1. Function corresponding to the Bode plot of the Figure below is

2. A fixed capacitor of reactance –j0.02 ohm is connected in parallel across a series combination of a fixed inductor of reactance j0.01 ohm and a variable resistance R. As resistance R is varied from zero to infinity, the locus diagram of the admittance of this L-C-R circuit will be

(a) A semi-circle of diameter j 100 and center at zero

(b) A semi circle of diameter j50 and center at zero

(c) A straight line inclined at an angle

(d) A straight line parallel to the x-axis

3. The voltage phasor of a circuit is 10∟15º V and the current phasor is 2∟-45º A. The active and the reactive powers in the circuit respectively are.

(a) 10W and 17.32 VAR

(b) 5W and 8.66 VAR

(c) 20W and 60 VAR

(d) 2002 W and 1002 VAR

4. A current of [2√2 sin(314t + 30) + 2√2 cos(952t + 45)] is measured with a thermocouple type 5 Amp full scale, class I meter. The meter reading would lie in the range

a. 5A ± 1%

b. (2 + 3√2)A ± 1%

c. 3A ± 1.7%

d. 2A ± 2.5%

5. A dual-slope analog-to digital converter uses an N-bit counter. When the input signal Va is being integrated, the counter is allowed to count up to a value

(a) equal to 2N – 2

(b) equal to 2N – 1

(c) proportional to Va

(d) inversely proportional to Va

6. A step down chopper operate from a dc voltage source Vs, and feeds a dc motor armature with a back emf Eb. From oscilloscope traces, it is found that the current increases for time tr, falls to zero over time tf, and remains zero for time t0, in every chopping cycle. Then the average dc

voltage across the freewheeling diode is

7. The characteristic equal of a feedback control system is

2

The number of roots in the right half of s-plane are

(a) 0

(b) 1

(c) 2

(d) 3

8. Maximum phase-lead of the compensator

(a) 52 deg at 4 rad/sec

(b) 52 deg at 10 rad/sec

(c) 55 deg at 12 rad/sec

(d) None of these

9. An 8 bit successive approximation analog to digital converter has a full scale reading of 2.55V and its conversion time for an analog input of 1V is 20ms. The conversion time for a 2V input will be

(a) 10ms

(b) 20ms

(c) 40ms

(d) 50ms

10. The amplitude modulated waveform S(t) = A

11. In free space, the time averaged poynting vector in W/m

12. Figure shown below is a mod – K counter. The value of K is

a. 1

b. 2

c. 3

d. 4

13. In the MOSFET amplifier of the figure shown, the signal outputs V

14. In a JK flip-flop, we have K = 1. Assuming the flip-flop was initially cleared and then clocked for 6 pulses, the sequence at the output Q will be

a. 010000

b. 011001

c. 010010

d. 010101

15. The decoding circuit shown in the figure below used to generate the actve low select signal for a microprocessor peripheral. (The address lines are designated as A0 to A7) for IO addresses. The peripheral will correspond to IO address in the range

16. A deterministic signal has the power spectrum given in the figure below.

The minimum sampling rate needed to completely represent this signal is

a. 1KHz

b. 2 KHz

c. 3 KHz

d. None

17. A rectangular air-filled waveguide has cross section of 4 cm X 10 cm. The minimum frequency which can propagate in the waveguide is

a. 1.5 GHz

b. 2.0 GHz

c. 2.5 GHz

d. 3.0 GHz

18. A 1 km long microwave link uses two antennas each having 30 dB gain. If the power transmitted by one antenna is 1 W at 3 GHz, then the power received by the other antenna is approximately

a. 96 µW

b. 76.8 µW

c. 63.4 µW

d. 55.2 µW

19. The following sequence of instruction are executed by an 8085 microprocessor

1000 LXI SP, 27FF

1003 CALL 1006

1006 POP H

The contents of the stack pointer (SP) and the HL register pair on completion of execution of these are

a SP = 27FF, HL = 1003

b. SP = 27FD, HL =1003

c. SP = 27FF, HL =1006

d. SP = 27FD, HL =1006

20. Value of R in the oscillator circuit shown in the figure shown below, is chosen such that the circuit oscillates at an angular frequency of ω.

The value of ω and the required value of R will be respectively

a. 10

b. 2 x 10

c. 2 x 10

d. 10

21. A silicon n-MOSFET has a threshold voltage of 1 volt and oxide thickness of 400 A

a. 1.08 x 10

b. 1.08 x 10

c. 5.4 x 10

d. 5.4 x 10

22. A uniform plane wave in air is normally incident on an infinitely thick slab. If the refractive index of the glass slab is 1.5 then the percentage of the incident power that is reflected from the air-glass interface is

a. 0%

b. 4%

c. 20%

d. 100%

23. A 12 bit ADC is operating with a 1 µsec clock period and the total conversion time is seen to be 14 µsec. The ADC must be of the

a. Flash type

b. Counting type

c. Integrating type

d. Successive Approximation type

24. The output of the circuit shown the figure below is equal to

25. The diffusion potential across a PN junction

a. decreases with increasing doping concentration

b. increases with decreasing band gap

c. does not depend on doping concentration

d. increases with increase in doping concentration

26. The drift velocity of electrons in silicon

a. is proportional to the electric field for all values of electric field

b. Is independent of the electric field

c. Increases at low values of electric field and decreases at high values of electric field exhibiting negative differential resistance

d. Increase linearly with electric field at low values of electric field and gradually saturates at higher values of electric field

