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1. Divergence of the three dimensional radial vector field is A. 3 B. C. D. 2. If ( x, y, z ) is a scalar function, then is A. B. C. D. 1 0 3 -3 t 3. If F (s) is the Laplace transform of f (t ) , then the Laplace transform of f ( )d is 0 equal to 1 s F (s) s 1 B. F ( s ) s C. sF (s) D. F (s)ds A. 4 2 , one of its eigen vectors is 3 4. Given a matrix 4 1 A. 2 3 B. 2 2 C. 1 4 D. 3 3 5. If x and y satisfy the implicit function f ( x, y ) x y y x 0 , then dy is given by dx y ln y A. x x ln x y x ln y y B. y ln x x C. x y 2 y x2 y x ln y D. x y ln x 6. The Newton Raphson method formula for finding the square root of a real number R from the equation x 2 R 0 is xi 2 3 xi B. xi 1 2 1 R C. xi 1 3xi 2 xi 1 R D. xi 1 xi 2 xi A. x i 1 7. Determinant of a 5 × 5 orthogonal matrix can take values A. B. C. D. 0 1 25 5 8. The signal x(t ) is described by x(t ) 1 for 1 t 1, and x(t) 0 otherwise. The two angular frequencies at which its Fourier transform becomes zero are A. B. C. D. 0.5 , 1.5 0 , , 2 0.5 , 2.5 4 9. Which of the options correspond to derivative of the symmetric function shown below A. B. C. D. 10. The Laplace Transform of the function shown in the figure (sum of two delta functions) is given by f(t) A. B. C. D. 2 j cos s 2 j sin s Zero 2 coss 11. The value of integral -1 is A. B. C. D. 5 1 t 12. If Laplace transform of is then Laplace transform of is A. B. C. D. 13. If f(x) is a symmetric periodic function of x, then the Fourier series of the function f(x) will be of the form A. B. C. D. 2 14. If r xiˆ yjˆ zkˆ , then grad (e r ) has the value 2 A. 2rrer 2 B. 2 re r 1 r2 C. re 2 2 D. re r d2y dy 5 6 y e x is: 15. The complete solution of the differential equation 2 dx dx x e A. y c1e x c2 e 2 x 2 ex B. y c1e2 x c2e3 x 2 1 2 x ex C. y c1e c2e3 x 2 2 x e D. y (c1 c2 x)e 2 x 2 6 16. The value of the contour integral C A. B. C. D. z3 z 2 2 , C is the unit circle (counterclockwise) is 24πi 0 12πi 6πi 17. The Laplace transform of f (t ) A. 3 B. 3 C. 3 is t s 3 3 D. 3 s 18. The intensity pattern shown in the figure is the diffraction pattern for a N-slit array with slit width b and slit seperation a . The values of N and A. B. C. D. a are b 2 and 3 3 and 2 4 and 3 5 and 2 19. In the design of a single mode step index optical fiber close to upper cut off , the single mode operation is NOT preserved if A. B. C. D. radius as well as operating wavelength are halved radius as well as operating wavelength are doubled radius is doubled and operating wavelength is halved radius is halved and operating wavelength is doubled 20. The work function of silver and sodium are 4.6 eV and 2.3 eV respectively. The ratio of the slope of the stopping potential versus frequency plot for silver and sodium in a photoelectric effect experiment is A. 1 2 B. 2 C. 1 D. 2 7 21. The refractive index of glass is 1.5. The wavelength of light with frequency 1014 Hz in glass is A. B. C. D. 2 m 3 m 4.5 m 1 m 22. The wave function of a quantum mechanical particle is given by 3 5 4 5 ( x) 1 ( x) 2 ( x) where 1 ( x) and 2 ( x) are eigenfunctions with eigenvalues -1 eV and -2 eV respectively. The energy of the particle in the state (x) is 11 5 41 B. 25 36 C. 25 7 D. 5 A. 23. Unpolarized light of intensity I0 is incident on two ideal linear polarizers whose transmission axes differ by 60 degrees. The intensity of the transmitted light is I0 4 I0 B. 2 I C. 0 8 3I 0 D. 4 A. 24. X rays are A. B. C. D. Cathode rays and are made of electrons Positive rays and made of positrons. Neutral and made of photons. Neutral and made of neutrons. 