2013 September UGC NET Examination in Electronic Science, Paper II: Previous Years Solved Question Paper Along With Answer Keys

1. The p-n junction diode is a
(A) Passive device
(B) Vacuum device
(C) Unilateral device
(D) Bilateral device
Answer: (C)

2. A semiconductor has ______ temperature co-efficient of resistance
(A) Zero
(B) Positive
(C) Negative
(D) One
Answer: (C)

3. A JFET has
(A) One built-in diode
(B) Two built-in diode
(C) Three built-in diode
(D) Four built-in diode
Answer: (B)

4. The superposition theorem is essentially based on the concept of
(A) Quality
(B) Linearity
(C) Reciprocity
(D) Non-linearity
Answer: (B)

5. A counter that counts in binary from 0000 to 1010 is known as
(A) Binary counter
(B) Decade counter
(C) BCD counters
(D) Mod-10 counter
Answer: (A)

6. A digital multiplexer is a/an
(A) Combinational circuit
(B) Sequential circuit
(C) Amplifier
(D) Memory device
Answer: (A)

7. An 8086 has how many number of flags?
(A) 5
(B) 7
(C) 9
(D) 11
Answer: (C)

8. In 8085, microprocessor, the register which holds the address of the next instruction to be executed is
(A) Instruction registers
(B) Stack pointer
(C) Temporary register
(D) Program counter
Answer: (D)

9. The Pentium III processor is a
(A) 16 bit processor
(B) 32 bit processor
(C) 64 bit processor
(D) 128 bit processor
Answer: (C)

10. Demodulation is a process
(A) Done at the transmitter
(B) Of filtering the carrier
(C) Of removing the sidebands
(D) Similar to modulation
Answer: (B)

11. The terms frequency pushing and pulling are related to
(A) Reflex Klystron
(B) Two cavity klystron
(C) Pulsed radar system
(D) Magnetron
Answer: (D)

12. Out of the following memory types, one that is volatile is
(A) Magnetic disc
(B) Ferrite core
(C) Semiconductor ROM
(D) Semiconductor RAM
Answer: (D)

13. When Q of an antenna increases, the bandwidth
(A) Increases
(B) Decreases
(C) Stays constant equal to zero
(D) Stays constant equal to unity
Answer: (D)

14. The value of intrinsic-stand-off ratio of UJT should be
(A) >1
(B) <1
(C) 0 (zero)
(D) 10
Answer: (B)

15. In a normal ECG waveform which wave has the maximum amplitude?www.netugc.in
(A) P wave
(B) R wave
(C) Q wave
(D) T wave
Answer: (B)

16. The output impedance in an ideal Op-Amp is
(A) Zero
(B) 20 Ω
(C) 60 Ω
(D) Infinity
Answer: (A)

17. What will be the output of the following statements?
int a = 5, b = 2, c = 10, i = a > b
Void main ( )
{print f(“hello”); main ( );}
(A) 1
(B) 2
(C) Infinite number of times
(D) 10
Answer: (C)

18. Which data communication method is used for sending data in both directions at the same time?
(A) Super duplex
(B) Simplex
(C) Half duplex
(D) Full duplex
Answer: (D)

19. The highest data rate in fiber optic communication occurs in
(A) Single-mode fiber
(B) Graded-index fiber
(C) Multimode fiber
(D) Co-axial cable
Answer: (A)

20. Routh’s array for a system is given below:
S4         1          3          5
S3         1          2          9
S2         1          5
S1         –3
S0         5
The system is
(A) Stable
(B) Unstable
(C) Marginally stable
(D) Conditionally stable
Answer: (B)

Assertion-Reason type questions:
The following items consist of two statements, one labelled as ‘Assertion A’ and the other labelled the ‘Reason (R)’. You are to examine these two statements 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 answers to these items using the codes given below and mark your answer sheet accordingly.
(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 and (R) is false.
(D) (A) is false and (R) is true.