27. V(t) = 55[cos(10

(a) DSB suppressed carrier signal

(b) AM signal

(c) SSB upper sideband signal

(d) Narrow band FM signal

28. A small concentration of minority carries is injected into a homogeneous semiconductor crystal at one point. An electric field of 10 V / cm is applied across the crystal and this moves the minority carries a distance of 1 cm is 20 sec. The mobility (in cm2/volt. sec)

a. 1000

b. 2000

c. 5000

d. 500000

29. The 3-dB bandwidth of a typical second-order system with the transfer function given below is

30. In the given circuit, C0 is the distributed capacitance of the coil and C is the tuning capacitor. If C = C1 for the fundamental frequency and C = C2 for the second harmonic, then the value of C0 can be expressed as

31. A digital phase meter is shown in the figure below. If the input signals are VR (t) = VR sinwt and

VP(t) = VP sin (wt +30º), the reading of the meter will be

a. 30

b. 330

c. 150

d. 210

32. In the transistor circuit shown in the figure below, collector-to-ground voltage is +20V. Which of the following is the probable cause of error?

(a) Collector-emitter terminals shorted

(b) Emitter to ground connection open

(c) 10 k ohm resistor open

(d) Collector-base terminals shorted

33. A Lissajous pattern, as shown in the figure below, is observed on the screen of a CRO when voltages of frequencies

a. 3:2

b. 1:2

c. 2:3

d. 2:1

34. In a multicavity magnetron, strapping is employed primarily

(a) To prevent mode jumping

(b) To increase the separation between the resonant frequencies in the π-mode and in the adjacent modes

(c) To reduce the back heating of the cathode

(d) To increase the output of the magnetron

35. The logic realized by the circuit shown in the figure is

36. Figure below shows the circuit of a gate in the Resistor Transistor Logic (RTL) family.

The circuit represents

a. NAND

b. AND

c. NOR

d. OR

37. The initial contents of the 4-bit serial-in-parallel out, right-shift, Shift Register shown in, Figure is

0110.

After three clock pulses are applied, the contents of the Shift Register will be

a. 0000

b. 0101

c. 1010

d. 1111

38. A silicon sample is uniformly doped with 10

(a) n-type with carrier concentration of 10

(b) p-type with carrier concentration of 10

(c) p-type with carrier concentration of 2x10

(d) n-type with carrier concentration of 2x10

39. The open loop transfer function of a feedback control system is G(s)H(s) = 1 / (S + 1)

a. 2

b. 4

c. 8

d. 16

40. A second order system has a transfer function given by G(s) = 25 / (8s

a. π sec

b. π/3 sec

c. 2π/3 sec

d. π/2 sec

41. Two isotropic antennas are separated by a distance of two wavelengths. If both the antennas are fed with currents of equal phase and magnitude, the number of lobes in the radiation pattern in the horizontal plane are

a. 2

b. 4

c. 6

d. 8

42. Which of the following field equations indicate that the magnetic charges do not exist?

43. A 4 GHz carrier is DSB SC modulated by a low pass message signal with maximum frequency of

2MHz. The resultant signal is to be ideally sampled. The minimum frequency of the sampling in train should be

a. 4 MHz

b. 8 MHz

c. 8 GHz

d. 8.004 GHz

44. Zero mean white noise is passed through an ideal low pass filter with cut off at W Hz. The filter output will be uncorrelated at time instants spaced

45. LEDs have response time of the order of

a. 0.1 ns

b. 1 ns

c. 100 ns

d. 1 µs

46. In a uniformly doped abrupt p-n junction, the doping level of the n-side is four times the doping level of the p-side. The ratio of the depletion layer width is

a. 0.25

b. 0.5

c. 1.0

d. 2.0

47. An electromechanical closed-loop control system has the following characteristic equation

S

a. K = 0.528

b. K = 2

c. K = 0

d. K = - 2.528

48. The impulse response and the excitation function of a linear time invariant causal systems are shown in Figures (a) and (b) respectively.

The output of the system at t = 2 sec is equal to

a. 0

b. 0.5

c. 3/2

d. 2

49. The open circuit impedance matrix of the 2-port network shown in the figure is

50. The response of an initially relaxed linear constant parameter network to a unit impulse applied at t = 0 is 4

51. In a twin-wire transmission line in air, the adjacent voltage maxima are at 12.5 cm and 27.5 cm.

The operating frequency is

a. 300 MHz

b. 1 GHz

c. 2 GHz

d. 6.28 GHz

52. Assume that the op-amp of the given Figure is ideal. If 2[1 -

will be

a. Square wave

b. Triangular wave

c. Parabolic wave

d. Sine wave

53. A 75 ohm transmission line is first short terminated and the minima locations are noted. When the short is replaced by a resistive load R

a. 25 Ohm

b. 50 Ohm

c. 225 Ohm

d. 250 Ohm

54. On a resistively terminated high frequency lossless transmission line fed by a 500 MHz source, the VSWR is found to be equal to 2 and the first voltage minimum is measured at 30 cm from the load end. What is the value of the “normalized” load resistance?

a. 3

b. 2

c. 0.5

d. 0.25

55. The slow-wave structure of a TWT is provided with an attenuator. Which one of the following is the function of such an attenuator ?