8 25. If λo is the de Broglie wavelength for a proton accelerated through a potential V, then the de Broglie wavelength for an α particle accelerated through the same potential is A. o / 2 2 B. 2 2o C. o / 2 D. o / 2 26. In C language, which of the following special symbols is allowed in a variable name? A. B. C. D. * (asterisk) _ (underscore) | (pipeline) – (hyphen) 27. In the C program given below, point out the error, if any, in the for loop main() { int i=1; for (;;) { printf(“%d”, i++); if(i>10) break; } } A. B. C. D. The condition in the for loop is a must. The two semicolons should be dropped. The for loop should be replaced by a while loop. No error. 28. In C language, which function is used to round off a value from 1.66 to 2.0? A. B. C. D. floor(1.66) roundup(1.66) ceil(1.66) rountdto(1.66) 9 29. What would be the output of the following C program, if the array begins at address 1200? main() { int arr[ ] = {2,3,4,1,6}; printf(“%d%d”, arr, sizeof(arr)); } A. B. C. D. 1201 1200 1201 1200 5 1024 1024 10 30. If the sequence of operation – push (1), push (2), pop, push (1), push (2), pop, pop, pop, push (2), pop are performed on a stack, the sequence of the popped out values are A. B. C. D. 2 2 2 2 2 1 2 1 1 1 1 2 2 2 1 2 2 2 2 2 31. Which of the following is a PNPN device and has two common gates ? A. B. C. D. DIAC SCR BJT TRIAC 32. A n-type semiconductor has Hall coefficient of 150 cm3/C and resistivity ρ = 0.05 Ω cm. The electron mobility will be A. B. C. D. 3000 cm2/V-s 2560 cm2/V-s 25.60 cm2/V-s 2000 cm2/V-s 33. When temperature is increased from room temperature the resistivity of an intrinsic semiconductor A. B. C. D. decreases increases becomes zero does not change 10 34. The diamond crystal structure is formed by A. B. C. D. two interlaced bcc unit cells three interlaced fcc unit cells three interlaced bcc unit cells two interlaced fcc unit cells 35. The longest wavelength that can be used to analyze the NaCl crystal planes of spacing d = 2.82 Å in the first order is A. B. C. D. 1.45 × 10-10 m 2.82 × 10-10 m 5.64 × 10-10 m 4.64 × 10-10 m 36. If the Fermi energy is 3kT above the edge of the conduction band, then the probability of finding an electron at the Fermi energy EF is A. B. C. D. 1.0 0.3 0.7 0.5 37. The density of impurity atoms that must be added to intrinsic silicon to convert it to 10-1Ω m p-type silicon with hole mobility 0.05 m2/V is A. B. C. D. 1.25 × 1017 /m3 1.25 × 1021 /m3 1.25 × 1021 /cm3 1.25 × 1017 /cm3 38. In case of intrinsic semiconductors the Fermi level EF lies exactly in the center of the forbidden energy gap Eg when A. B. C. D. the effective mass of a hole is equal to the effective mass of the free electron the effective mass of a hole is less than the effective mass of the free electron the effective mass of a hole is greater than the effective mass of the free electron the charge of a hole is equal to charge of an electron 39. In a typical Hall effect experiment, if a 1.6 mm thick sample of n-type germanium with donor density 1021/m3 is placed in a magnetic field of 5 weber/m2, the Hall voltage developed for a current density of 500 A/m2 is A. B. C. D. 40 mV 35 mV 10 mV 25 mV 11 40. When a p-n junction diode is forward biased A. B. C. D. the depletion region is reduced