UGC NET 2014: December, Paper II, Electronic Science
Text of page 1
PAPER-II
ELECTRONIC SCIENCE
Signature and Name of Invigilator
1. (Signature) __________________________ OMR Sheet No. : ...............................................
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(Name) ____________________________ (In figures as per admission card)
Roll No.________________________________
D 8 8 1 4 (In words)
Time : 1 1/4 hours] [Maximum Marks : 100
Number of Pages in this Booklet : 12 Number of Questions in this Booklet : 50
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D-88-14 1 P.T.O.
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ELECTRONIC SCIENCE
Paper – II
Note : This paper contains fifty (50) objective type questions of two (2) marks each. All
questions are compulsory.
1. The threshold voltage of an n-channel MOSFET can be increased by
(A) increasing the channel dopant concentration
(B) reducing the channel dopant concentration
(C) reducing the gate oxide thickness
(D) reducing the channel length
2. The Thevenin’s equivalent across AB is
(A) (B)
(C) (D)
3. The input to a differentiator is –5 V. Its output will be
(A) square wave (B) 0V
(C) +5 V (D) sine wave
4. In successive approximation converter input to the comparator is through
(A) DAC (B) Latch
(C) Flip-flop (D) Sample and hold circuit
5. The assembler directive used to give name to some value or symbol for 8086 ASM-86 is
(A) DD (B) NAME
(C) EQU (D) PROC
Paper-II 2 D-88-14
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6. Which of the following is not an infinite loop ?
(A) int i = 1; (B) for (; ;) ;
while (1)
{
i ++
}
(C) int t = 0, f ; (D) int y, x = 0 ;
while (t) do
{ {
y = x;
f = 1; }
} while (x = = 0);
7. In a two cavity Klystron the secondary cavity is called
(A) Buncher (B) Velocity modulation
(C) Coupled cavity (D) Catcher
8. In FM
(A) carrier never becomes zero
(B) J-coefficient occasionally are negative
(C) total power remains constant with respect to modulation index
(D) pulse rate decreases
di
9. In thyristor failure is prevented by
dt
(A) putting L in series with anode (B) putting R in series with anode
(C) putting C in series with anode (D) putting RC in series with anode
10. The driving point impedance Z(s) of a network has pole – zero plot as shown, if
Z(0) = 3, then Z(s) = ?
(A) Z(s) = 3(s + 3) / s2 + 2s + 3 (B) Z(s) = 2(s + 3) / s2 + 2s + 2
(C) Z(s) = 3(s – 3) / s2 + 2s + 2 (D) Z(s) = 2(s – 2) / s2 + 2s + 2
D-88-14 3 Paper-II
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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 ?
(A) i, ii (B) i, ii, iii
(C) ii, iii (D) 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 ?
(A) i, ii (B) ii, iii
(C) iii, iv (D) i, 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 ?
(A) i, ii (B) ii, iii
(C) i, iii (D) i, 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 ?
(A) i, ii (B) i, ii, iv
(C) ii, iii, iv (D) i, ii, iii
15. Which of the following peripherals provide I/O facilities ?
i. 8279 ii. 8155
iii. 8259 iv. 8255
(A) i, ii (B) ii, iii
(C) iii, iv (D) ii, iv
Paper-II 4 D-88-14
Text of page 5
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 ?
(A) i, iii (B) i, ii
(C) ii, iii (D) i, ii, iii
17. A PIN diode can not be used as
i. Microwave switch
ii. Microwave mixer
iii. Microwave detector
Which is correct ?
(A) i, ii (B) ii, iii
(C) i, iii (D) i, ii, iii
18. Read the statements :
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 ?
(A) i, ii (B) ii, iii
(C) i, iii (D) i, ii, iii
19. Which of the following are bidirectional devices ?
i. SCR ii. TRIAC
iii. DIAC iv. SCS
(A) i, ii (B) ii, iii
(C) ii, iv (D) i, iv
20. Which of the following transducers are not linear ?
i. thermistor
ii. thermocouple
iii. IC sensor
(A) i, ii (B) ii, iii
(C) i, iii (D) i, ii, iii
21. Which one of the following is not LED material ?
1. Ga As 2. Ga P
3. Si 4. SiO2
(A) 1 & 2 (B) 2 & 3
(C) 3 & 4 (D) 1 & 4
22. Which of the following quantities can not be measured/determined using HALL effect ?
1. Type of semiconductor (p or n) 2. Band gap
3. Diffusion constant 4. Carrier concentration
(A) 1 & 2 (B) 2 & 3
(C) 1 & 4 (D) 1 & 3
D-88-14 5 Paper-II
Text of page 6
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
(A) 1 & 2 (B) 1 & 3
(C) 1 & 4 (D) 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.
