PAPER-II ELECTRONIC SCIENCE Signature and Name of Invigilator
1.
(Signature) OMR Sheet No. ............................................... (To be filled by the Candidate)

(Name)
Roll No.


2.
(Signature) (In figures as per admission card)




(Name) Roll (In words)
D 8 8 1 4

Time 1 1/4 hours] [Maximum Marks 100
Number of Pages in this Booklet 12 Instructions for the Candidates
1.
Write your roll number in the space provided on the top of this page.

2.
This paper consists of fifty multiple-choice type of questions.

3.
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To have access to the Question Booklet, tear off the paper seal on the edge of this cover page. Do not accept a booklet without sticker-seal and do not accept an open booklet.
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After this verification is over, the OMR Sheet Number should be entered on this Test Booklet.


4.
Each item has four alternative responses marked and You have to darken the circle as indicated below on the correct response against each item.


Example

where is the correct response.

5.
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6.
Read instructions given inside carefully.

7.
Rough Work is to be done in the end of this booklet.

8.
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9.
You have to return the test question booklet and Original OMR Sheet to the invigilators at the end of the examination compulsorily and must not carry it with you outside the Examination Hall. You are, however, allowed to carry original question booklet and duplicate copy of OMR Sheet on conclusion of examination.

10.
Use only Blue/Black Ball point pen.

11.
Use of any calculator or log table etc., is prohibited.

12.
There is no negative marks for incorrect answers.


Number of Questions in this Booklet 50
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2.
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4.
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ˆ¤üÖÆü¸üÞÖ

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6.
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7.
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8.
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D-88-14



1 P.T.O.
ELECTRONIC SCIENCE
Paper II

Note This paper contains fifty objective type questions of two marks each. All questions are compulsory.
1. The threshold voltage of an n-channel MOSFET can be increased by

increasing the channel dopant concentration


reducing the channel dopant concentration


reducing the gate oxide thickness


reducing the channel length


2. The Thevenin's equivalent across AB is












3. The input to a differentiator is V. Its output will be

square wave 0 V


V sine wave


4. In successive approximation converter input to the comparator is through

DAC Latch


Flip-flop Sample and hold circuit


5. The assembler directive used to give name to some value or symbol for 8086 ASM-86 is

DD NAME


EQU PROC


6. Which of the following is not an infinite loop

int i for
while



i




int t f inty, x 0
while do




f while
7. In a two cavity Klystron the secondary cavity is called

Buncher Velocity modulation


Coupled cavity Catcher


8. In FM

carrier never becomes zero


J-coefficient occasionally are negative


total power remains constant with respect to modulation index


pulse rate decreases


di
9. In thyristor failure is prevented by
dt

putting L in series with anode putting R in series with anode


putting C in series with anode putting RC in series with anode


10.
The driving point impedance of a network has pole zero plot as shown, if then

11.
The C.E. configuration is normally preferred because it provides

i. voltage gain
ii. current gain
iii. power gain
iv. stability
Which is correct


ii ii, iii


ii, iii ii, iii, iv



12.
An element between the two terminals of a network to which a connection can be made is called while the branches of the tree are called

i. branch
ii. node
iii. twig
iv. loop
Which is correct


ii ii, iii


iii, iv iv



13.
Consider the following statements regarding an RC phase shift oscillator

i. amplifier gain is positive.
ii. amplifier gain is negative.
iii. phase shift introduced by the feedback network is 180°.
iv. phase shift introduced by the feedback network is 360°.
Which is correct


ii ii, iii


iii iv



14.
Read the following statements

i. Gate is a combinational logic.
ii. JK Flip-flop in toggle mode is not combinational logic.
iii. MSJK FF suffers from race-around.
iv. Counters are sequential circuits.
Which is correct


ii ii, iv


ii, iii, iv ii, iii



15.
Which of the following peripherals provide I/O facilities

i. 8279 ii. 8155
iii. 8259 iv. 8255

ii ii, iii


iii, iv ii, iv



16.
The three types of loops available in C language are

i. for
ii. while
iii. do-while
Which loops do not operate without testing the condition even once


iii ii


ii, iii ii, iii



17.
A PIN diode can not be used as

i. Microwave switch
ii. Microwave mixer
iii. Microwave detector
Which is correct


ii ii, iii


iii ii, iii



18.
Read the statements



3(s s2 2s 3 2(s s2 2s 2
3(s s2 2s 2 2(s s2 2s 2
D-88-14 3 Paper-II

i. DSB has two side bands and SSB has one
ii. DSB has carrier and two side bands and SSB has a carrier and a side band
iii. DSB has carrier and two side bands and SSB without carrier and two different side
bands.
Which statements are correct