and barrier height is increased both the depletion region and barrier height are reduced the depletion region is increased and barrier height is reduced both the depletion region and barrier height are increased 41. In a p-n junction, the depletion layer consists of A. B. C. D. immobile ions protons electrons mobile ions 42. An ideal diode should have A. B. C. D. zero resistance in forward bias as well as reverse bias zero resistance in forward bias and an infinitely large resistance in reverse bias infinitely large resistance in reverse bias infinitely large resistance in forward as well as reverse bias 43. The minimum gate current which can turn an SCR on is called A. B. C. D. holding current trigger current junction current break over current 44. A UnijunctionTransistor (UJT) has A. B. C. D. one emitter and two bases two emitters and one base one emitter and one base two emitters and two bases 45. What are the bias conditions of the emitter-base and collector-base junctions respectively for a BJT to operate as an amplifier? A. B. C. D. Reverse; Forward Reverse; Reverse Forward; Reverse Forward; Forward 12 46. To make a good non-rectifying contact between a metal and n-type semiconductor, A. the semiconductor should be lightly doped B. the work function of metal should be greater than the work function of semiconductor C. the work function of metal should be lower than the work function of semiconductor D. the metal should have a high Schottky barrier height 47. For an ideal JFET, when VDS is increased beyond the pinch off point, the drain current A. B. C. D. remains constant increases decreases first decreases and then increases 48. If the forward current–voltage characteristic of a p-n junction diode has a slope of 50 mA/V at a desired point then the approximate incremental resistance of the diode is A. B. C. D. 20 Ω 50 Ω 10 Ω 35 Ω 49. In an n-channel enhancement MOSFET, at a fixed drain voltage A. the drain current has a finite value at zero gate voltage and it increases with applied negative gate voltage. B. the drain current is zero at zero gate voltage and it increases with the applied positive gate voltage. C. the drain current is maximum at zero gate voltage and it decreases with applied negative gate voltage. D. the drain current is maximum at zero gate voltage and it decreases with positive gate voltage. 50. If a transistor has 0.97 then the value of β is A. B. C. D. 32.33 0 1 2.94 13 51. Consider the following statements associated with reciprocal two port networks: 1. Z12 = Z21 2. Y12 = Y21 3. h12 = h21 4. AD-BC =1 Which of the statements given above are correct ? A. B. C. D. 1,2,3 1,2,4 1,3,4 2,3,4 52. In an RLC circuit v(t ) 20 sin(314t 5 2 ) and i(t ) 10 sin(314t ) . The power 6 3 factor of the circuit is A. B. C. D. 0.5 0.707 1.0 0.866 53. The value of R in the circuit when the current is zero in the branch AB is A. B. C. D. 10Ω 60 Ω 20 Ω 40 Ω 30 Ω A 12 V 20Ω B 10Ω 10Ω 5Ω 54. If each branch of a delta circuit has an impedance equivalent Y circuit has an impedance A. 5Ω R 3 Z , then each branch of the Z 3 B. 3Z C. 3 3Z Z D. 3 55. The current through RL for the network shown in the figure is A. B. C. D. 6A 3A 4A 9A 8Ω I2 32V 14 6A 24Ω RL 14Ω 56. The inductance of a coil in which the current increases linearly from 0 to 0.2 A in a time interval of 0.3 sec producing a voltage of 10 V is A. B. C. D. 9H 10 H 15 H 1.5 H 57. The differential equation for the