ELECTRONIC SCIENCE
PAPER – II
Note : This paper contains hundred (100) objective type questions of two (2) marks each. All questions are compulsory.
1. The simple one dimensional diffusion process can be given by :
(1) 
(2) 
(3) 
(4) 
2. In an intrinsic semiconductor, the intrinsic carrier density is :
(1) 
(2) 
(3) 
(4) 
3. The frequency at which the transfer function |H(ω)| of the following RC network is 1/2, will be :
(1) 50 Hz
(2) 200 Hz
(3) 1900 Hz
(4) 1378 Hz
4. The Laplace transform of a signal f(t) is given as ; 
The signal will be :
(1) 2u(t)+3e−t
(2) 3u(t)−2e−t
(3) 3u(t)+2e−t
(4) 2u(t)−3e−t
5. In a circuit shown below, the base current IB is :
(1) 18.58 μA
(2) 19.73 μA
(3) 60.10 μA
(4) 2.63 μA
6. The unity follower circuit is
(1) 
(2) 
(3) 
(4) 
7. The advantage/disadvantage of Schottky TTL logic circuit over Standard TTL logic circuit is that :
(1) It provides low power consumption
(2) It virtually eliminates saturation delay time
(3) It provides simple circuitary
(4) It gives low switching speed
8. 
In a J-K flip-flop we have 
and K=1 (shown in figure). Assuming the flip-flop was initially cleared and clocked for 6 pulses, the sequence at the Q output will be :
(1) 010000
(2) 011001
(3) 010010
(4) 010101
9. In which of the following number systems, AC flag is used in 8085 μp ?
(1) Octal
(2) BCD
(3) Binary
(4) Hexadecimal
10. JMP 2034H in 8085 μp is an example of __________.
(1) 1 byte instruction
(2) 2 byte instruction
(3) 3 byte instruction
(4) None of the above
11. Which of the following is the correct output for the ‘C’ program given below :
(1) XY
(2) YZ
(3) ZW
(4) None of the above
12. Consider the following expression in ‘C’
8+9/3*3−4+9%6 ;
which evaluates to :
(1) 10
(2) 8
(3) 14
(4) 16
13. Which of the following statements in FORTRAN is non-executable statement ?
(1) DO
(2) FORMAT
(3) IF
(4) READ
14. A TRAPATT diode has the following parameters :
Doping concentration=2×1015 cm−3
Current density=20 KA/cm2
The avalanche zone velocity of carriers is given by :
(1) 2.25×105 m/s
(2) 6.25×107 cm/s
(3) 6.25×103 m/s
(4) 2.35×108 m/s
15. The Loading is sometimes used with an antenna in order to increase the :
(1) Bandwidth
(2) Beam width
(3) Effective height
(4) Input capacitance
16. Thermal noise is passed through an ideal low-pass filter having cut-off at fc=ω Hz. The auto-correlation value of the noise at the output of the filter is given as : (1) A delta function at t=0
(2) Gaussian over the range−∞ ≤ t ≤ ∞
(3) Sinc function over the range −∞ ≤ t ≤ ∞
(4) Triangular function over the range 
17. Which of the following statement is correct ?
(1) MF radio frequency waves are called long waves and HF are called short waves.
(2) VLF and LF radio frequency waves are called long waves while HF waves are called short waves.
(3) ELF radio waves are called long waves and HF are called short waves.
(4) LF radio waves are called long waves and VHF are called short waves.