(a) It prevents of RF power from reaching the output of the device when the beam is switched on

(b) It prevents oscillations in the device

(c) It reduces the noise level of the device

(d) It is used to broadband the device

56. Which one of the following is a transferred electron device?

(a) BARITT diode

(b) IMPATT diode

(c) Gunn diode

(d) Step recovery diode

57. The capacity of an analog communication channel with 4 kHz bandwidth and 15 dB SNR is approximately

(a) 20,000 bps

(b) 16,000 bps

(c) 10,000 bps

(d) 8,000 bps

58. The input pulses to the different stage of the counter shown in the following figure must be of

(a) Constant frequency and constant width

(b) Constant frequency but variable width

(c) Variable frequency but constant width

(d) Variable frequency as well as variable width

59. The circuit shown in the given figure is a

(a) Monostable multivibrator

(b) Frequency division circuit

(c) Miller sweep circuit

(d) Bootstrap sweep circuit

60. Measurement of Hall coefficient in a semiconductor provides information on the

(a) Sign and mass of charge carries

(b) Mass and concentration of charge carriers

(c) Sign of charge carriers alone

(d) Sign and concentration of charge carriers

61. According to a classical free electron theory, the relaxation time and mean free path for aluminium are respectively 0.75x10

a. 1.73 x 10

b. 1.47 x 10

c. 2.62 x 10

d. 4.32 x 10

62. In the graph shown in the Figure, for the tree with branches b, d and f, the fundamental loops would include

1, 2, 3, 4 are nodes

(a) abc, def, bdea

(b) cea, bdea, abc

(c) cdb, def, bfa

(d) adbe, def, cdb

63. In cavity magnetron, strapping is used to

(a) Prevent mode jumping

(b) Prevent cathode back hearting

(c) Ensure bunching

(d) Improve the phase focusing effect

64. An antenna of input resistance 73 ohm is connected to a 50-ohm line. If losses are ignored, then its efficiency will be nearly

(a) 0.19

(b) 0.81

(c) 0.97

(d) 1.19

65. A, B and C are three parallel plates condensers with similar surface area of plates and similar separation. A contains air is dielectric, B contains glass as dielectric and C contains Polythene. If the electric field intensities in air, glass and polythene are respectively E

a. E

b. E

c. E

d. E

66. The circuit diagram of an op-amp based amplifier is shown in the given figure.

The ratio V

a. 9

b. 11

c. 10

d. 21

67. The given figure shows a reflectometer arrangement to measure the parameters of an over coupled one port cavity resonator of f0. With 100 mW of input power, the output power at B is 6.4 mW. What is the value of the coupling coefficient represent?

a. 9

b. 6.4

c. 5

d. 2.5

68. A TE

(a) 15 mm

(b) 10 mm

(c) 9 mm

(d) 7.5 mm

69. In π-mode operation of magnetron, the spokes due to phase focusing effect rotate at an angular velocity corresponding to

(a) One poly/cycle

(b) Two poly/cycle

(c) Four poles/cycle

(d) Six poly/cycle

70. What is the slope change at ω = 10 of the magnitude v/s frequency characteristic of a unity feedback system with the following open-loop transfer function?

71. An amplifier operating over the frequency range of 18 to 20 MHz has a 10kW input resistance.

The RMS noise voltage at the input to the amplifier at ambient temperature of 27

a. 18.2 µV

b. 17.2 µV

c. 16.2 µV

d. 14.2 µV

72. In the root locus for open loop transfer function, G(s) = K(s+6) / (s+3)(s+5) , the break away and break in points are located respectively at

a. – 2 and – 1

b. – 2.47 and – 3.77

c. – 4.27 and – 7.73

d. – 7.73 and – 4.27

73. Under what condition will the instrumentation amplifier circuit given in the Figure possess highest CMRR? ( R

74. A square waveguide carries TE

where the waveguide dimensions are in centimeters. What is the cutoff frequency of the mode?

(a) 5 GHz

(b) 7.5 GHz

(c) 6.5 GHz

(d) 8 GHz

75. Noise temperature (T), and gain (G) are two important parameter of satellite antennas. Which one of the following antennas has the largest G/T ratio?

(a) Parabolic reflector

(b) Cassegranian antenna

(c) Pyramidal horn antenna

(d) Dipole antenna

76. The semiconductor diode which can be used in switching circuits at microwave range is

(a) PIN diode

(b) Varactor diode

(c) Tunnel diode

(d) Gunn diode

77. A conductor having surface density s is embedded in a dielectric medium of permittivity ε. The electric field in the medium is E. If it is known that the pressure p on the conductor surface is equal to the electric energy density in the medium, then p (in SI units) is given by