current in the circuit of the figure shown is A. B. C. D. d 2i di 2 2 2 i(t ) sin(t ) dt dt 2 d i di 2 2i(t ) cos(t ) 2 dt dt 2 d i di 2 2 2 i (t ) cos(t ) dt dt 2 d i di 2 2i (t ) sin(t ) 2 dt dt 2Ω sin t ͠ 2H 1F 58. An inductor of 5 mH will have the same reactance as a capacitor of 0.1 μF at an approximate frequency of A. B. C. D. 10 kHz 14 kHz 7 kHz 0.7 kHz 59. A coil having R = 120 Ω and L = 24 H is connected across a 12 V battery. The time constant and the current after 0.2 second is A. B. C. D. 5 sec, 100 mA 0.5 sec, 63 mA 0.2 sec, 63 mA 0.2 sec, 100 mA 60. While drawing the Thevenin circuit, Vth equals the A. B. C. D. short circuit terminal voltage net voltage available in the circuit EMF of battery nearest to these terminals open circuit terminal voltage 15 61. In the circuit shown in the figure, the value of load resistance RL which would extract maximum power from the circuit is 3Ω 4Ω A. B. C. D. 6.0 Ω 5.4 Ω 36V 6.5 Ω 6Ω RL 8.0 Ω 62. A certain current source has the values IS = 4 µA and RS = 1.2 MΩ. The values for an equivalent voltage source are A. B. C. D. 4.8 V, 1.2 MΩ 4.8 V, 4.8 MΩ 1 V, 1.2 MΩ 4.8 µV, 1.2 MΩ 63. Find the current through the resistance R2 for the circuit shown in the figure. A. B. C. D. 0A 1.5 A 2.5 A 5A 64. A 12 V source has an internal resistance of 90 Ω. If a load resistance of 10 Ω is connected to the voltage source, the load power is A. B. C. D. 188 mW 0W 44 W 144 mW 65. A capacitor is charged by a constant current of 2 mA and results in a voltage increase of 12 V in a 10 sec interval. The value of capacitance is A. B. C. D. 0.75 mF 1.33 mF 0.6 mF 1.67 mF 66. In a transistor a change of 8.0 mA in the emitter current produces a change of 7.8 mA in the collector current. What change in the base current is necessary to produce the same change in the collector current? A. B. C. D. 200 µA 150 µA 50 µA 100 µA 16 67. Resonance frequency of a parallel LC resonance circuit is 1 Hz LC 1 B. Hz 2 LC A. C. D. LC Hz 2 Hz LC 68. A chopper has a supply voltage of 200 V dc, ON time of 30 ms and OFF time of 10 ms. The duty cycle and average dc output voltage are A. B. C. D. 0.50 and 0.50 and 0.75 and 0.75 and 100V 150V 150V 100V 69. A negative feedback amplifier has an internal gain A=100 and feedback factor =0.1. Its gain with feedback will be A. B. C. D. 0.11 9.09 11.1 109.9 70. An ideal current source is one whose internal resistance is A. B. C. D. zero very high very low Infinite 71. The figure shown below represents an op amp circuit. If R1 = infinity and R2 = 0, then the circuit is A. B. C. D. an inverting amplifier with ideal gain infinity an inverting amplifier with Vo = 0 a non inverting amplifier with Vo = Vin a non inverting amplifier with ideal gain infinity 17 72. A square wave input of 8V peak-to-peak magnitude and frequency 2 MHz is applied to a voltage follower, which produces the triangular output as shown in the figure. What is its slew rate? V0 A. B. C. D. +2V 16 V/µs 8 V/µs 4 V/µs 2 V/µs t -2V 0.5 µs 0.5 µs 73. A non-inverting op amp circuit shown in the figure has a series resistor R1 = 10 k and a voltage gain of 20 dB. The value of the feedback resistor R2 is A. B. C. D. 90 k 76 k 10 k 100 k 74. In the circuit shown in the figure, the switch is initially closed for 0.5 minutes and then opened. What is the input voltage if the output voltage is initially 0 and –5.4 V after the switch is opened ? A. B. C. D. 5.4 V -5.4 V 1.8 V 2.7 V 