21. Assertion (A): In a common base amplifier voltage gain is more than 1.
Reason (R): In a common base amplifier current gain is less than 1.
Answer: (A)

22. Assertion (A): Op-Amp is used for amplification of weak signals.
Reason (R): To rectify EMG signals, precision rectifiers are used.
Answer: (B)

23. Assertion (A): Gray is unweighted code.
Reason (R): Gray code is not self-complementary.
Answer: (A)

24. Assertion (A): TDM and FDM accomplish the same end by different means.
Reason (R): FDM involves simpler instrumentation as compared to TDM.
Answer: (C)

25. Assertion (A): A SSB system is used for broadcasting applications.
Reason (R): The saving of power in SSB system is ≥ 75%.
Answer: (F)

26. Assertion (A): Dual slope A/Dconverter is the most preferred conversion technique employed in most of the digital multimeters.
Reason (R): Dual slope A/D converter provides high accuracy while at the same time suppresses the HUM effect on the input signal.
Answer: (A)

27. Assertion (A): The system of propagation in waveguides is in accordance to field theory.
Reason (R): The system of propagation in transmission line is in accordance with circuit theory.
Answer: (B)

28. Assertion (A): For a function to be odd f(–x) = –f(x).
Reason (R): If a function is odd, its Fourier series only contains cosine terms.
Answer: (C)

29. Assertion (A): A number of thyristors operating in parallel cannot share a common heat sink.
Reason (R): For simultaneous firing of the thyristor opto isolators may be employed in the gate driving circuit.
Answer: (D)

2013 September UGC NET in Electronic Science, Paper II, Question 30

Answer: (C)

31. Consider the following devices:
1. RTL
2. High Speed TTL
3. ECL
The correct sequence of their decrease in power dissipation is
(A) 3, 1, 2, 4
(B) 3, 1, 4 ,2
(C) 1, 3, 2, 4
(D) 3, 2, 4, 1
Answer: (A)

32. Arrange the following in terms of their increasing conductivity:
1. Copper
2. Steel
3. Leather
4. Rubber
The correct sequence is
(A) 4, 3, 2, 1
(B) 4, 3, 1, 2
(C) 3, 4, 2, 1
(D) 2, 1, 3, 4
Answer: (A)

33. Following are the EM waves:www.netugc.in
1. Red colour light
2. Blue colour light
3. Microwaves
4. X-rays
The correct sequence of decreasing order of wavelength is
(A) 2, 4, 3, 1
(B) 1, 3, 2, 4
(C) 3, 1, 4, 2
(D) 3, 1, 2, 4
Answer: (D)

34. Following are the process steps to fabricate an IC:
1. Crystal growth
2. Epitaxial growth
3. Photo etching
4. Diffusion
5. Vacuum evaporation of Aluminium
The correct sequence of fabrication is
(A) 1, 5, 3, 4, 2
(B) 1, 2, 3, 4, 5
(C) 1, 3, 2, 4, 5
(D) 1, 2, 4, 3, 5
Answer: (B)

35. Following are the modulation/ multiplexing techniques:
1. AM
2. FM
4. WDM
The correct sequence of carrier frequency in decreasing order is
(A) 1, 2, 3, 4
(B) 4, 3, 1, 2
(C) 4, 3, 2, 1
(D) 3, 4, 2, 1
Answer: (C)

36. Match the following:
List – I                        List – II
a. LED                        i. Heavily doped
b. APD                        ii. Coherent radiation
c. Tunnel diode           iii. Spontaneous emission
d. Laser                       iv. Current gain
The correct sequence is given by
a          b          c          d
(A)       ii          i           iii         iv
(B)       iv         iii         ii          i
(C)       iii         iv         i           ii
(D)       iii         ii          i           iv
Answer: (C)

37. Match the following:
List – I                                                List – II
a. Cassegrain antenna                          i. Large B.W.
b. Yagi antenna                                   ii. Direction finding
c. Parabolic reflector antenna              iii. Radar
d. Loop antenna                                  iv. Directional transmission
a          b          c          d
(A)       i           iv         ii          iii
(B)       iii         i           iv         ii
(C)       ii          iv         iii         i
(D)       iii         ii          iv         i
Answer: (B)

38. Match the lists:
List – I                        List – II
(Band gap in eV)        (Materials)
a. 0.67                                     i. Ga As
b. 1.1                           ii. Cadmium sulphate
c. 1.4                           iii. Si
d. 2.4                           iv. Ge
The correct matching order is
a          b          c          d
(A)       iv         iii         i           ii
(B)       iii         ii          i           iv
(C)       iv         i           iii         ii
(D)       ii          iii         i           iv
Answer: (A)

39. Match the following:
List – I                                                            List – II
a. Voltage series feedback connection            i. increases input impedance
b. Voltage shunts feedback connection          ii. Decreases the input impedance
c. Current series feedback connection            iii. Increases the output impedance
d. Voltage series feedback connection           iv. Decreases the output impedance
The correct matching order is
a          b          c          d
(A)       iv         ii          iii         i
(B)       iv         ii          i           iii
(C)       i           iii         iv         ii
(D)       i           ii          iii         iv
Answer: (D)