78. Which one of the following is the Fourier transform of the signal given in Figure (b) if the Fourier

transform of the signal in Figure (a) is given by

79. Microwave antenna aperture efficiency depends on

(a) Feed pattern

(b) Antenna aperture

(c) Surface losses

(d) Low side lobe level

80. A parabolic dish has a diameter of 10m. The maximum possible (ideal) gain of the antenna at λ = 3.14 cm will be

(a) 30 dB

(b) 40 dB

(c) 50 dB

(d) 60 dB

81. The demarcation between Fresnel region and Fraunhofer region fairly approximated by minimum distance between antennas for pattern measurement is (given that R = distance between antennas, D = largest aperture dimension and λ = wavelength)

a. R = λ/D

b. R = λ

c. R = 2D

d. R = 2D

82. A control system is as shown in the given Figure.

The maximum value of gain K for which the system is stable is

a. √3

b. 3

c. 4

d. 5

83. The logic circuit given below converts a binary code Y

(a) Excess-3 code

(b) Gray code

(c) BCD code

(d) Hamming code

84. Which of the following oriented graphs have the same fundamental loop matrix?

Select the correct answer using the codes given below

(a) 1 and 2

(b) 2 and 3

(c) 1, 3 and 4

(d) 2, 3 and 4

85. The Q of a radio coil

(a) Is independent of frequency

(b) Increase monotonically as frequency increases

(c) Decreases monotonically as frequency increases

(d) Increases upto a certain frequency and then decreases beyond that frequency

86. The arrangement shown in the given figure represents an RC potentio meter for measuring and voltage. What should be the value of C so that V

a. 10 µF

b. 11 µF

c. 0.10 µF

d. 0.09 µF

87. In a rectangular cavity resonator having a = width, b = height and d = length. For a > b < d, the dominant mode is

a. TE101

b. TM101

c. TE110

d. TM110

88. Two isotropic antennas are separated by a distance of two wavelengths. If both the antennas are with currents of equal phase and magnitude, the number of lobes in the radiation pattern in the horizontal plane is

a. 2

b. 4

c. 6

d. 8

89. If the vector field

represents a magnetic field, then the value of k must be

a. 1

b. 2

c. – 1

d. – 2

90. An infinite number of concentric rings carry a charge Q each alternately positive and negative.

Their radii are 1, 2, 4, 8 ….. meters in geometric progression as shown. The potential at the center of the will be

91. Two concentric square loops A and B carry equal currents in the same direction. The magnetic field at O due to the two loops A and B will be in the ratio

a. 1:1.414

b. 1:1

c. 1.414:1

d. 2:1

92. In the circuit shown in the Figure below X in an element which always absorbs power. During a particular operation, it sets up a current of 1 amp in the direction shown and absorbs a power P

93. A water boiler at home is switched on to a.c. mains supplying power at 230 V/50 Hz. The frequency of instantaneous power consumed by the boiler is

a. 0 Hz

b. 50 Hz

c. 100 Hz

d. 150 Hz

94. For the system shown in the figure below with a damping ratio ζ of 0.7 and an undamped natural

frequency ω

a. K = 4, a = 0.35

b. K = 8, a = 0.455

c. K = 16, a = 0.225

d. K = 64, a = 0.9

95. Gauss-Seidel iterative method can be used for solving set of

(a) Linear differential equations only

(b) Linear algebraic equations only

(c) Both linear and nonlinear algebraic equation

(d) Both linear and nonlinear differential equations

96. The phase lead compensation is used to

(a) Increase rise time and decrease overshoot

(b) Decrease both rise time and overshoot

(c) Increase both rise time and overshoot

(d) Decrease rise time and increase overshoot

97. Viewed from the terminals A, B the following circuit shown in the Figure below can be reduced to an equivalent circuit of a single voltage source in series with a single resistor with the following parameters

(a) 5 volt source in series with 10 Ω resistor

(b) 7 volt source in series with 2.4 Ω resistor

(c) 15 volt source in series with 2.4 Ω resistor

(d) 1 volt source in series with 10 Ω resistor

98. Figure below shows the input attenuator of a multimeter. The meter reads full scale with 12V at M, with the range switch at position ‘q’. What is the required voltage M to obtain full scale deflection with the range switch a position‘s’?

a. 1 volt

b. 150 volts

c. 120 volts

d. 147 volts

99. Figure below shows the electrostatic vertical deflection system of CRT. Given that V

100. For a flip-flop formed from two NAND gates as shown in the figure below, the unusable state

corresponds to

a. X = 0, Y = 0

b. X = 0, Y = 1

c. X = 1, Y = 0

d. X = 1, Y = 1

2. A fixed capacitor of reactance –j0.02 ohm is connected in parallel across a series combination of a fixed inductor of reactance j0.01 ohm and a variable resistance R. As resistance R is varied from zero to infinity, the locus diagram of the admittance of this L-C-R circuit will be

(a) A semi-circle of diameter j 100 and center at zero

(b) A semi circle of diameter j50 and center at zero

(c) A straight line inclined at an angle

(d) A straight line parallel to the x-axis

3. The voltage phasor of a circuit is 10∟15º V and the current phasor is 2∟-45º A. The active and the reactive powers in the circuit respectively are.

(a) 10W and 17.32 VAR

(b) 5W and 8.66 VAR

(c) 20W and 60 VAR

(d) 2002 W and 1002 VAR

4. A current of [2√2 sin(314t + 30) + 2√2 cos(952t + 45)] is measured with a thermocouple type 5 Amp full scale, class I meter. The meter reading would lie in the range

a. 5A ± 1%

b. (2 + 3√2)A ± 1%

c. 3A ± 1.7%

d. 2A ± 2.5%

5. A dual-slope analog-to digital converter uses an N-bit counter. When the input signal Va is being integrated, the counter is allowed to count up to a value