75. A 230 V – 0 – 230 V input voltage is connected to a full wave rectifier as shown in the figure. The value of Irms across the 1 kΩ load is A. B. C. D. 325.5 mA 207 mA 115 mA 230 mA 76. Given the op amp configuration in the figure, the value of Rf required to produce a closed loop voltage gain of 100 is A. B. C. D. 110 kΩ 480 kΩ 220 kΩ 440 kΩ 18 77. The maximum peak output voltage obtainable from a741 op-amp circuit with a 100 KHz frequency (SR = 0.5V / µs) is A. B. C. D. 0.79 V 0.25 V 0.95 V 0.40 V 78. For a JFET with IDSS = 15mA and Vgs(off) = -5 V, the drain current for Vgs = -2V is A. B. C. D. 58.8 mA 29.4 mA 9.6 mA 5.4 mA 79. If (11X1Y)8 = (12C9)16, then the values of X and Y are A. B. C. D. 3 and 1 5 and 7 7 and 5 1 and 5 80. In an 8085 microprocessor, the numbers are represented in signed 2's complement form as P = 11101101 and Q = 11100110. If Q is subtracted from P, the value obtained in signed 2's complement form is A. B. C. D. 100000111 00000111 11111001 011111001 81. An analog voltage of 3.4 V is converted into a 8-bit digital form by an A/D converter with the reference voltage of 5 V. The digital output is A. B. C. D. 11110001 10101110 10011001 10110111 82. A bistable multi-vibrator that functions as a voltage comparator with hysteresis is called A. B. C. D. D Flip Flop Schmitt Trigger T Flip Flop J-K Flip Flop 19 83. The Figure of Merit of a logic family is given by A. B. C. D. Gain Bandwidth Product (Propagation Delay Time) x (Power Dissipation) (Fan Out) x (Propagation Delay time) (Noise Margin) x (Power Dissipation) 84. The shift register shown in the figure is initially loaded with the bit pattern 1010. Subsequently the shift register is clocked, and with each clock pulse the pattern gets shifted by one bit position to the right. With each shift, the bit at the serial input is pushed to the left most position (MSB). After how many pulses will the content of the shift register become 1010 again? A. B. C. D. 15 3 7 11 85. The circuit shown below is functionally equivalent to which one of the following? A. B. C. D. OR Gate EX-NOR Gate EX-OR Gate NAND Gate 86. The circuit given below is that of a A. B. C. D. Mod-5 Counter Mod-7 Counter Mod-8 Counter Mod-10 Counter 87. The logic circuit realized by the circuit shown in the figure will be A. B. C. D. AC B C B C A C 20 88. The octal form of the decimal number A. B. C. D. is 231.42 231.41 231.40 None of the above 89. 10’s Compliment of the number 012398 is A. B. C. D. 987601 087602 987602 087601 90. The simplified form of the Boolean function ( A B)( A B ) is A. B B. 1 C. D. A 91. A logic circuit that gives a HIGH output for both inputs HIGH or both inputs LOW is A. B. C. D. an Ex-NOR gate an OR gate an Ex-OR gate a NAND date 92. For the Karnaugh map given below, the simplified Boolean function is A. B. C. D. 93. The 8-input XOR circuit shown has an output of Y = 1. Which input combination below (ordered A – H) is correct? A. B. C. D. 10111000 11100111 10111100 00011101 21 94. Which of the following flags in 8086 microprocessor get affected by the instruction CMP ? A. B. C. D. Trap Flag Carry Flag Parity Flag Sign Flag 95. Consider the following instructions executed in the 8086 microprocessor PUSH AX; AX 40 H in it PUSH BX; BX 18 H in it POP AX; POP G The value stored in G will be A. B. C. D. 28 H 12 H 40 H 68 H 96. Which of the following instructions of an 8086 microprocessor uses the content of a CX register