DO NOT OPEN THIS TEST BOOKLET UNTIL YOU ARE ASKED TO DO SO T.B.C. : Q·GUG·K·FUA Test Booklet Series Serial 062440 TEST BOOKLET ELECTRONICS & TELECOMMUNICATION··'ENGINEERING PAPER I Time Allowed : Two Hours Maximum Marks : 200 INSTRUCTIONS 1. IMMEDIATELY AFTER THE COMMENCEMENT OF THE EXAMINATION, YOU SHOULD CHECK THAT THIS TEST BOOKLET DOES NOT HAVE ANY UNPRINTED OR TORN OR MISSING PAGES OR ITEMS ETC. IF SO, GET IT REPLACED BY A COMPLETE TEST BOOKLET. 2. ENCODE CLEARLY THE TEST BOOKLET SERIES A, B, C, OR D AS THE CASE MAY BE IN THE APPROPRIATE PLACE IN THE ANSWER SHEET. 3. I You have to enter your Roll Number on the Test Booklet in the Box provided alongside. DO NOT write anything else on the Test Booklet. This Test Booklet contains 120 items (questions). Each item comprises four responses (answers). You will select the response which you want to mark on the Answer Sheet. In case you feel that there is more than one correct response, mark the response which you consider the best. In any case, choose ONLY ONE response for each item. You have to mark all your responses ONLY on the separate Answer Sheet provided. See directions in the Answer Sheet. All items carry equal marks. Before you proceed to mark in the Answer Sheet the response to various items in the Test Booklet, you have to fill in some particulars in the Answer Sheet as per instructions sent to you with your Admission Certificate. After you have completed filling in all your responses on the Answer Sheet and the examination has concluded, you should hand over to the Invigilator only the Answer Sheet. You are permitted to take away with you the Test Booklet. 9. Sheets for rough work are appended in the Test Booklet at the end. 10. Penalty for wrong answers: THERE WILL BE PENALTY FOR WRONG ANSWERS MARKED BY A CANDIDATE IN THE OBJECTIVE TYPE QUESTION PAPERS. (i) There are four alternatives for the answer to every question. For each question for which a wrong answer has been given by the candidate, one-third (0'33) of the marks assigned to that question will be deducted as penalty. (ii) If a candidate gives more than one answer, it will be treated as a wrong answer even if one of the given answers happens to be correct and there will be same penalty as above to that question. (iii) If a question is left blank, i.e., no answer is given by the candidate, there will be no penalty for that question. 4. 5. 6. 7. 8. DO NOT OPEN THIS TEST BOOKLET UNTIL YOU ARE ASKED TO DO SO l1. 1 ohm 1 Henry ------7 i(t) vet) = t u(t) The current in the above network is (aJ"J t -1 + e-t I u(t) « ,(b) I t2 -t + e-t I u(t) /' .>, .. \ \ ." , ,.:,.' .' (c) < It + 1 + e-t I u(t) It -1 -e-t I u(t) /1 .6 i ._L 1 L ,.. !...., . '\ (d) 2. When waves travel along a transmission line from a generator to a load, through which region is power transmission taking place? (~._Only through the conducting region (b) Only through the non-conducting re~~ ~ (c) Both through conducting and non-conducting regions (d) Through the conducting regions for half a cycle and through the non-conducting regions for the next half cycle 3. x(t) r-_+--_+------l_--+_--L __ ~ t -2 -1 1 2 o The mathematical model of the above shown signal is (a) x(t) = u(2 + t) (b) x(t) = u(t -2) (cJyrx(t) = u(2 -t) (d) x(t) = u(t -1) Q-GUG-K-FUA ( 2 -D ) 4. Consider the following statements : 1. Power factor will be unity. 2. Current in circuit will be maximum. 