(a) equal to 2N – 2

(b) equal to 2N – 1

(c) proportional to Va

(d) inversely proportional to Va

6. A step down chopper operate from a dc voltage source Vs, and feeds a dc motor armature with a back emf Eb. From oscilloscope traces, it is found that the current increases for time tr, falls to zero over time tf, and remains zero for time t0, in every chopping cycle. Then the average dc

voltage across the freewheeling diode is

7. The characteristic equal of a feedback control system is

2

*s*^{4}+*s*^{3}+ 3*s*^{2}+ 5*s*+ 10 = 0The number of roots in the right half of s-plane are

(a) 0

(b) 1

(c) 2

(d) 3

8. Maximum phase-lead of the compensator

*D*(s) = (0.5s + 1) / (0.05s + 1)(a) 52 deg at 4 rad/sec

(b) 52 deg at 10 rad/sec

(c) 55 deg at 12 rad/sec

(d) None of these

9. An 8 bit successive approximation analog to digital converter has a full scale reading of 2.55V and its conversion time for an analog input of 1V is 20ms. The conversion time for a 2V input will be

(a) 10ms

(b) 20ms

(c) 40ms

(d) 50ms

10. The amplitude modulated waveform S(t) = A

_{c}[1 + K_{a}m(t)] cosω_{c}t is fed to an ideal envelop detector. The maximum magnitude of K_{a}m(t) is greater than 1. Which of the following could be the detector output?11. In free space, the time averaged poynting vector in W/m

^{2}, for the wave given below is12. Figure shown below is a mod – K counter. The value of K is

b. 2

c. 3

d. 4

13. In the MOSFET amplifier of the figure shown, the signal outputs V

_{1}and V_{2}obey the relationship14. In a JK flip-flop, we have K = 1. Assuming the flip-flop was initially cleared and then clocked for 6 pulses, the sequence at the output Q will be

b. 011001

c. 010010

d. 010101

16. A deterministic signal has the power spectrum given in the figure below.

The minimum sampling rate needed to completely represent this signal is

a. 1KHz

b. 2 KHz

c. 3 KHz

d. None

17. A rectangular air-filled waveguide has cross section of 4 cm X 10 cm. The minimum frequency which can propagate in the waveguide is

a. 1.5 GHz

b. 2.0 GHz

c. 2.5 GHz

d. 3.0 GHz

18. A 1 km long microwave link uses two antennas each having 30 dB gain. If the power transmitted by one antenna is 1 W at 3 GHz, then the power received by the other antenna is approximately

a. 96 µW

b. 76.8 µW

c. 63.4 µW

d. 55.2 µW

19. The following sequence of instruction are executed by an 8085 microprocessor

1000 LXI SP, 27FF

1003 CALL 1006

1006 POP H

The contents of the stack pointer (SP) and the HL register pair on completion of execution of these are

a SP = 27FF, HL = 1003

b. SP = 27FD, HL =1003

c. SP = 27FF, HL =1006

d. SP = 27FD, HL =1006

20. Value of R in the oscillator circuit shown in the figure shown below, is chosen such that the circuit oscillates at an angular frequency of ω.

The value of ω and the required value of R will be respectively

a. 10

^{5}rad/sec, 2 x 10^{4}Ωb. 2 x 10

^{4}rad/sec, 2 x 10^{4}Ωc. 2 x 10

^{4}rad/sec, 10^{5}Ωd. 10

^{5}rad/sec, 10^{5}Ω21. A silicon n-MOSFET has a threshold voltage of 1 volt and oxide thickness of 400 A

^{o}. The region under the gate is ion implanted for threshold voltage tailoring. The dose and type of the implant (assumed to be a sheet charge at the interface) required to shift the threshold voltage to – 1 volt area. 1.08 x 10

^{12}/cm^{2}, p-typeb. 1.08 x 10

^{12}/cm^{2}, n-typec. 5.4 x 10

^{11}/cm^{2}, p-typed. 5.4 x 10

^{11}/cm^{2}, n-type22. A uniform plane wave in air is normally incident on an infinitely thick slab. If the refractive index of the glass slab is 1.5 then the percentage of the incident power that is reflected from the air-glass interface is

a. 0%

b. 4%

c. 20%

d. 100%

23. A 12 bit ADC is operating with a 1 µsec clock period and the total conversion time is seen to be 14 µsec. The ADC must be of the

a. Flash type

b. Counting type

c. Integrating type

d. Successive Approximation type

24. The output of the circuit shown the figure below is equal to

25. The diffusion potential across a PN junction

a. decreases with increasing doping concentration

b. increases with decreasing band gap

c. does not depend on doping concentration

d. increases with increase in doping concentration

26. The drift velocity of electrons in silicon

a. is proportional to the electric field for all values of electric field

b. Is independent of the electric field

c. Increases at low values of electric field and decreases at high values of electric field exhibiting negative differential resistance

d. Increase linearly with electric field at low values of electric field and gradually saturates at higher values of electric field

27. V(t) = 55[cos(10

^{6}ωt – sin(10^{3}ωt) x sin(10^{6}ωt))] represents(a) DSB suppressed carrier signal

(b) AM signal

(c) SSB upper sideband signal

(d) Narrow band FM signal

28. A small concentration of minority carries is injected into a homogeneous semiconductor crystal at one point. An electric field of 10 V / cm is applied across the crystal and this moves the minority carries a distance of 1 cm is 20 sec. The mobility (in cm2/volt. sec)

a. 1000

b. 2000

c. 5000

d. 500000

29. The 3-dB bandwidth of a typical second-order system with the transfer function given below is

30. In the given circuit, C0 is the distributed capacitance of the coil and C is the tuning capacitor. If C = C1 for the fundamental frequency and C = C2 for the second harmonic, then the value of C0 can be expressed as

31. A digital phase meter is shown in the figure below. If the input signals are VR (t) = VR sinwt and

VP(t) = VP sin (wt +30º), the reading of the meter will be

a. 30

^{o}b. 330

^{o}c. 150

^{o}d. 210

^{o}32. In the transistor circuit shown in the figure below, collector-to-ground voltage is +20V. Which of the following is the probable cause of error?