as a counter? A. B. C. D. LOOP LOCK LDA CALL 97. In a 8086 microprocessor, if the content of the code segment register is 1FAB and the content of the IP register is 10A1, then the effective memory address is A. B. C. D. 1FBC0 30AC FDB5 20B51 98. Which one of the following interrupts is both level and edge sensitive? A. B. C. D. RST 7.5 RST 6.5 TRAP INTR 22 99. Which one of the following modes is required for 8253 to generate a square wave? A. B. C. D. MODE 1 MODE 3 MODE 2 MODE 4 100. The interface chip used for data transmission between 8086 and a 16-bit ADC is A. B. C. D. 8251 8253 8255 8259 101. The 8086 and 8253 run at 6 MHz and 1.5 MHz respectively. The number of T-states required to generate a square wave of period 1 ms is A. B. C. D. 1500 states 3000 states 6000 states 1000 states 102. After the following instruction is executed in a 8086 microprocessor LOAD X MULT Y STORE T1 LOAD Z ADD Y ADD T1 STORE R A. B. C. D. R = X+XY+Z R = X+Y+XZ R = XY+Y+Z R = XY+Y+XZ 103. To have multiprocessing capabilities of the 8086 microprocessor, the pin connect to the ground is A. B. C. D. MN / MX with logic 1 ALE INTR MN / MX with logic 0 23 104. By which of the following ways can a microprocessor come out of the HALT state? A. B. C. D. When HOLD line is logical 1 When the interrupt occurs and the interrupt system has been enabled When both A and B are true When either A or B are true 105. In the instruction FADD, F stands for A. B. C. D. Far Floppy File Floating 106. What will be the contents of register AL after the following has been executed ? MOV BL,8C MOV AL, 7E ADD AL,BL A. B. C. D. 0A and carry flag is reset 0A and carry flag is set 6A and carry flag is set 6A and carry flag is reset 107. READY pin of a microprocessor is used A. B. C. D. to introduce wait states to indicate microprocessor is ready to receive inputs to indicate microprocessor is ready to receive outputs to provide direct memory access 108. Pseudo instructions are basically A. B. C. D. false instructions instructions that are ignored by the microprocessor. instructions that are treated like comments assembler directives 109. A rectangular waveguide of internal dimensions a 4 cm , b 3 cm is to be operated in the TE11 mode. The minimum operating frequency is A. B. C. D. 6.0 GHz 3.75 GHz 5.0 GHz 6.25 GHz 24 110. For a Hertz dipole antenna, the half power beam width in the E-Plane is A. B. C. D. 360ο 180ο 45ο 90ο 111. The electric field of a time harmonic plane EM wave travelling in a non-magnetic, lossless dielectric medium has an amplitude of 1 V/m. If the relative dielectric constant of the medium is 4, the magnitude of the time averaged Poynting vector is A. 1 240 B. 1 60 C. 1 30 D. 1 120 112. A transmission line has a characteristic impedance of 50 Ω and resistance of 0.1 Ω/m. If the line is distortionless, the attenuation constant (in Np/m) is A. B. C. D. 0.002 5.0 500 0.014 113. The power radiated by a Hertzian dipole antenna fed by a peak current I 0 is given I 2 dl by P 0 0 . The radiation resistance of the antenna is approximately 3 2 A. 790 2 dl 2 B. 80 2 dl C. 80 2 dl D. dl 80 2 2 25 114. A monochromatic plane wave of wavelength 600 m with electric field amplitude E0 is incident on an air dielectric interface as shown in the figure; E i , E r and E t denote the incident, reflected and transmitted waves. If the angle of transmission t 30 deg . , the angle of incidence i and incident electric field E i are