2013 September UGC NET Solved Question Paper in Electronic Science Paper 3

1. In UJT, the value of stand-off ratio is

(A) 0.2

(B) 0.4

(C) 0.7

(D) 0.98

Answer: (C)


2. Tunnel diode is basically a junction diode with

(A) High doping in P-region alone

(B) High doping in p and n regions, both

(C) High doping in n region alone

(D) Low doping in both P and n regions

Answer: (B)


3. The condition for a two-port network to be reciprocal is

(A) Z11 = Z22

(B) Y21 = Y22

(C) h21 = h12

(D) h21 = –h12

Answer: (D)


4. An Op-Amp behaves like an ideal Op- Amp upto

(A) Hz

(B) 5 KHz

(C) 5 MHz

(D) 50 MHz

Answer: (B)


5. If the gain of an ideal amplifier decreases, the bandwidth

(A) Increases

(B) Decreases

(C) Remains zero

(D) Remains unaltered

Answer: (A)


6. To use as a memory, which one of the following is more suitable?

(A) Monostablemultivibrator

(B) Bistablemultivibrator

(C) Astablemultivibrator

(D) Schmitt trigger

Answer: (B)


7. NAND gate is also called as

(A) Bubbled AND gate

(B) Bubbled OR gate

(C) Bubbled NOR gate

(D) Bubbled XOR gate

Answer: (B)


8. The INTR pin in 8086 is a

(A) Non-maskableinterruptswww.netugc.com

(B) Maskable interrupt

(C) Priority interrupts

(D) None of the above

Answer: (B)


9. 8085 microprocessor does not have

(A) Zero flag

(B) Sign flag

(C) Parity flag

(D) Overflow flag

Answer: (D)


10. Which mode of 8253 acts as a square wave generator?

(A) Mode-1

(B) Mode-2

(C) Mode-4

(D) Mode-3

Answer: (D)

11. Which of the following program is not a utility?

(A) Debugger

(B) Spool

(C) Editor

(D) Inhibit

Answer: (B)


12. Modulation is a process of

(A) Reducing distortions

(B) Improving thermal stability

(C) Combining audio and radio frequency waves at the transmitter

(D) Generating constant frequency waves

Answer: (B)


13. Which type of modulation causes envelope distortion of a base band signal?

(A) Amplitude modulation

(B) Frequency modulation

(C) Phase modulation

(D) Angle modulation

Answer: (C)


Answer: (C)


15. When microwave signals flow through the curvature of the earth, it is called

(A) Duct position

(B) Faraday’s effect

(C) Raman scattering

(D) Ionospheric scattering

Answer: (A)


16. The Reflex Klystron can be used as

(A) Amplifier only

(B) Oscillator only

(C) Both amplifier and oscillator

(D) Neither amplifier nor oscillator

Answer: (B)


17. Step down regulator produces an output

(A) Low voltage and low current

(B) Low voltage at high current

(C) High voltage at low current

(D) High voltage at high current

Answer: (B)


18. The time base of a CRO is controlled by

(A) Square waveform

(B) Sine waveform

(C) Saw tooth waveform

(D) Staircase waveform

Answer: (C)


19. Routh Hurwitz criterion gives

(A) Phase-details

(B) Marginal stability

(C) Relative stability

(D) Absolute stability

Answer: (D)


20. Photo diode is reverse biased because

(A) Only one side is illuminated

(B) Majority carriers flow under these conditions.

(C) Reverse current is small as compared to photo current

(D) Reverse current is large as compared to photo current

Answer: (C)

21. For PCM, the bandwidth required to transmit a voice channel is

(A) 20 KHz

(B) 5 KHz

(C) 64 MHz

(D) 64 KHz

Answer: (D)


22. In SCR’s snubber circuits employ

(A) Inductor only

(B) A combination of R and L

(C) A combination of R and C

(D) Resistance only

Answer: (C)


23. In optical fiber communication systems, FBG is used for

(A) Dispersion compensation

(B) Long haul communication

(C) Non-linearity management

(D) Source

Answer: (A)


24. In an SCR, dual converter circuit

(A) α1 + α2 = 90°

(B) α1 + α2 = 180°

(C) α1 + α2 = 270°

(D) α1 + α2 = 135°

Answer: (B)