18. A single mode fiber with radius of 4.2 μm, with core-refractive index =1.48 and that of cladding=1.475, the cut-off wavelength is given by :
(1) λc=1334 nm
(2) λc=1525 nm
(3) λc=990 nm
(4) λc=1290 nm
19. A thermostatic cut-out works on the principle of :
(1) Thermal expansion of fluids
(2) Expansion due to air pressure
(3) Variation of resistance with temperature
(4) Thermal expansion of metals
20. If h is the Hydrogen ion concentration in gm/l, the pH value is given as :
(1) log h
(2) −log h
(3) log (1+h)
(4) 
21. In a JFET, the maximum value of transconductance gm is :
(1) 
(2) 
(3) 
(4) 
22. The cut-off frequency of TEM wave is :
(1) Zero
(2) 11.0 GHz
(3) ∞
(4) Moderate
23. Limiter circuit is not needed in the following detector :
(1) Foster – Seeley discriminator
(2) Balanced slope
(3) Ratio detector
(4) None
24. Which of the following is used to analyze all kind of matters ?
(1) Spectrophotometers
(2) Electron Microscope
(3) X-ray diffractometer
(4) Spectrum analyzer
25. In a Silicon oxidation model, if hG is the gas phase mass transfer co-efficient, CG is the oxidant concentration in the bulk of the gas and CS is the oxidant concentration adjacent to the oxide surface, then for steady state, the gas phase flux can be expressed as :
of these statements.
(1) (a) and (c) are correct
(2) (b) is correct but (d) is wrong
(3) (c) is correct but (a) is wrong
(4) (a), (b) and (c) are correct but (d) is wrong
26. When acceptor impurities of concentration NA are added to a semiconductor crystal, when n is the electron density in the conduction band and p is the hole density in the valence band, the ionised acceptors are given as :
of these statements :
(1) (a) and (b) are wrong
(2) (a) is correct but (c) is wrong
(3) (c) is correct but (d) is wrong
(4) (d) is correct but (c) is wrong
27. Which of the following statements are correct for the A/D converters :
(a) The advantage of using a dual slope A/D converter in a digital voltmeter is that its accuracy is high.
(b) The number of comparators in a 4-bit flash A/D converters is 15.
(c) The minimum number of comparators required to built an 8-bit flash A/D converter is 256.
(d) The number of comparators required in a 3-bit comparator type A/D converters is 8.
Options :
(1) (a), (c) and (d) are correct
(2) (b) and (c) are correct
(3) (a) and (b) are correct
(4) (a), (b), (c) and (d) are correct
28. Which of the following statements are correct ?
(a) CMOS has higher speed and smaller power than BJT.
(b) CMOS ICs inputs should never be left unconnected as it may damage the device.
(c) CMOS ICs with Schmitt trigger inputs are useful for better noise immunity.
(d) CMOS is most popular logic family in VLSI Technology.
Options :
(1) (a), (c) and (d) are correct
(2) (b), (c) and (d) are correct
(3) (a), (b) and (c) are correct
(4) (a), (b) and (d) are correct
29. Which of the following statements are correct in respect to 8086 μp ?
(a) The instruction queue size is 8 bytes
(b) Segment register size is 16 bit while physical address size is 20 bits
(c) Segments are disjoint
(d) Beginning address of a segment must be divisible by (16)10
The correct answer is :
(1) (a) and (b) are correct
(2) (b) and (d) are correct
(3) (b) and (c) are correct
(4) (a) and (c) are correct
30. What happens when RET statement is executed in 8085 μp ?
(a) Program counter is cleared
(b) Control is transferred from the subroutine to the main program
(c) Returning address is loaded into the accumulator
(d) Returning address is loaded into the program counter from the top of the stack
The correct answer is :
(1) (a) and (c)
(2) (b) and (d)
(3) (a) and (b)
(4) (b) and (c)
31. If ‘a’ is declared as one-dimensional array in ‘C’ then
(a) *(a+i) is same as *( &a[i] )
(b) *(a+i) is same as *a+i
(c) &a[i] is same as a+i−1
(d) *(a+i) is same as a[i]
Which of the above statements are incorrect ?
(1) (a) and (b)
(2) (a) and (d)
(3) (b) and (c)
(4) (c) and (d)
32. Which of the following specifiers in C++ need not be honored by the compiler ?
(a) static
(b) inline
(c) extern
(d) register
Which of the following is correct ?