given by 10 4 A. 60 deg., j[t E 3 Ei 0 ( xˆ zˆ )e 2 B. 45 deg., Ei E0 ( xˆ zˆ )e j[t =1 10 4 ( x z )] 3 2 2 10 4 C. 60 deg., ( x z )] 2 j[t E 3 Ei 0 ( xˆ zˆ )e 2 ( x z )] 2 10 4 D. 45 deg. , j[t E 3 Ei 0 ( xˆ zˆ )e 2 ( x z )] 2 115. An electromagnetic wave is to pass through an interface separating two media with dielectric constants ε1 and ε2 respectively. If 1 4 2 , the wave will be totally reflected if angle of incidence is A. B. C. D. ᵒ 0 ᵒ 45 ᵒ 60 ᵒ 30 116. The magnitudes of the open circuit and short circuit input impedance of a transmission line are 100 Ω and 25 Ω respectively. The characteristic impedance of the line is A. B. C. D. 25 Ω 75 Ω 50 Ω 100 Ω 5 3 5 cos t z xˆ sin t z yˆ is the field of a plane wave 117. If H 0 0 2 propagating in free space is. The time average power flow density is A. o 100 100 B. o 50 C. o D. 50 o 2 26 118. The amplitude of the magnetic field of a plane wave propagating in a medium characterized by =0, =0 and =40 is 2A/m. The magnitude of the electric field will be A. B. C. D. 80 V/m 120 V/m 60 V/m 20 V/m 119. For a plane wave propagating in a lossless medium, the wavelength is 0.25 m and the frequency is 600 MHz. The permittivity of the medium will be A. B. C. D. 6 3 2 4 120. When a EM wave propagates in a lossy dielectric medium, as the conductivity increases the phase constant A. B. C. D. decreases remains unchanged zero increases 121. The medium 1 and 2 have relative permittivities 1 and 2, respectively, then Brewster's angle B for a wave travelling from medium 2 to medium 1 is A. tan B 1 2 B. tan B 2 1 C. tan B 1 2 D. tan B 2 1 2 122. If the Coulomb force acting on a charge of 10 C is F 3aˆ x 4aˆ y N, the magnitude of the electric field is A. B. C. D. 0.5 V/m 10 V/m 7 V/m 1.2 V/m 27 123. A coaxial cable with characteristic impedance 50 is insulated with a dielectric, whose relative permittivity is 1.0. The phase velocity of the waves on this coaxial cable at 10 GHz will be A. B. C. D. 2.71010 cm/s 3.61010 cm/s 31010 cm/s 1.91010 cm/s 124. A current distribution gives rise to A x 2 yiˆ y 2 xˆj 4 xyzkˆ Wb/m . B at (-1, 2, 5) is the vector magnetic potential A. 20 iˆ 40 ˆj 3kˆ Wb/m2 B. 20 iˆ 40 ˆj 3kˆ Wb/m2 C. 20 iˆ 40 ˆj 3kˆ Wb/m2 D. 20 iˆ 40 ˆj 3kˆ Wb/m 2 125. A dipole produces an electric field intensity of 1mV/m at a distance of 2 km. The field intensity at a distance of 4 Km will be A. B. C. D. 0.5 mV/m 1 mV/m 0.75 mV/m 0.25 mV/m 126. If binary PSK modulation is used for transmission the required minimum bandwidth is 9600 Hz. To reduce the transmission bandwidth to 4800 Hz, the scheme to be adopted should be A. B. C. D. Minimum Shift Keying Quadrature Phase-Shift Keying Amplitude Shift Keying Binary Frequency Shift Keying 127. If the baud rate is 400 for a QPSK signal, the bit rate in bits per second is A. B. C. D. 400 100 800 1600 128. Quadrature amplitude modulation (QAM) is a combination of A. B. C. D. ASK and PSK ASK and FSK PSK and FSK PCM and PSK 28 129. In a PCM system, if we increase the quantization levels from 2 to 8, how does the relative bandwidth requirement vary? A. B. C. D. Gets doubled Remains the same Gets tripled Becomes eight times 130. In a receiver the input signal is 100 µV, while the internal noise at the input is 10 µV. With amplification the output signal is 2 V, while the output noise is 0.4 V. The noise figure of receiver is A. B. C. D. 1 0.2 0.5 2 131. An AM signal is represented by modulation index