ii ii, iii


iii ii, iii


19. Which of the following are bidirectional devices
i. SCR ii. TRIAC
iii. DIAC iv. SCS

ii ii, iii


ii, iv iv


20. Which of the following transducers are not linear
i. thermistor
ii. thermocouple
iii. IC sensor

ii ii, iii


iii ii, iii


21. Which one of the following is not LED material
1. Ga As 2. Ga P
3. Si 4. SiO
2

1 2 2 3


3 4 1 4


22. Which of the following quantities can not be measured/determined using HALL effect
1. Type of semiconductor or 2. Band gap
3. Diffusion constant 4. Carrier concentration

1 2 2 3


1 4 1 3


23. Which of the following are not the parts of an AM superheterodyne receiver
1. De-emphasis network 2. Mixer
3. IF Amplifier 4. Limiter

1 2 1 3


1 4 2 4


24. The following is true for the multimode graded index fiber
1.
The refractive index varies as a function of radial distance from the centre.

2.
The refractive index undergoes sudden change at the cladding boundary.

3.
It provides better bandwidth and the data rate than the multimode step index.

4.
It provides the better bandwidth and data rate than single mode step index.



1 3 2 4


1 4 3 4


25. A MOSFET differs from the JFET because
1. of the characteristics 2. the MOSFET has two gates
3. the JFET has p-n junctions 4. of the physical reduced size

1 2 1 3


1 4 2 3


26. Match the following List I List II
a.
n p i. 26 mV/I

b.
p-n diode 2

ii.

c.
JFET iii. K(V V)2


D GS GST
d. enhancement MOSFET iv. mass action law
Codes
a bcd


iii i iv ii


ii iv iii i


iv i ii iii


i ii iv iii


27. Match the following List I List II
a.
n-parameters i. O/P voltage varies as the slope of i/p voltage

b.
differentiator ii. Noise division

c.
half-wave rectifier iii. Function of a Q point

d.
integrator iv. series diode clipper


Codes
a bcd


iii i iv ii


ii iii iv i


i iv ii iii


iv iii i ii




28. Match the following List I List II
a.
voltage shunt negative feedback i. increase of CMRR

b.
constant current source ii. O/P voltage attenuated by a factor 1/29 differential amplifier

c.
Phase shift oscillator iii. FSK decoder

d.
PLL iv. decrease of O/P impedance


Codes
a bcd


i iii iv ii


iv i ii iii


iii ii i iv


ii iv iii i



29. Match the following List I List II
a.
I2L i. XOR

b.
high impedance state ii. non-saturation logic

c.
controlled inverter iii. tristate

d.
ECL iv. bipolar logic


Codes
a bcd


i iii iv ii


ii iv i iii


iii ii iv i


iv iii i ii



30. Match the following List I List II
a.
8086 i. 128 byte RAM

b.
8051 ii. 2-key lockout

c.
8279 iii. 3-chip configuration

d.
8085 iv. maximum mode


Codes
a bcd


iii i iv ii


ii i iii iv


iv i ii iii


i iii iv ii



31. Match the following List I List II
a.
associativity i. memory storage

b.
define ii. if-then-else

c.
auto iii. operators with equal precedence

d.
conditional operator iv. define operator


Codes
a bcd


i iii iv ii


iii iv i ii


iv ii iii i


ii iv i iii


32. Match the following
List I List II
a. DSB-SC modulation i. envelope detection
b. SSB-modulation ii. Foster Seeley
c. AM-demodulation iii. Weaver's method
d. Phase-shift detection iv. Balanced modulator
Codes
a b c d
i iv ii iii
iv iii i ii
ii i iv iii
iii ii i iv
33. Match the following
List I List II
a. Snubber circuit i. SCR
b. Inverter ii. High efficiency
c. Phase control dv
iii. dt protection
d. SMPS iv. UJT
Codes
a b c d
iii i iv ii
i iii ii iv
iv ii i iii
ii iv iii i
34. Match the following
List I List II
a. Miller sweep in CRO i. storage oscilloscope
b. Study of transients ii. integrator
c. Kokrotkoff sound iii. phase measurement
d. Lissajous pattern iv. blood pressure
Codes
a b c d
i iii ii iv
iii iv ii i
ii i iv iii
iv ii iii i
Paper-II 8


