characteristics of the load


zero


none of the above


90. Voltage control method'employed for speed control of induction motors is most effective for

A constant torque load only fan type load only


for traction load only none of the above


91. For a closed loop controlled d.c. drive, current limit control is normally employed

for speed control at starting


for acceleration both and


BAC-36 15 Serles-B
92. In the circuit shown below, the magnitudes of VI and Vc are twice that of Vr The inductance of the coil is
SO V.


2.14mH


3.18 mH


93. In the .circuit shown below, the switch S is closed at time t =O. The voltage across the inductance at t is
30
S
4F

4H
40
40

lOY

2V 4V


-6V 8V


94. Two AC sources feed a common variable resistive load as shown below. Under the
maximum transfer condition, the power absorbed by the load resistance Rt is
60 j80 60 j80


2200W
1000 W
95. For three-phase circuit show below the ratio of currents IR:ly:IB is given by R I.
B I.

Y Iv

1:1:V3


I


Series·B 16 BAC·36
1250 W


96.


Rln2_I nRln2-1


n2Rln2-1 none


97. For the circuit shown in below, identify the correct statement, where Z. is z-parameters of
top circuit, is Z parameters of bottom circuit and Z is Z parameters of complete circuit.
In In
In In In

For any value of RI and R2 Z =Z.


IfRI then only Z =Z.


If R1 and R2 is equal to IQ then only Z =Z.


None


2
98. Consider the following statements regarding an RC differentiating network shown below:
1.
For an applied rectangular pulse. the output is spiky in nature for RC « pulse duration.

2.
The output is a ramp for rectangular input pulse.

3.
The output has zero average value for all inputs
Of these statements



c





1.2,3 are correct 1 3 are correct
2 3 are correct 1 2 are correct
BAC·36 17 Serles-B



99. In the circuit shown below, switch is closed at t 0 with the crrcuit previously unenergized. The circuit constants areL lH, =4H,Rj =IV.
1
The expression for is
M



•

J.-(21S)e-uS





100. Using Gauss law in integral form, electric field due to the following volume charge distribution in Cartesian:
{izi Iz[ a
Izi>a


z312folzl forlzl a 2 [zlJ2foz iz for Izi a


z2l2folz[ for Izl a2lz[l2foz ifor a


z z

Iz31J2fz for Izl a 2 IzIJ2Ez ifor Izi a

oz oz


z312folzl for Izi a 2 zJ2fOZ ifor Izi a


z z
101. A filamentary wire closely wound in the form of a spiral in the xy plane, starting at the origin and ending at radius carries a current I in direction. Consider the tum density to be an arbitrary function of and show that magnetic flux density at a point is given by
a a

B l!oI/2 r;0 f z2)312i&m IT 0 f dr)i

zz aa


B 0 f z2p12 i& m IT f or dr)iz


z aa

B l!oI/2 0 f or z2)312 i& m =IT 0 f dr)i

zz aa


B f z2)312) i& m IT 0 f dr)i


z z
Series·B 18 BAC-36
102. Electric and magnetic fields are given in cylindrical by
VcI cok cosrot if



o otherise
sin sinrot a b

B

o otherise Where 10, ro and ro EO are constants. Find the expression for the power leaving the volume bounded b two constant z planes, one of which is the z plane,

VoIrfZ VoIrf4


VoIrf6 VoIrf8


103. A resonator is formed by placing perfect conductors in two transverse planes z and z d of a parallel plate wave-guide of spacing Find the resonant frequency corresponding to TEM, I modes
z


x'· z=o
z=d
x-O
fm,o.! l/z..Jl.l.d(m1a)2
f +..J(l/dl
mo

fm,o.l


f m,o. ..J(l/d)3


104. A cavity resonator with an open end functions as a

unidirectional antenna, sending or receiving RF energy to/from the direction of the open end.


bi-directional antenna, sending or receiving RF energy to/from the direction of the open end.


unidirectional antenna, sending or receiving EM waves to/from the direction of the open end.


bi-directional antenna, sending or receiving EM waves to/from the direction of the open end.


BAC·36 19 Serles-B
105. Which of the following statements is true?

At resonance, the series impedance of the two elements is at a minimum and the parallel impedance is a maximum.