(a) Collector-emitter terminals shorted

(b) Emitter to ground connection open

(c) 10 k ohm resistor open

(d) Collector-base terminals shorted

33. A Lissajous pattern, as shown in the figure below, is observed on the screen of a CRO when voltages of frequencies

*fx*and*fy*are applied to the x and y plates respectively.*fx*:*fy*is then equal toa. 3:2

b. 1:2

c. 2:3

d. 2:1

34. In a multicavity magnetron, strapping is employed primarily

(a) To prevent mode jumping

(b) To increase the separation between the resonant frequencies in the π-mode and in the adjacent modes

(c) To reduce the back heating of the cathode

(d) To increase the output of the magnetron

35. The logic realized by the circuit shown in the figure is

36. Figure below shows the circuit of a gate in the Resistor Transistor Logic (RTL) family.

The circuit represents

a. NAND

b. AND

c. NOR

d. OR

37. The initial contents of the 4-bit serial-in-parallel out, right-shift, Shift Register shown in, Figure is

0110.

After three clock pulses are applied, the contents of the Shift Register will be

a. 0000

b. 0101

c. 1010

d. 1111

38. A silicon sample is uniformly doped with 10

^{16}phosphorus atoms/cm3 and 2x10^{16}boron atoms/cm_{3}. If all the dopants are full ionized, the material is(a) n-type with carrier concentration of 10

^{16}/cm3(b) p-type with carrier concentration of 10

^{16}/cm3(c) p-type with carrier concentration of 2x10

^{16}/cm3(d) n-type with carrier concentration of 2x10

^{16}/cm339. The open loop transfer function of a feedback control system is G(s)H(s) = 1 / (S + 1)

^{3}. The gain margin of the system isa. 2

b. 4

c. 8

d. 16

40. A second order system has a transfer function given by G(s) = 25 / (8s

^{2}+ 8s +25). If the system initially at rest is subjected to a unit step input at t=0, the second peak in the response will occur ata. π sec

b. π/3 sec

c. 2π/3 sec

d. π/2 sec

41. Two isotropic antennas are separated by a distance of two wavelengths. If both the antennas are fed with currents of equal phase and magnitude, the number of lobes in the radiation pattern in the horizontal plane are

a. 2

b. 4

c. 6

d. 8

42. Which of the following field equations indicate that the magnetic charges do not exist?

43. A 4 GHz carrier is DSB SC modulated by a low pass message signal with maximum frequency of

2MHz. The resultant signal is to be ideally sampled. The minimum frequency of the sampling in train should be

a. 4 MHz

b. 8 MHz

c. 8 GHz

d. 8.004 GHz

44. Zero mean white noise is passed through an ideal low pass filter with cut off at W Hz. The filter output will be uncorrelated at time instants spaced

45. LEDs have response time of the order of

a. 0.1 ns

b. 1 ns

c. 100 ns

d. 1 µs

46. In a uniformly doped abrupt p-n junction, the doping level of the n-side is four times the doping level of the p-side. The ratio of the depletion layer width is

a. 0.25

b. 0.5

c. 1.0

d. 2.0

47. An electromechanical closed-loop control system has the following characteristic equation

S

^{3}+ 6KS^{2}+ (K + 2)S + 8 = 0, Where K is the forward gain of the system. The condition for closed loop stability isa. K = 0.528

b. K = 2

c. K = 0

d. K = - 2.528

48. The impulse response and the excitation function of a linear time invariant causal systems are shown in Figures (a) and (b) respectively.

The output of the system at t = 2 sec is equal to

a. 0

b. 0.5

c. 3/2

d. 2

49. The open circuit impedance matrix of the 2-port network shown in the figure is

50. The response of an initially relaxed linear constant parameter network to a unit impulse applied at t = 0 is 4

*e*^{-2t}*u*(*t*). The response of this network to a unit step function will be51. In a twin-wire transmission line in air, the adjacent voltage maxima are at 12.5 cm and 27.5 cm.

The operating frequency is

a. 300 MHz

b. 1 GHz

c. 2 GHz

d. 6.28 GHz

52. Assume that the op-amp of the given Figure is ideal. If 2[1 -

*e*is a triangular wave, then^{2t}]u(t)*v0*will be

a. Square wave

b. Triangular wave

c. Parabolic wave

d. Sine wave

53. A 75 ohm transmission line is first short terminated and the minima locations are noted. When the short is replaced by a resistive load R

_{L}, the minima locations are not altered and VSWR is measured to be 3. What is the value of R_{L}?a. 25 Ohm

b. 50 Ohm

c. 225 Ohm

d. 250 Ohm

54. On a resistively terminated high frequency lossless transmission line fed by a 500 MHz source, the VSWR is found to be equal to 2 and the first voltage minimum is measured at 30 cm from the load end. What is the value of the “normalized” load resistance?

a. 3

b. 2

c. 0.5

d. 0.25

55. The slow-wave structure of a TWT is provided with an attenuator. Which one of the following is the function of such an attenuator ?