Answer: (C)


26. The Laplace transform of sin2 3t is given by

(A) 18/ [s(s2 + 36)]

(B) 6/ (s2 + 36)

(C) 18(s + 6) / [s(s2 + 36)]

(D) 1/ [6s(s2 + 36)]

Answer: (A)


27. The Fourier Transform of a Gaussian time pulse is

(A) Uniform

(B) A pair of impulse

(C) Gaussian

(D) Rayleigh

Answer: (C)


28. For the Z-transform X (z) = 4z2 + 2 + 3z–1, 0 < |z| < ∞ x(n) is given by

(A) x(n) = 4δ[n – 2] + 2δ[n] + 3δ[(n + 1)]

(B) x(n) = 4δ[n + 2] + 2 + 3δ[n – 1]www.netugc.com

(C) x(n) = 4δ[n + 2] + 2δ[n] + 3δ[n + 1]

(D) x(n) = 4δ[n – 2] + 2δ[n – 1] + 3

Answer: (B)


29. An amplifier has an open loop gain of 100 and its lower and upper hand frequency of 100 Hz and 100 KHz, respectively. A feedback network with a feedback factor of 0.99 is connected to the amplifier; the new lower and uppercut off frequencies are at

(A) fH = 10 MHz and fL = 1 Hz

(B) fH = 25 MHz and fL = 10 Hz

(C) fH = 100 MHz and fL = 100 Hz

(D) fH = 10 MHz and fL = 10 Hz

Answer: (A)


30. How many flip-flops are required to build a digital counter to count from 0 to 1024?

(A) 11

(B) 6

(C) 10

(D) 24

Answer: (A)


31. Negative feedback in amplifier results in

(i) Reduced voltage gain

(ii) Reduced sensitivity

(iii) Decreased bandwidth

(iv) Reduced distortion

Of these statements:

(A) (i) and (ii) are correct

(B) (i), (ii) and (iii) are correct

(C) (i), (ii) and (iv) are correct

(D) (i) and (iv) are correct

Answer: (C)


32. Consider the following statements :

1. Figure of merit and CMRR are the same parameters.

2. In an Op-Amp CMRR is very high approaching to infinity.

3. The input stage of an Op-Amp is usually a differential amplifier

(A) 1, 2, 3 are correct

(B) 2 and 3 are correct

(C) 1 and 2 are correct

(D) 1 and 3 are correct

Answer: (B)


33. Consider the following statements with respect to ECL gates:

(i) ECL represents non-saturated logic

(ii) ECL circuits are easy to interconnect with circuits of other families.

(iii) ECL family employs differential amplifier circuitry.

(iv) ECL has the unique feature of providing two outputs which are complementary to each other.

Among the above, which statements are correct?

(A) (i), (ii) & (iii)

(B) (ii), (iii) & (iv)

(C) (ii), (iv) & (i)

(D) (i), (iii) & (iv)

Answer: (D)


34. A multiplexer :

(i) Selects one of the several inputs and transmits to a single output.

(ii) Routes the data from a single input to one of many outputs.

(iii) Converts parallel data into serial data.

(iv) It is a combinational circuit.

Which one of the following is correct?

(A) (i), (ii) & (iv)

(B) (ii), (iii) & (iv)

(C) (i), (iii) & (iv)

(D) (i), (ii) & (iii)

Answer: (C)


35. Audio signals are not transmitted by EM waves because

(i) Antennas used will be unimaginably lengthy

(ii) Audio signals do not radiate

(iii) Interference is due to simultaneous transmissions.

(iv) Usable frequency range is too low and narrow.

Which of the following is correct?

(A) (i) & (ii)

(B) (ii) & (iii)

(C) (i) & (iii)

(D) (i), (iii) & (iv)

Answer: (C)


Answer: (A)


37. Consider the following statements:

(i) LCD essentially acts as a capacitor.

(ii) LCD has slow decay time.

(iii) LCD’s appear invisible indarkness.

(iv) Twisted nematic LCD segment appears black when it is in ‘ON’ condition.

Which is valid one?