(1) (b) and (d)
(2) (a) and (b)
(3) (c) and (d)
(4) (a) and (d)
33. Which of the following statements are true in case of Pulse Code Modulation (PCM) ?
(a) If the number of bits per sample is increased from n to n+1 ; the 
ratio would be 6 dB
(b) The quantization noise depends on sampling rate
(c) The main advantage of PCM is that it possesses better performance in presence of noise
(d) If the number of quantization levels increases from 4 to 64, the bandwidth increase by a factor of 4
Options :
(1) (a) and (b) are correct
(2) (a) and (c) are correct
(3) (a) and (d) are correct
(4) (b) and (c) are correct
34. The following statements are correct for DSB-SC signal :
(a) It is a low pass filter
(b) It needs minimum transmitted power
(c) It is a result of product modulator
(d) Bandwidth of DSB-SC is twice the maximum frequency
Options :
(1) (a), (b) and (c) are correct
(2) (b) and (d) are correct
(3) (a), (b) and (d) are correct
(4) (a), (c) and (d) are correct
35. In an abrupt p-n junction if NA << ND, then the barrier potential is :
of these statements :
(1) (a) is correct but (c) is wrong
(2) (b) is correct but (d) is wrong
(3) (c) is correct but (a) is wrong
(4) (d) is correct but (b) is wrong
36. In a voltage series feedback amplifier with load RL, if Ri is the input resistance without feedback, then the input resistance with feedback is :
of these statements :
(1) (a) and (c) are correct
(2) (b) and (d) are wrong
(3) (a) and (d) are wrong
(4) (c) and (a) are wrong
37. Magnetron is a :
(a) O – type tube
(b) a low power device
(c) a high power device
(d) an oscillator
Out of the above following is correct option :
(1) (a) and (b)
(2) (b) and (d)
(3) (c) and (d)
(4) (a), (c) and (d)
38. A Travelling Wave Tube Amplifier (TWTA) has the following properties :
(a) It provides an octave Bandwidth
(b) It provides an approximate gain of 40dB and more
(c) It has a low noise figure
(d) It has a very high noise figure
Out of the above statements following is correct :
(1) (a), (b) and (d) only
(2) (a) and (d) only
(3) (a) and (b) only
(4) (a) and (b) and (c) only
39. The block diagram of a feedback compensated system is given below :
Which of the following statements are correct ?
(a) When Kt=0, the feedback compensation is in-effective and the system is uncompensated
(b) When Kt=0, the feedback compensation is most effective and system is compensated
(c) The performance of the compensated system depends on Kt and T
(d) The performance of the compensated system does not depend on T
Options :
(1) (a) and (c)
(2) (b) and (c)
(3) (a) and (d)
(4) (b) and (d)
40. The capacitor microphone is most widely used for precision measurements because it has :
(a) Good frequency response
(b) Excellent linearity
(c) Large dynamic pressure range
Which of the above are correct ?
(1) (a) and (b) only
(2) (a) and (c) only
(3) (b) and (c) only
(4) (a), (b) and (c)
41. A good silicon APD has a capacitance of 5pF, with negligible dark current and is operating with a post detection bandwidth of 50 MHz. The photocurrent before gain is given by 10−7 Amp. The operating temperature is 188C . The value of Load resistor to be connected with APD is given by :
(1) 536.5 ohm
(2) 635.5 ohm
(3) 835.5 ohm
(4) 83.5 ohm
42. For optical sources, following statements are given :
(a) They should have large spectral bandwidth
(b) They should have very narrow spectral line width
(c) They should accurately track the electrical input signal
(d) The source should have linearity property
Out of the above, following are correct :
(1) (a), (b), (c) only
(2) (b), (c) and (d) only
(3) (b) and (c) only
(4) (a), (c) and (d) only
43. A multimode graded index fiber, exhibits total pulse broadening of 0.1 μs over a distance of 15 km. Following data is estimated by using the concept of that there is no inter-symbol interference :
(a) The maximum possible Bandwidth is 5 MHz
(b) The dispersion per unit length is 6.67 ns/km
(c) The maximum possible B.W. is 10 MHz
(d) The dispersion/unit length is 3.37 ns/km
Which is the correct option ?