At resonance, the series impedance of the two elements is at a maximum and the parallel impedance is a minimum.


At resonance, the series impedance of the two elements is at a minimum and the parallel impedance is a minimum.


At resonance, the series impedance of the two elements is at a maximum and the parallel impedance is a maximum.


Only 1 is correct 1 and 2 are correct


3 and 4 are correct Only 2 is correct


106. Which of the following statements is true?
1.
Polarization is the orientation of the fields where the electric field is oriented along the axis of the antenna and the magnetic field is perpendicular to both the electric field and the direction of propagation.

2.
Polarization is the orientation of the fields where the magnetic field is oriented along the axis of the antenna and the electric field is perpendicular to both the electric field and the direction of propagation.

3.
Polarization is the orientation of the fields where the magnetic field is oriented along the axis of the antenna and the electric field is perpendicular to both the magnetic field and the direction of propagation.



only 1 is correct only 2 is correct


only 3 is correct none


107. The electric break-down strength of materials is dependent on

Composition Thickness


Moisture content All the above


1 is correct 1 and 2 are correct


2 and 3 are correct only 4 is correct


108. Materials having a high dielectric constant, which is non-linear are known as

Super dielectrics Elastomers


Ferromagnetics Hard dielectrics


Series·B 20 BAC·36
109. The dielectric strength of ferromagnetic materials depends to a large extent on

Intensity of electric field


Presence of magnetic materials in vicinity


Area of hysterisis loop for materials


Frequency of applied voltage


110. Piezo-electric materials serve as a source of

Microwaves Ultrasonic waves


Musical waves Resonant


111. Piezo-electricity provides with a means of converting

Electrical to Mechanical Mechanical to Electrical


Electrical to Magnetic Magnetic to Electrical


112. Magnetic materials used in Hard disc, Floppy disc are

NiCo, CuNiFe, Cr02,Fep3


NiCo, CNiFe, cr02' Fe20 3


NiCu, CuNiFe, cr02' Fep3


NiCo, CuNiFe, cr02' Fep2


113. SmCo' Sm2Co17, NdFeB(= can be used in
s

Videotape Sensors


Mu-metal Floppy disc


114. The concentrations of electrons and holes in an intrinsic (i.e. pure) semiconductor, ni and pi, are equal and may be calculated from the expression where Eg is the forbidden energy gap, or bond strength, of the semiconductor, which on an energy band diagram is the energy separation between the conduction and valence bands; kB is boltzmann's constant. Nand Nare the effective densities states.
cv

N )112 exp(-E 12k


N i exp(-E 12k


N )112 exp(-E *2k


N )312 exp(-E 12k


cv gg
cv gg
cv gg
cv gg
BAC·36 21 Serles·B
115. The following steps are involved in wafer cleaning procedure

Removal of residual organic contaminants only


Stripping of thin hydrous oxide film only


Desorption of remaining atomic contaminants


All the 3 above


116. For integrated circuits photolithographyis used to remove areas of a protective layer so that

Chemical reactions can take place in exposed areas.


Chemical reactions can take place in unexposed areas.


Chemical reactions can take place in transparent areas.


Chemical reactions can take place in translucent areas.


117. Dry etching refers to removal of material, typically a masked pattern of semiconductor material, by exposing material to bombardment of ions which contain

Plasma of nitrogen, chlorine and boron trichloride


Plasma of sodium, chlorine and boron trichloride


Plasma of nitrogen, phosphorous and boron trichloride


Plasma of nitrogen, chlorine and boron trioxide


118. SiN is used in semiconductor industry such as a diffusion mask during device processing, a dielectric for memory devices because it offers a

High breakdown field strength and a low fixed interface charge density.


Low breakdown field strength and a high fixed interface charge density.


High breakdown field strength and a high fixed interface charge density.


Low breakdown field strength and a low fixed interface charge density.


119. The various Si wafer processing steps fall into following categories

Coat Baking Photolithography


Die Attach All of the above


120. Thin films of SiN are well suited as anti-reflection coating for Si solar cells because of their optical properties
Refractive index and Absorption coefficient
Refractive index and Adsorption coefficient
Reflective index and Absorption coefficient
Reflective index and Adsorption coefficient

Serles·B 22 BAC·36
Space For Rough Work
BAC·36 23 Serles·B