3. Current in circuit will be minimum. Which of these statements are correct with respect to resonance in R-L-C parallel circuit? (a) 1, 2 and 3 (b) 1 and 2 only (c) 2 and 3 only (d&A and 3 only 5. Number of state variables of discrete time system, described by 3 1 yln] --yln -1] + -yln -2] = xln] 4 8 IS (~ (b) 3 (c) 4 (d) 1 Which of the following pair of values of Land C should be used in a tank circuit to obtain a resonant frequency of 8 kHz? The bandwidth is 800 Hz and winding resistance of the coil is 10 ohms. (a) 2 mR and 1 JlF (b) 10 Rand 0·2 JlF (~_'1'99 mR and 0·2 JlF (d) 1·99 mR and 10 JlF 7. An elliptically polarized wave travelling in the positive Z-direction in air has x and y components EX = 3 sin (rot -~z) Vim Ey = 6 sin (rot -~z + 75°) Vim If the characteristic impedance of air is 360 n, the average power per unit area conveyed by the wave is (a) 8 W/m2 (b) 4 W/m2 (c) 62·5 mW/m2 (d) 125 mW/m2The value of a resistance as measured by a 12. Wheatstone bridge is 10·0 K using a voltage source of 10·0 V The same resistance is measured by the same bridge using 15·0 V The value of resistance is (a) 15·0 K (b) 15·5 K (c) 16·6 K "V .} P 'l. .. c. (d) 10·0 K 9. In the case of ABeD parameters, if all the impedances in the network are doubled, then 13. (av and D remain unchanged, e is halved and B is doubled (b) A, B, e and D are doubled (c) A and B are doubled, e and Dare unchanged (d) A and D are unchanged, e is doubled and B is halved 10. Unit step response of the system described by the equation yen) + yen -1) = x(n) IS (a) Z2 \../"(Z + 1)(Z -1) (b) Z (Z + 1)(Z -1) (c) Z+l Z-1 Z(Z -1) (Z + 1) (d) 11. functions for of continuous the time The transfer representation system: q (t) = Aq(t) + bx(t) yet) = cq(t) + dx(t) is given by ,. I .( (wc (sl -Ar! b + d (b) b (sl -Arl b + d (c) c (sl -Ar! b + d (d) d (sl -Arl b + c Q-GUG-K-FUA state LTl 14. ( 3 -D )The diffusion length for holes Lp, is the (a) Average distance which an injected hole c /travels before recombining with an electron (b) Maximum distance travelled by a hole before recombining with an electron Length of the region in which diffusion takes place Minimum distance travelled by a hole before it recombines with an electron (c) (d) 1 ohm 1 ohm 1ohm v + 1 The above network contains resistors and V2 controlled sources. Gl2 = -IS Vj (a) 4 --5 ~ (b) 3 --5 (c) 2 --'-5 (d) 1 --5 The frequency response H(D) of a system for impulse sequence response h[n] = o[n] + o[n -1] is (~YI(n) = 2 cos (~) L -~ (b) H(D) = cos D L -D (c) Q H(D) = 2 cos D L --2 Q H(n) = 2 L --2 (d)15. Consider the following statements : The inter element spacing of 1. More than "-in array antenna will produce grating lobes in unscanned condition. 2. More than "-/2 but less than "-in array antenna will produce grating lobe under scanned condition. 3. Less than "-/2 in array antenna will not produce any grating lobe. 4. More than 1·5 "-in array antenna will not produce any grating lobe. Which of the above statements are correct ? (a) 1and 2 only (b) 3 and 4 only (c) 1, 2 and 3 only (d) 1,2,3 and 4 16. Match List I with List II and select the correct answer using the code given below the lists : 19. List I (Excitation) A. II' 12 B. VI'V2 C. V1,I2 D. 11' V2 Code:A B (V 2 (b) 4 2 (c) 1 3 (d) 4 3 Q-GUG-K-FUA List II (Two-port parameters) 1. z 2. y 3. g 4. h 17. Consider the following statements symmetrical T section : 1. Z11 and Z22 are equal. ~\( 2. Z12 and Z21 are equal. 3. Z11 and Z12 are equal. 4. Z21 and Z22 are equal. Which of the above statements are correct? (av1 and 2 only (b) 2 and 3 only (c) 3 and 4 only (d) 1, 2, 3 and 4 18. The magnetic flux density B and the vector magnetic potential A are related as (al,/B = V x A (b) A = V x B (c) B = V. A (d) A = V • B . \ '\.. Two milli ammeters with full scale currents of 1 mA and 10 mA are connected in parallel and they read 0·5 mA and 2·5 mA respectively. Their internal resistances are in the ratio of (a) 1: 10 (b) 10: 1 (c) 1: 5 (d) 5: 1 20. The Fourier transform of unit step sequence is (a) 1rO (n) C