(1) (a) and (d)
(2) (b) and (c)
(3) (c) and (d)
(4) (a) and (b)
44. Consider the following statements regarding z-transform :
(a) The z-transform replaces the Laplace transform for sampled-data system
(b) The z-transform replaces the Laplace transform for continuous-data system
(c) The z-transform provides direct parallels to the s-plane analysis of transients, steady state errors, stability etc.
(d) We cannot map points on s-plane to points on z-plane
Which of the above statements are correct ?
(1) (a) and (c) only
(2) (a) and (d) only
(3) (b), (c) and (d) only
(4) (a), (b) and (d) only
45. Consider the following statements regarding poles and zeros of network function.
(a) The total number of poles is equal to the total number of zeros in a rational network function
(b) The poles and zeros of a network function determine the magnitude of the response
(c) The poles of a network function determine the waveform of the time variation of the response
Which of the above statements are correct ?
(1) (a) and (b) only
(2) (a) and (c) only
(3) (b) and (c) only
(4) (a), (b) and (c)
46. Match the following :
47. Match the following :
48. Match the following :
49. Match the following :
50. Match the following in the context of 8257 programmable DMA controller :
51. Match the following Lists :
52. Match the following Lists if you execute a command-line program “test” in ‘C’ as below :
test string 1 string 2.
53. Match the following Lists in FORTRAN :
54. Match the following Lists :
55. Match the following Lists :
56. Match the following Lists :
57. Match the following Lists :
58. In following lists, there are materials and their band gap energies.
Match the following Lists :
59. Following are the inductances for different Geometries used in Microwaves :
Match the following Lists :
60. Match the following lists in terms of Electrical and Magnetic circuits :
61. Match the following Lists :
62. Match the following Lists :
63. Match the following Lists :
64. Match the following Lists :
65. Match the following Lists :
66. The following semiconductor material are given
(a) C
(b) Si
(c) GaAs
(d) InP
Arrange the above in the increasing order of their Hole Mobility at 300 K.
Options :
(1) (a), (b), (c), (d)
(2) (b), (c), (d), (a)
(3) (c), (d), (a), (b)
(4) (d), (c), (b), (a)
67. Arrange the following amplifier in the increasing order of their Current Gain.
(a) Common-emitter amplifier
(b) Common-base amplifier
(c) Darlington amplifier in common-emitter configuration
(d) Common-collector amplifier
Options :
(1) (b), (a), (d), (c)
(2) (a), (b), (c), (d)
(3) (c), (d), (a), (b)
(4) (d), (c), (b), (a)
68. Arrange the following pins of 8086 μp in the descending order :
The correct sequence is :
(1) (b), (c), (a), (d)
(2) (c), (d), (a), (b)
(3) (d), (b), (c), (a)
(4) (a), (d), (b), (c)
69. What is the correct sequence of the following operators in ‘C’ from highest to lowest precedence order ?
(a) ==
(b) %=
(c) % (d) <=
The correct sequence is :
(1) (c), (b), (a), (d)
(2) (c), (a), (d), (b)
(3) (c), (d), (a), (b)
(4) (a), (b), (d), (c)
70. Following are the semiconductor materials having certain values of recombination co-efficients.
Arrange them in terms of ascending order :
(a) GaP
(b) Si
(c) InAs
(d) GaAs
The correct sequence in ascending order of their values are :
(1) (b), (a), (c), (d)
(2) (d), (b), (a), (c)
(3) (a), (b), (c), (d)
(4) (c), (b), (a), (d)
71. Following transmission media are given :
(a) Twisted pair cables
(b) Optical fiber cables
(c) Coaxial cables
(d) Microwaves
For high rate data transmission systems, arrange the above in terms of their Losses in ascending orders.