(a) It prevents of RF power from reaching the output of the device when the beam is switched on

(b) It prevents oscillations in the device

(c) It reduces the noise level of the device

(d) It is used to broadband the device

56. Which one of the following is a transferred electron device?

(a) BARITT diode

(b) IMPATT diode

(c) Gunn diode

(d) Step recovery diode

57. The capacity of an analog communication channel with 4 kHz bandwidth and 15 dB SNR is approximately

(a) 20,000 bps

(b) 16,000 bps

(c) 10,000 bps

(d) 8,000 bps

58. The input pulses to the different stage of the counter shown in the following figure must be of

(a) Constant frequency and constant width

(b) Constant frequency but variable width

(c) Variable frequency but constant width

(d) Variable frequency as well as variable width

59. The circuit shown in the given figure is a

(a) Monostable multivibrator

(b) Frequency division circuit

(c) Miller sweep circuit

(d) Bootstrap sweep circuit

60. Measurement of Hall coefficient in a semiconductor provides information on the

(a) Sign and mass of charge carries

(b) Mass and concentration of charge carriers

(c) Sign of charge carriers alone

(d) Sign and concentration of charge carriers

61. According to a classical free electron theory, the relaxation time and mean free path for aluminium are respectively 0.75x10

^{–14}s and 0.88 mm. Given that the density of aluminium is 2700 kg/m^{3}and the atomic weight of aluminium is 26.98, the resistivity of aluminium isa. 1.73 x 10

^{-8}Ω-mb. 1.47 x 10

^{-8}Ω-mc. 2.62 x 10

^{-8}Ω-md. 4.32 x 10

^{-8}Ω-m62. In the graph shown in the Figure, for the tree with branches b, d and f, the fundamental loops would include

1, 2, 3, 4 are nodes

*a, b, c, d, e f*are branches(a) abc, def, bdea

(b) cea, bdea, abc

(c) cdb, def, bfa

(d) adbe, def, cdb

63. In cavity magnetron, strapping is used to

(a) Prevent mode jumping

(b) Prevent cathode back hearting

(c) Ensure bunching

(d) Improve the phase focusing effect

64. An antenna of input resistance 73 ohm is connected to a 50-ohm line. If losses are ignored, then its efficiency will be nearly

(a) 0.19

(b) 0.81

(c) 0.97

(d) 1.19

65. A, B and C are three parallel plates condensers with similar surface area of plates and similar separation. A contains air is dielectric, B contains glass as dielectric and C contains Polythene. If the electric field intensities in air, glass and polythene are respectively E

_{1}, E_{2}and E_{3}then (assume that the plates are filled with the given dielectrics)a. E

_{1}= E_{2}= E_{3}b. E

_{1}= E_{2}> E_{3}c. E

_{1}> E_{2}> E_{3}d. E

_{1}< E_{2}> E_{3}66. The circuit diagram of an op-amp based amplifier is shown in the given figure.

_{}The ratio V

_{out}/V_{in }is equal toa. 9

b. 11

c. 10

d. 21

67. The given figure shows a reflectometer arrangement to measure the parameters of an over coupled one port cavity resonator of f0. With 100 mW of input power, the output power at B is 6.4 mW. What is the value of the coupling coefficient represent?

a. 9

b. 6.4

c. 5

d. 2.5

68. A TE

_{10}rectangular waveguide is to be designed for operation over 25-35 GHz and the band center is 1.5 times the cutoff frequency. What should be the dimension of the broad side?(a) 15 mm

(b) 10 mm

(c) 9 mm

(d) 7.5 mm

69. In π-mode operation of magnetron, the spokes due to phase focusing effect rotate at an angular velocity corresponding to

(a) One poly/cycle

(b) Two poly/cycle

(c) Four poles/cycle

(d) Six poly/cycle

70. What is the slope change at ω = 10 of the magnitude v/s frequency characteristic of a unity feedback system with the following open-loop transfer function?

71. An amplifier operating over the frequency range of 18 to 20 MHz has a 10kW input resistance.

The RMS noise voltage at the input to the amplifier at ambient temperature of 27

^{o}C is (Assume the Boltzman constant value as 1.38x10^{–23}J/K)a. 18.2 µV

b. 17.2 µV

c. 16.2 µV

d. 14.2 µV

72. In the root locus for open loop transfer function, G(s) = K(s+6) / (s+3)(s+5) , the break away and break in points are located respectively at

a. – 2 and – 1

b. – 2.47 and – 3.77

c. – 4.27 and – 7.73

d. – 7.73 and – 4.27

73. Under what condition will the instrumentation amplifier circuit given in the Figure possess highest CMRR? ( R

_{s1}and R_{s2}are source resistances)74. A square waveguide carries TE

_{11}mode whose axial magnetic field is given bywhere the waveguide dimensions are in centimeters. What is the cutoff frequency of the mode?

(a) 5 GHz

(b) 7.5 GHz

(c) 6.5 GHz

(d) 8 GHz

75. Noise temperature (T), and gain (G) are two important parameter of satellite antennas. Which one of the following antennas has the largest G/T ratio?