35. Match the following List I List II
a.
Power efficient transmission i. SSB-SC

b.
Most bandwidth efficient transmission of ii. VSB
voice signal


c.
Simplest receiver iii. FM

d.
Bandwidth efficient transmission of iv. AM
signals with significant d.c. component



Codes
a bcd


i ii iii iv


iii i iv ii


iv ii iii i


ii iv i iii




Directions Q. Nos. 36 to 45
The following items consist of two statements, one labelled as "Assertion and the other labelled as the "Reason You are to examine the two statements carefully and decide if the Assertion and the Reason are individually true and if so whether the reason is a correct explanation of the assertion. Select your answer to these items using the codes given below and mark your answer accordingly.

Codes

Both and are true and is the correct explanation of


Both and are true, but is not the correct explanation of


is true, but is false.


is false, but is true.


36.
Assertion MOS ICs based on MOSFET structure find wide applications in digital

field.
Reason MOS ICs have small size and are easy to fabricate.


37.
Assertion The series pass transistor in a regulator is in class A mode. Reason Class A is a switching mode and yields high efficiency.

38.
Assertion The most commonly used amplifier in S/H circuit is unity gain NINV

amplifier.
Reason At the sampling state signal building is not desired.


39.
Assertion In some applications it is required to delay pulse train by some number

of clock periods. Reason For delay operation serial in parallel out shift registers are useful.

40.
Assertion Interfacing is a technique to make operation of peripheral or I/O device

compatible with that of a micro-processor.
Reason Some peripherals and I/O devices are not TTL compatible.


41.
Assertion uses many data types such as integers (short and long) and float etc. Reason Conversion specifier used for short unsigned integer is lu.

42.
Assertion The two types of optical sources used in transmitter of optical communication link are LED and LASER.

Reason LASERs are costly hence not preferred for small distance low cost systems.

43.
Assertion In applications such as FM and FSK, VCO plays an important role. Reason The frequency control is easily possible by varying d.c. voltage.

44.
Assertion SCR and SCS belong to the thyristor category. Reason What distinguishes SCS from SCR is that SCS is two gate device.

45.
Assertion Oscilloscope provides graphical representation of time varying signals. Reason Bandwidth is the limitation of oscilloscope.


Read the passage and answer the questions 46 to 50 that follow on your understanding of passage
Optical fibre communication is one among the new techniques have come up and are extensively used for communication purposes. The portion of the e.m. spectrum encompasses the optical region falls in the wavelength of 50 nm (Ultraviolet) to approximately 100 µm (Infrared) which includes visible light spectrum from 400 nm (Violet) to 700 nm (Red). The order of frequency corresponding to these wavelengths falls in the range 1014 to 1018 Hz. There are two types of transmission media used for optical communication i.e., atmospheric channel and guided wave channel. Out of the two, guided wave channel provide much more reliable and versatile medium of communication. The medium used for guided channels in optical range are non-metallic guides popularly known as optical fibre. The optical fibre link used for communication applications has several advantages over conventional cupper cable links which makes possible to send much more data over long distances with negligible attenuation. Although some difficulties do exist in the making of optical fibre set and there are some challenges being faced yet this type of communication mechanism has made a great impact in the present scenario.
46. A multimode step-index fibre has glass core (n1 1.5) and fused quartz cladding (n2 1.46), which one of the following is the value of acceptance angle

20.2° 21.2°


22.2° 76.7°


47. Following is not the usual classification of an optical fibre

single mode step index


single mode graded index


multimode step index


multimode graded index


48. When atoms in Direct bandgap semiconductors move from higher energy state to lower energy state and emission of light takes place, the energy of emitted photon is given as

h v12 E2 E1
E



h v12


2
E
1

h v12 E2 E1


h v12 E2 E1


49. Which of the following are the cases of signal attenuation
1.
Splicing

2.
Intermodal Delay

3.
Scattering

4.
Chromatic Dispersion



1 3


2 3


1 4


2 4


50. The following are correct about a semiconductor LASER
1.
It requires population inversion

2.
It has shorter lifetime than LED

3.
It demonstrates spontaneous emission phenomenon

4.
It generates monochromatic incoherent light.
Find out the correct answer




1 2


1 3


1 4


2 4


Space For Rough Work


Paper-II 12
D-88-14