The correct sequence is given by :
(1) (b), (c), (a), (d)
(2) (d), (c), (a), (b)
(3) (a), (b), (c), (d)
(4) (b), (d), (c), (a)
72. Consider the following circuits :
(a) Integrating circuit
(b) Active differentiation circuit
(c) Notch type electrical filter
Arrange the above circuit models in decreasing order of their complexity.
(1) (a), (b), (c)
(2) (a), (c), (b)
(3) (b), (c), (a)
(4) (c), (b), (a)
73. Consider the following network :
(a) Power dissipated in resistor R1 is P1
(b) Power dissipated in resistor R2 is P2
(c) Power dissipated in resistor R3 is P3
Arrange the above in increasing order of the dissipated power :
(1) (a), (c), (b)
(2) (a), (b), (c)
(3) (b), (c), (a)
(4) (c), (a), (b)
74. Consider the following systems :
(a) Satellite
(b) Conventional Public Address System
(c) Conventional Radio Receiver
(d) Laser detector
Arrange the above systems in order of their increasing order of operational frequency :
(1) (c), (b), (a), (d)
(2) (b), (c), (d), (a)
(3) (a), (b), (c), (d)
(4) (b), (c), (a), (d)
75. Consider the following logic families :
(a) Standard TTL logic family
(b) ECL – logic family
(c) RTL – logic family
(d) CMOS – logic family
Arrange the above logic families in order of their decreasing power dissipation :
(1) (b), (c), (d) and (a)
(2) (b), (c), (a) and (d)
(3) (c), (b), (a) and (d)
(4) (c), (b), (d) and (a)
Directions : Questions 76 to 95.
The following items consist of two statements, one labelled as “Assertion(A)” and the other labelled as “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.
Code :
(1) Both (A) and (R) are true and (R) is the correct explanation of (A).
(2) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
(3) (A) is true, but (R) is false.
(4) (A) is false, but (R) is true.
76. Assertion (A) : In a p-n junction the electron crossing the junction from right to left constitute a current in the same direction as hole crossing the junction from left to right.
Reason (R) : In a p-n junction the low value of depletion region capacitance can be obtained with reverse biasing.
77. Assertion (A) : For integrated circuit production the line width limit of optical Lithography lies near 0.4 μm, although 0.2 μm feature may eventually be printed under carefully controlled conditions.
Reason (R) : A negative resist on exposure to light becomes less soluble in a developer solution, while a positive resist becomes more soluble.
78. Assertion (A) : The total gain of a cascaded system is determined by the product of the gains of each stage.
Reason (R) : The gain of each stage must be determined under loaded conditions.
79. Assertion (A) : The tunnel diode shows the negative differential resistance between peak voltage and valley voltage.
Reason (R) : In a tunnel diode, for a voltage larger than valley voltage, the current increases exponentially.
80. Assertion (A) : A two byte instruction of 8085 has an operation code in first byte and operand/address in the second byte.
Reason (R) : Source and destination addresses are made implicit in order to reduce the length of an instruction.
81. Assertion (A) : In 8086 μp, ALE is provided by the processor to latch the address into the 8282/8283 address latch.
Reason (R) : Whenever the processor sends a valid address on the multiplexed AD0-AD15 lines, it also makes the ALE high.
82. Assertion (A) : In ‘C’, bit fields cannot be used in a union.
Reason (R) : If one element of union is initialized then it also initializes other elements of the union.
83. Assertion (A) : Encapsulation is implemented by a ‘class’ in C++.
Reason (R) : Private, public and protected access specifiers are used.
84. Assertion (A) : The magnetic flux per unit length through a loop of small length is called the magnetic flux density.
Reason (R) : The direction of magnetic flux density is taken as the normal to the plane of the loop when oriented to enclose maximum flux.
85. Assertion (A) : For transmission lines, having their length equal to odd multiples of 
the following expressions are given sin βL=±1 and cos βL=0.