(A) Statements (i) and (ii)

(B) Statements (ii) and (iii)

(C) Statements (ii), (iii) and (iv)

(D) Statements (i), (ii), (iii) and (iv)

Answer: (D)


Answer: (B)


39. Consider the following statements:

(i) Rayleigh Scattering losses are proportional to 1/(λ)4

(ii) The operating frequency of optical fiber is 193 T Hz

(iii) In III transmission windows, the attenuation is 5 dB/km.

Which one is correct?

(A) (i) and (ii)

(B) (ii) and (iii)

(C) (i) and (iii)

(D) (i), (ii) and (iii)

Answer: (A)


40. Consider the following statements in connection with Electrodynamometer type instruments:

(i) They serve as transfer instrument.

(ii) They exhibit square law response.

(iii) They are free from hysteresis.

(iv) They have eddy current damping.

Which are valid?

(A) (i), (ii), (iv)

(B) (i), (ii), (iii)

(C) (ii), (iii), (iv)

(D) (i), (ii), (iii), (iv)

Answer: (B)


Assertion-Reason type questions: Q. 41 to 50: The following items consist of two statements, one labelled as ‘Assertion (A)’and the other labelled the ‘Reason (R)’. Youare to examine these two statements anddecide 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 but (R) is false.

(D) (A) is false and (R) is true.


41. Assertion (A): A step graded junction is formed when there is an abrupt change from acceptor ion on one side to donor ions on the other side.

Reason (R): In step graded junctions, donor and acceptor concentrations are unequal and these junctions behave as asymmetrical junctions.

Answer: (A)


42. Assertion (A): For a positive real function, N(s) must not have any poles in the right half plane.

Reason (R): Re [N(jw)] ≤ 0 for all w

Answer: (C)


43. Assertion (A): In common collector amplifier, voltage gain is greater than unity and this configuration is called as Emitter follower.

Reason (R): Common collector stage is used for impedance matching as its input impedance is very large as compared to output impedance.

Answer: (D)


44. Assertion (A): The TTL 54/74 ALS family has smallest delay power product.

Reason (R): Power consumption in TTL 54/74 ALS is reduced as there is decrease in resistance values and consequently current reduction.

Answer: (C)


45. Assertion (A): The ‘CALL’ instruction is used to transfer program control to a subprogram or subroutine.

Reason (R): The instruction pushes the current programme counter contents on to the stack and loads the given address into the PC, and program control is transferred to the given address in the instruction.

Answer: (A)


Answer: (C)


47. Assertion (A): In quadrature detectors, the two signals are said to be in quadrature if they are at 45° angle.

Reason (R): Quadrature detectors are used to demodulate the FM signals.

Answer: (D)


48. Assertion (A): Silicon controlled rectifiers are PNPN devices, having gate as controlling input.

Reason (R): These devices do notwork on avalanche breakdownprinciple.

Answer: (C)


49. Assertion (A): PIN diodes have wider depletion region, in order to allow light to penetrate more deeply in the semiconductor material.

Reason (R): III-V semiconductor materials are used to fabricate in order to allow shorter wavelength in the region of 400-700 nm.

Answer: (C)


50. Assertion (A): The ‘DO-WHILE’ statement is used less frequently than the while statement.

Reason (R): For most applications, it is more natural to test for continuation of a loop at the beginning rather than at the end of the loop.

Answer: (A)


51. Arrange the following in order of increasing wavelength of output wave :

1. He-Ne laser

2. Nd:YAG laser

3. Laser diode operating in 3rdtransmission window

The correct order is

(A) 3, 2, 1

(B) 2, 3, 1

(C) 1, 3, 2

(D) 1, 2, 3

Answer: (D)


52. Arrange the following in terms of increasing Delay Power Product:

1. TTL 74 AS

2. TTL 74 LS

3. CMOS-74 C

4. ECL 100 K

The correct sequence is

(A) 4, 3, 1, 2

(B) 4, 1, 2, 3

(C) 3, 1, 2, 4

(D) 1, 2, 3, 4

Answer: (B)