40. Match the following lists:
List – I                                    List – II
a. Electromyogram                  i. Tracing brain waves
b. Electrocardiogram               ii. Tracing of muscular waves
c. Electroencephalogram         iii. Measurement of air in lungs
d. Spirometer                          iv. A record of electrical activity of heart
a          b          c          d
(A)       i           ii          iii         iv
(B)       i           iv         iii         ii
(C)       i           iv         ii          iii
(D)       iv         iii         i           ii
Answer: (C)

41. Match the following:
List – I                                                List – II
a. Removes ac ripple                           i. Zener diode
b. Supplies ac input voltage                ii. Filter capacitor
c. Constant dc output voltage                         iii. No output voltage
d. Filter choke inductor                      iv. Power transformer
a          b          c          d
(A)       ii          iv         i           iii
(B)       i           iv         iii         ii
(C)       iv         i           ii          iii
(D)       ii          iii         i           iv
Answer: (A)

42. Match the following lists:www.netugc.in
List – I                                    List – II
a. Maxwells bridge                  i. Measurement of unknown inductance
b. Hay’s bridge                       ii. Measurement of high Q of coils
c. Schering’s bridge                iii. Precision measurement of capacitance
d. Weins bridge                       iv. To measure frequency
a          b          c          d
(A)       i           ii          iii         iv
(B)       iv         iii         ii          i
(C)       iv         ii          iii         i
(D)       i           iii         ii          iv
Answer: (A)

43. Match the following lists:
List – I                        List – II
a. Gamma rays            i. 400-700 nm
b. Visible light             ii. 1-10 cm
c. Radiowaves iii. 3 × 10+3 m
d. Microwaves            iv. 4 × 10–11 m
a          b          c          d
(A)       i           ii          iii         iv
(B)       iv         iii         ii          i
(C)       iv         i           iii         ii
(D)       ii          iii         iv         i
Answer: (C)

44. Match the List – I and List – II:
List – I                        List – II
(Type of counters)       (No. of flip flops required)
a. Mod-6                     i. 3
b. Mod-11                   ii. 4
c. Mod-31                   iii. 5
a          b          c
(A)       iii         ii          i
(B)       i           ii          iii
(C)       ii          iii         i
(D)       iii         i           ii
Answer: (B)

45. Match the following lists:
List – I            List – II
(Units)             (Quantity)
a. ps/nm/km     i. Attenuation
b. dB/km         ii. Magnetic field
c. cm2/v-s         iii. Dispersion
d. Tesla            iv. Mobility
a          b          c          d
(A)       iv         i           ii          iii
(B)       iii         i           ii          iv
(C)       iii         i           iv         ii
(D)       i           iv         iii         ii
Answer: (C)

Read the paragraph and answer the questions 46 to 50:
P-i-n photodiode contains a layer of intrinsic semi-conductor material sandwiched between p-and-n regions. The depletion layer is wholly contained within the i region. Thickness of the intrinsic region can be adjusted to produce device with optimum sensitivity and frequency response. P-i-n photodiode is most common type of depletion layer photodiode.
The other classes of photodiodes, avalanche photodiodes, are reverse-biased p-n junction diodes that are operated at voltages above the breakdown voltage. Current multiplication of electron-hole pairs generated by the incident electromagnetic radiation occurs due to avalanche process. The photo multiplication factor Mpn is defined as ratio of the multiplied photocurrent Ipm to the photocurrent Ipho at voltage below breakdown where no avalanche multiplication takes place.

46. Semiconductors are sensitive to
(A) Heat
(B) Magnetic field
(C) Light energy
(D) All of the above
Answer: (D)

47. Which of the following elements is a semiconductor?
(A) Germanium
(B) Copper
(C) Carbon
(D) Phosphorous
Answer: (A)

48. When a reverse bias is applied to a junction diode
(A) Potential barrier is lowered
(B) Majority carrier current is increased
(C) Minority carrier current is increased
(D) Potential barrier is raised
Answer: (D)

49. Photo-diode is reverse biased because
(A) Only one side is illuminated
(B) Majority swept are reverse biased across the function
(C) Reverse current is small as compared to photo current
(D) Reverse current is large as compared to photocurrent
Answer: (C)

50. Avalanche photodiodes are preferred over PIN diodes in optical communication systems because of
(A) Speed of operation
(B) Higher sensitivity
(C) Larger bandwidth
(D) Larger power handling capacity
Answer: (D)