Reason (R) : Under the above conditions, i.e. for odd multiples of Quarter wavelengths the input impedance becomes equal to 
86. Assertion (A) : The z-parameters are open circuit parameters.
Reason (R) : The z-parameters may be measured at one terminal while the other terminal is open.
87. Assertion (A) : All the mesh currents are necessarily the loop currents but all the loop currents may not be the mesh current.
Reason (R) : The mesh current is the current which flows only around the perimeter of a mesh.
88. Assertion (A) : Vestigial side band gives rise to frequencies very close to the carrier frequency.
Reason (R) : It is not possible to go to extreme and suppress one complete side band by physically realizable filters.
89. Assertion (A) : Lesser number of bits per code are required due to less number of quantization levels in DPCM.
Reason (R) : In this case, the difference between two successive samples is quantized which do not differ much in amplitude.
90. Assertion (A) : The hexadecimal numbers are first converted into binary numbers and operations are performed using binary representation of hexadecimal numbers using rules of binary numbers.
Reason (R) : The information can be handled in hexadecimal form in digital circuits but it is easier to enter information using binary numbers.
91. Assertion (A) : Emitter – Coupled Logic (ECL) is the fastest of all logic families and used in applications where very high speed is essential.
Reason (R) : High speed in ECL is because the transistors are used in difference amplifier configuration in which they are never driven into saturation and the storage time is eliminated.
92. Assertion (A) : The synchronous speed of an induction motor can be varied by varying the frequency of the applied voltage.
Reason (R) : With smaller frequency of operation, there is a large value of slip and motor rotates non-linearly with the frequency ‘f ’ of the applied voltage.
93. Assertion (A) : The diameter of SMF is selected in such a way that single fundamental ray travels straight along the axis of the core of the fiber.
Reason (R) : The diameter of core of SMF is more than 10 μm and outer diameter is less than 125 μm.
94. Assertion (A) : The stability analysis of systems with dead time can be conducted easily using the Bode plots.
Reason (R) : The magnitude plot of a system is unaffected by the presence of dead time.
95. Assertion (A) : A Non-Return to Zero (NRZ) type digital recording system is more common and efficient.
Reason (R) : It is possible to record twice the number of digits for the same number of pulses.
Based on the following para, answer Q.No. 96 to 100.
Sensitivity considerations often are important in the design of Control Systems. Because all physical elements have properties that change with environment and age, we cannot always consider the parameters of the Control System to be completely stationary over the entire operating life of the system. For instance, the winding resistance of an electric motor changes as the temperature of the motor rises during operation. Control systems with electric components may not operate normally when first turned on because of the still-changing system parameters during warmup. This phenomenon is sometimes called “morning sickness”. Most duplicating machines have a warmup period during which time operation is blocked out when first turn on.
96. Which of the following statements is correct ?
(1) A feedback can only increase the sensitivity of a system
(2) A feedback can increase or decrease the sensitivity of a system
(3) A feedback can only decrease the sensitivity of a system
(4) A feedback never affects the sensitivity of a system
97. A good Control System should be :
(a) Very sensitive to parameter variations
(b) Insensitive to parameter variations
(c) Insensitive to input commands
(d) Sensitive to input commands
Which of the above are correct ?
(1) (a) and (b)
(2) (b) and (c)
(3) (b) and (d)
(4) (a) and (d)
98. The open-loop transfer function of a Unity Feedback Control System is given by 
The steady state error will be :
(1) 0.1 rad
(2) 0.2 rad
(3) 0.3 rad
(4) 0.5 rad
99. The sensitivity of the overall (closed-loop) transfer function for the system shown below, with respect to forward path transfer function at ω=1 rad/sec will be :
(1) 0.938
(2) 0.583
(3) 0.25
(4) 0.398
100. For an open-loop control system, sensitivity of overall transfer function M(s) with respect to forward path transfer function G(s) will be :
(1) 1
(2) 0
(3) −1
(4) ∞
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