(A) 1 & 3 (B) 2 & 4
(C) 1 & 4 (D) 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
(A) 1 & 2 (B) 1&3
(C) 1 & 4 (D) 2&3
26. Match the following :
List – I List – II
a. n∗p i. 26 mV/I
b. p-n diode 2
ii. |Vp| IDS ⋅ IDSS
c. JFET iii. ID = K(VGS – VGST)2
d. enhancement MOSFET iv. mass action law
Codes :
a b c d
(A) iii i iv ii
(B) ii iv iii i
(C) iv i ii iii
(D) 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 b c d
(A) iii i iv ii
(B) ii iii iv i
(C) i iv ii iii
(D) iv iii i ii
Paper-II 6 D-88-14
Text of page 7
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 b c d
(A) i iii iv ii
(B) iv i ii iii
(C) iii ii i iv
(D) ii iv iii i
29. Match the following :
List – I List – II
a. 2
IL i. XOR
b. high impedance state ii. non-saturation logic
c. controlled inverter iii. tristate
d. ECL iv. bipolar logic
Codes :
a b c d
(A) i iii iv ii
(B) ii iv i iii
(C) iii ii iv i
(D) 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 b c d
(A) iii i iv ii
(B) ii i iii iv
(C) iv i ii iii
(D) 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 b c d
(A) i iii iv ii
(B) iii iv i ii
(C) iv ii iii i
(D) ii iv i iii
D-88-14 7 Paper-II
Text of page 8
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
(A) i iv ii iii
(B) iv iii i ii
(C) ii i iv iii
(D) 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
(A) iii i iv ii
(B) i iii ii iv
(C) iv ii i iii
(D) 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
(A) i iii ii iv
(B) iii iv ii i
(C) ii i iv iii
(D) iv ii iii i
Paper-II 8 D-88-14
Text of page 9
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 b c d
(A) i ii iii iv
(B) iii i iv ii
(C) iv ii iii i
(D) ii iv i iii
Directions : Q. Nos. 36 to 45 :
The following items consist of two statements, one labelled as “Assertion (A)” and the other
labelled as the “Reason (R)”. You are to examine the two statements carefully and decide if the
Assertion (A) and the Reason (R) 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 :
(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 the correct explanation of (A).
(C) (A) is true, but (R) is false.
(D) (A) is false, but (R) is true.
36. Assertion (A) : MOS ICs based on MOSFET structure find wide applications in digital
field.
Reason (R) : MOS ICs have small size and are easy to fabricate.
37. Assertion (A) : The series pass transistor in a regulator is in class A mode.
Reason (R) : Class A is a switching mode and yields high efficiency.
38. Assertion (A) : The most commonly used amplifier in S/H circuit is unity gain NINV
amplifier.
Reason (R) : At the sampling state signal building is not desired.
39. Assertion (A) : In some applications it is required to delay pulse train by some number
of clock periods.
Reason (R) : For delay operation serial in parallel out shift registers are useful.
D-88-14 9 Paper-II
Text of page 10
40. Assertion (A) : Interfacing is a technique to make operation of peripheral or I/O device
compatible with that of a micro-processor.
Reason (R) : Some peripherals and I/O devices are not TTL compatible.
41. Assertion (A) : ‘C’ uses many data types such as integers (short and long) and float etc.
Reason (R) : Conversion specifier used for short unsigned integer is % lu.
42. Assertion (A) : The two types of optical sources used in transmitter of optical
communication link are LED and LASER.
Reason (R) : LASERs are costly hence not preferred for small distance low cost
systems.
43. Assertion (A) : In applications such as FM and FSK, VCO plays an important role.
Reason (R) : The frequency control is easily possible by varying d.c. voltage.
44. Assertion (A) : SCR and SCS belong to the thyristor category.
Reason (R) : What distinguishes SCS from SCR is that SCS is two gate device.
45. Assertion (A) : Oscilloscope provides graphical representation of time varying signals.
Reason (R) : 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 ?
(A) 20.2° (B) 21.2°
(C) 22.2° (D) 76.7°
Paper-II 10 D-88-14
Text of page 11
47. Following is not the usual classification of an optical fibre :
(A) single mode step index
(B) single mode graded index
(C) multimode step index
(D) multimode graded index
48. When atoms in Direct bandgap semiconductors move from higher energy state (E2) to
lower energy state (E1) and emission of light takes place, the energy of emitted photon is
given as
(A) h v12 = E2 – E1
E2
(B) h v12 = E
1
(C) h v12 > E2 – E1
(D) 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
(A) 1 & 3
(B) 2 & 3
(C) 1 & 4
(D) 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 :
(A) 1 & 2
(B) 1 & 3
(C) 1 & 4
(D) 2 & 4
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D-88-14 11 Paper-II
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