53. Arrange the following in terms of increasing frequency:

1. UHF

2. X-Band

3. Sky waves

4. X-rays

The correct sequence is

(A) 3, 1, 2, 4

(B) 1, 4, 3, 2

(C) 4, 3, 2, 1

(D) 2, 3, 1, 4

Answer: (A)


54. Arrange the following in decreasing order of length:

1. 1 mil

2. 1 nm

3. 1 picometer

4. 1 femtometer

The correct sequence is

(A) 4, 3, 2, 1

(B) 1, 2, 3, 4

(C) 2, 1, 3, 4

(D) 4, 3, 1, 2

Answer: (B)


55. There are following blocks :

1. Antenna and RF stage

2. Mixer with Local oscillator

3. Amplifier (class C)

4. IF amplifier

5. Detector

The correct sequence of receiver section is

(A) 1, 2, 3, 4, 5

(B) 5, 1, 2, 3, 4

(C) 1, 2, 4, 3, 5

(D) 1, 2, 4, 5, 3

Answer: (D)


56. In a telemetry system, the correct sequence of transmission system is given by:

1. Information

2. Sensor and signal conditioning

3. Quantisation

4. Encoding

5. Antenna

The correct sequence is

(A) 5, 1, 2, 3, 4

(B) 1, 2, 3, 4, 5

(C) 2, 3, 4, 5, 1

(D) 5, 4, 3, 2, 1

Answer: (B)


57. Arrange the following in order of increasing the input impedances:

1. BJT CE stage

2. BJT in CB stage

3. BJT in CC stage


The correct sequence is given by

(A) 2, 1, 3, 4

(B) 4, 2, 1, 3

(C) 4, 3, 2, 1

(D) 3, 1, 2, 4

Answer: (A)


58. For finding the inverse of a z-transform:

1. Partial fraction expansion

2. Contour integration

3. Convolution

4. Power series expansion

Following is the correct sequence:

(A) 1, 2, 3, 4

(B) 1, 2, 4, 3

(C) 4, 3, 2, 1

(D) 1, 3, 4, 2

Answer: (B)


59. For measuring VSWR,

1. Microwave source

2. Detector amplifier

3. Meter

4. Slotted section

5. Variable attenuator

The correct sequence is

(A) 1, 5, 4, 2, 3

(B) 3, 2, 1, 5, 4

(C) 4, 1, 2, 3, 5

(D) 1, 2, 3, 4, 5

Answer: (A)


60. Arrange the following in order of increasing frequency:

1. L band

2. S band

3. C band

4. K band

The correct sequence is

(A) 4, 1, 2, 3

(B) 4, 3, 2, 1

(C) 1, 3, 4, 2,

(D) 1, 2, 3, 4

Answer: (D)


61. Match the following lists:

List – I                        List – II

a. Early affect             i. IC Fabrication

b. Masking                  ii. JFET

c. Enhancement           iii. MOSFET

d. Pinch off                 iv. Transistor

The correct match is

a          b          c          d

(A)       i           ii          iv         iii

(B)       i           iii         ii          iv

(C)       iv         iii         i           ii

(D)       iv         i           iii         ii

Answer: (D)


62. Match the following lists:

List – I                                    List – II

a. Zeroes & Poles                    i. Linear elements

b. Ramp                                   ii. ABCD

c. Super position                     iii. 1/S2

d. Transmission parameters     iv. Stability

The correct match is

a          b          c          d

(A)       iv         iii         i           ii

(B)       iii         i           ii          iv

(C)       i           ii          iv         iii

(D)       ii          iv         ii          i

Answer: (A)


63. Match the following lists:

List – I                                    List – II

a. Virtual ground                     i. Time constant

b. L/R                                      ii. Q-factor

c. WL/R                                  iii. Op-Amp

d. Intrinsic standoff ratio        iv. UJT

The correct match is

a          b          c          d

(A)       ii          i           iii         iv

(B)       iii         iv         i           ii

(C)       iii         i           ii          iv

(D)       iv         i           ii          iii

Answer: (C)


64. Match the following lists:

List – I                        List – II

a. IC 7410                   i. Hex Inverter

b. IC 7404                   ii. Quad 2 input ORgate

c. IC 7432                   iii. JK master slave flip flop

d. IC 7472                   iv. Triple 3-input NAND gate

The correct match is

a          b          c          d

(A)       iv         ii          i           iii

(B)       iv         i           ii          iii

(C)       i           ii          iii         iv

(D)       ii          iv         i           iii

Answer: (B)