is A. B. C. D. x(t ) (20 4 sin 500 t ) cos(2 10 5 t ) V . The 20 4 0.2 10 132. Four voice signals, each limited to 4 kHz and sampled at Nyquist rate are converted into binary PCM signal using 256 quantization levels. The bit transmission for the timedivision multiplexed signal will be A. B. C. D. 256 kbps 64 kbps 8 kbps 512 kbps 133. An antenna has directivity of 100 and operates at 150 MHz. The maximum effective aperture is A. B. C. D. 50 10 m2 cm2 100 1 m2 cm2 29 134. What is the unmodulated carrier power when P out= 50 W at 100% modulation and internal loss of the modulator is 10 W? A. B. C. D. 60 W 100 W 150 W 40 W 135. In an AM signal, the peak antenna current is 12 A and the minimum current is 4 A. The percent modulation is A. B. C. D. 30% 40% 50% 100% 136. A signal of maximum frequency of 10 KHz is sampled at Nyquist rate. The time interval between the two successive samples is A. B. C. D. 50 µs 100 µs 20 µs 5 µs 137. For attenuation of high frequencies we should use A. B. C. D. Series Capacitance Inductors Resistance Shunt Capacitance 138. A 400W carrier is amplitude modulated with modulation index m=0.75. The total power of AM wave is A. B. C. D. 400W 588W 650W 512W 139. Frequency shift keying is used mostly in A. B. C. D. Telephony Telegraphy Satellite Communication Radio Transmission 30 140. An FM signal represented by x(t ) 2000 sin[2 10 8 t 2 sin( 10 4 t )] is applied to a antenna. Its transmitted power is A. B. C. D. 40 kW 20 kW 80 kW 10 kW 141. The reason for using non-uniform quantization in PCM system is that it A. B. C. D. decreases quantization noise for low signal levels simplifies the quantization process leads to reduced transmission band width increases the maximum signal to quantization noise ratio 142. Which of the following is necessarily associated with flat-top sampling A. B. C. D. Aliasing effect Aperture effect Natural sampling Instantaneous sampling 143. A pre-emphasis circuit provides extra noise immunity by A. B. C. D. boosting the low frequencies amplifying the higher audio frequencies pre-amplifying the whole audio band converting the phase modulation to FM 144. For a given date rate, the BW B0, of OOK or ASK signals and BW Bp of PSK signal are related as A. B. C. D. Bp = B0 Bp = 0.5B0 Bp = 2B0 Bp < B0 145. Voice frequency range in a telephone system is restricted to about A. B. C. D. 0 to 4000 Hz 0 to 3400 Hz 300 to 3400 Hz 100 to 3600 Hz 31 146. A digital meter has a 3½-digit display and an accuracy of ± (0.6+1). The measurement accuracy for a 20 volt dc voltage will be A. ± 1.1 % B. ± 11.1 % C. ± 2.2% D. ± 22.2% 147. A 10 mA current is flowing through an 820 10% resistor. This current is measured using a 25 mA range analog meter that has 2% accuracy on the full scale. The percentage error in the calculated power is A. B. C. D. ± 12 % ±5% ± 20 % ± 10 % 148. A basic Q-meter circuit has 100 mV ac supply, R=5 and XL=XC=100 at resonance. The Q factor of the coil is A. B. C. D. 100 200 10 20 149. A pulse waveform with a 10 ns rise time is applied to an oscilloscope that has an upper cutoff frequency of 7 MHz, the displayed rise time will be A. B. C. D. 51 ns 21 ns 70 ns 60 ns 150. A permanent magnet movement coil instrument with 100 A FSD and a 1 k coil resistance is to be used in an ammeter. What will be the shunt resistance for a FSD of 100 mA? A. B. C. D. 10.01 100.1 0.1001 1.001 32 FOR ROUGH WORK 33 FOR ROUGH WORK 34 FOR ROUGH WORK 35 36