(a) Parabolic reflector

(b) Cassegranian antenna

(c) Pyramidal horn antenna

(d) Dipole antenna

76. The semiconductor diode which can be used in switching circuits at microwave range is

(a) PIN diode

(b) Varactor diode

(c) Tunnel diode

(d) Gunn diode

77. A conductor having surface density s is embedded in a dielectric medium of permittivity ε. The electric field in the medium is E. If it is known that the pressure p on the conductor surface is equal to the electric energy density in the medium, then p (in SI units) is given by

78. Which one of the following is the Fourier transform of the signal given in Figure (b) if the Fourier

transform of the signal in Figure (a) is given by

79. Microwave antenna aperture efficiency depends on

(a) Feed pattern

(b) Antenna aperture

(c) Surface losses

(d) Low side lobe level

80. A parabolic dish has a diameter of 10m. The maximum possible (ideal) gain of the antenna at λ = 3.14 cm will be

(a) 30 dB

(b) 40 dB

(c) 50 dB

(d) 60 dB

81. The demarcation between Fresnel region and Fraunhofer region fairly approximated by minimum distance between antennas for pattern measurement is (given that R = distance between antennas, D = largest aperture dimension and λ = wavelength)

a. R = λ/D

^{2}b. R = λ

^{2}/2D^{2}c. R = 2D

^{2}/λd. R = 2D

^{2}/λ^{2}82. A control system is as shown in the given Figure.

The maximum value of gain K for which the system is stable is

a. √3

b. 3

c. 4

d. 5

83. The logic circuit given below converts a binary code Y

_{1}Y_{2}Y_{3}into(a) Excess-3 code

(b) Gray code

(c) BCD code

(d) Hamming code

84. Which of the following oriented graphs have the same fundamental loop matrix?

Select the correct answer using the codes given below

(a) 1 and 2

(b) 2 and 3

(c) 1, 3 and 4

(d) 2, 3 and 4

85. The Q of a radio coil

(a) Is independent of frequency

(b) Increase monotonically as frequency increases

(c) Decreases monotonically as frequency increases

(d) Increases upto a certain frequency and then decreases beyond that frequency

86. The arrangement shown in the given figure represents an RC potentio meter for measuring and voltage. What should be the value of C so that V

_{o}/V_{in}is independent of the frequency of the input signal?a. 10 µF

b. 11 µF

c. 0.10 µF

d. 0.09 µF

87. In a rectangular cavity resonator having a = width, b = height and d = length. For a > b < d, the dominant mode is

a. TE101

b. TM101

c. TE110

d. TM110

88. Two isotropic antennas are separated by a distance of two wavelengths. If both the antennas are with currents of equal phase and magnitude, the number of lobes in the radiation pattern in the horizontal plane is

a. 2

b. 4

c. 6

d. 8

89. If the vector field

represents a magnetic field, then the value of k must be

a. 1

b. 2

c. – 1

d. – 2

90. An infinite number of concentric rings carry a charge Q each alternately positive and negative.

Their radii are 1, 2, 4, 8 ….. meters in geometric progression as shown. The potential at the center of the will be

91. Two concentric square loops A and B carry equal currents in the same direction. The magnetic field at O due to the two loops A and B will be in the ratio

a. 1:1.414

b. 1:1

c. 1.414:1

d. 2:1

92. In the circuit shown in the Figure below X in an element which always absorbs power. During a particular operation, it sets up a current of 1 amp in the direction shown and absorbs a power P

_{x}. It is possible that X can absorb the same P_{x }for another current I, the value of this current is93. A water boiler at home is switched on to a.c. mains supplying power at 230 V/50 Hz. The frequency of instantaneous power consumed by the boiler is

a. 0 Hz

b. 50 Hz

c. 100 Hz

d. 150 Hz

94. For the system shown in the figure below with a damping ratio ζ of 0.7 and an undamped natural

frequency ω

_{n}of 4 rad/sec, the values of K and a area. K = 4, a = 0.35

b. K = 8, a = 0.455

c. K = 16, a = 0.225

d. K = 64, a = 0.9

95. Gauss-Seidel iterative method can be used for solving set of

(a) Linear differential equations only

(b) Linear algebraic equations only

(c) Both linear and nonlinear algebraic equation

(d) Both linear and nonlinear differential equations

96. The phase lead compensation is used to

(a) Increase rise time and decrease overshoot

(b) Decrease both rise time and overshoot

(c) Increase both rise time and overshoot

(d) Decrease rise time and increase overshoot

97. Viewed from the terminals A, B the following circuit shown in the Figure below can be reduced to an equivalent circuit of a single voltage source in series with a single resistor with the following parameters

(a) 5 volt source in series with 10 Ω resistor

(b) 7 volt source in series with 2.4 Ω resistor

(c) 15 volt source in series with 2.4 Ω resistor

(d) 1 volt source in series with 10 Ω resistor

98. Figure below shows the input attenuator of a multimeter. The meter reads full scale with 12V at M, with the range switch at position ‘q’. What is the required voltage M to obtain full scale deflection with the range switch a position‘s’?

a. 1 volt

b. 150 volts

c. 120 volts

d. 147 volts

99. Figure below shows the electrostatic vertical deflection system of CRT. Given that V

_{A}is the accelerating voltage, the deflection sensitivity (deflection/volt) is proportional to100. For a flip-flop formed from two NAND gates as shown in the figure below, the unusable state

corresponds to

a. X = 0, Y = 0

b. X = 0, Y = 1

c. X = 1, Y = 0

d. X = 1, Y = 1