65. Match the following lists:

List – I                        List – II

a. IC 8051                   i. Stack

b. Nonmaskable          ii. Implied addressing mode

c. PUSH                      iii. TRAP

d. CMA                       iv. Microcontroller

The correct match is

a          b          c          d

(A)       iv         iii         i           ii

(B)       iv         ii          i           iii

(C)       iii         i           ii          iv

(D)       ii          iii         iv         i

Answer: (A)


Answer: (C)


67. Match the following lists:

List – I                                                List – II

a. Envelope detector                           i. TV transmission

b. Foster Seley discriminator              ii. Frequency modulation

c. Varacter diode                                iii. FM detection

d. Vestigial side band                                     iv. AM demodulation

The correct match is given by

a          b          c          d

(A)       iv         iii         ii          i

(B)       i           ii          iii         iv

(C)       ii          iv         iii         i

(D)       i           ii          iv         iii

Answer: (A)


68. Match the following lists:

List – I                        List – II

a. Slip                          i. Relaxation oscillator

b. SCR                        ii. Class-E chopper

c. UJT                          iii. Two-transistor model

d. dc drives                 iv. Induction motors

The correct match is

a          b          c          d

(A)       i           ii          iii         iv

(B)       iii         iv         i           ii

(C)       ii          iii         i           iv

(D)       iv         iii         i           ii

Answer: (D)


69. Match the following lists:

List – I                                                            List – II

a. Intermodal dispersion                                 i. Lasers

b. Chirp                                                           ii. SMF (Single Mode Fiber)

c. Intramodal dispersion                                 iii. III-V group

d. Direct band gap semiconductors                iv. MMF (Multimode Fiber)

The correct match is

a          b          c          d

(A)       iv         i           ii          iii

(B)       iii         iv         i           ii

(C)       ii          i           iii         iv

(D)       i           ii          iii         iv

Answer: (A)


70. Match the following lists:

List – I                                    List – II

a. LVDT                                  i. Speed

b. Techogenerators                  ii. Resistance

c. Wheatstone Bridge                         iii. Displacement

d. Bourdon tube                      iv. Pressure

The correct match is given by

a          b          c          d

(A)       i           ii          iii         iv

(B)       iii         i           ii          iv

(C)       i           iii         ii          iv

(D)       iii         ii          i           iv

Answer: (B)


Read the following paragraph and answer the questions 71 to 75:

Gunn effect is instrumental in the generation of microwave oscillations in bulk semiconductor material. The effect was exhibited by gallium arenide. The effect is a bulk property of semiconductors. If a small dc voltage is placed across a thin slice of germanium arsanide a negative resistance will manifest itself under certain conditions. The voltage gradients across the slice is increase of about 3300 v/cm, oscillations will then occurat microwave frequencies if the slice is connected to a suitably tuned circuit. The Gunn effect is independent of total voltage or current and is not effected by magnetic field, it occurs in n-type of materials only.

The PIN diode consists of a narrow layer of p-type semiconductor separated from an equally narrow layer of n type material. In PIN diode silicon tend to be the main material. The PIN diode is used for microwave power switching, limiting and modulation.


71. The transferred-electron bulk effect occurs in

(A) germanium

(B) gallium arsanide

(C) silicon

(D) metal semiconductor junction

Answer: (B)


72. Indicate which of the following diodes does not use negative resistance in its operation:

(A) Backward

(B) Gunn


(D) Tunnel

Answer: (A)


73. Response time of PIN diode is of the order of

(A) 0.1 ns

(B) 1 ns

(C) 10 ns

(D) 1 milli.sc

Answer: (B)


74. PIN diode is used as

(A) sine wave modulator

(B) triangular wave modulator

(C) square wave modulator

(D) low frequency rectifier

Answer: (D)


75. One of the following microwave diodes is suitable for very low-power oscillator only.

(A) Tunnel

(B) Avalanche

(C) Gunn


Answer: (A)