D 1 (b) 3 4 1-e-jQ 3 1 (W no «» + 1'Q 2 4 1-e-J (d) 1 -jQ 2 1 -e ( 4 -D )22. If\''( \\.. A long 1 metre thick dielectric (E = 3 Eo) slab 24. occupying the region 0 < x < 5 is placed perpendicularly in a uniform electric field Eo = 6ax' The polarization Pi inside the dielectric is (a) 4 Eo ax (b) 8 Eo ax (c) 36 Eo ax (d) Zero 1 4 2 3 t 30A (. The power dissipated in the 1n resistor is 1 W due to the 5 V voltage source alone and 576 W due to 30 A current source alone. The total power absorbed in the same resistor due to both the sources is )0 (a) 577 W (b) 575 W (<>L/625 W (d) 529 W 23. Consider the following statements regarding an FET: 1. Its operation depends upon the flow of majority carriers only. 2. It has a high input resistance. 3. It is suitable for high frequency. 4. Its operation depends upon the flow of both majority and minority carriers. Which of the above statements are correct ? (a) 1, 2, 3 and 4 (b) 1 and 2 only (\1,/2 and 3 only (d) 3 and 4 only Q-GUG-K-FUA yA ~ __ -t=D_-7X Consider points A, B, C and D on a circle of radius 2 units as in the above figure. The items in List II are the values of al» at different points on the circle. Match List I with List II and select the correct answer using the code given below the lists: List I List II A. 1. ax B. 2. ay C. 3. -ax D. 4. (ax + ay) /12 5. -(ax + ay) /12 6. (ax -ay)/12 Code:A B C D (a) 3 4 5 2 (b) 1 6 5 2 (c) 1 6 2 '4 (d) 3 5 4 2 •25. The incorrect statement is (a) Thermistor has a high sensitivity. (b) Thermocouple does external electrical operation. not require an source for its (c) Platinum has a linear R -T relationship. (o/fhermistor does not require an external electrical source for its operation. 26. In ionic crystals, electrical conductivity is (a) Very high (b) Depends on material (0/Depends on temperature (d) Practically zero 27. Consider the following statements: 1. The Laplace transform of the unit impulse function is s x Laplace transform of the unit ramp function. 2. The impulse function is a time derivative of the ramp function. 30. 3. The Laplace transform of the unit impulse function IS s x Laplace transform of the unit step function. 4. The impulse function is a time derivative of the unit step function. Which of the above statements are correct ? (a) 1 and 2 only (0/3 and 4 only (c) 2 and 3 only (d) 1, 2, 3 and 4 Q-GUG-K-FUA 28. The flux and potential functions due to a line charge and due to two concentric circular conductors are of the following form: 29. LED is a (o/i>-n diode 3 (b) Thermistor (c) Gate (d) Transistor ( 6 -D ) (a) Concentric circular equipotential lines and straight radial flux lines (b) Concentric circular flux lines and straight equipotentiallines (c) Equipotentials due to line charge are concentric cylinders and equipotentials due to two conductors are straight lines (d) Equipotentials due to line charge are straight flat surfaces and those due to two conductors are concentric cylinders 1 --+ R L v Voltage and current expressions for the above circuit are given at t 2: 0 as v = 125 e-50t V, i = 5 e-50t A. The value of L will b~ (a) 0·005 H (b) 0'05 H (clrlO'5 H (d) 5 H , " 3(Consider the following statements: 34. Fourier series of any periodic function X(t) can be obtained if 1 1. f Ixlt) Idt < 00 o 2. Finite number of discontinuous exist within finite time interval t. Which of the above statements is/are correct ? (a) 1 only (bV2 only (c) Both 1 and 2 (d) Neither 1 nor 2 32. In a variable type carbon resistor the carbon track is formed of a mixture of carbon, resin and (~Clay (b) Manganese (c) Nickel (d) Cadmium 33. A standard air filled waveguide WR-187 has inside wall dimensions of a = 4·755 em and b = 2·215 em. At 12 GHz, it will support (a) TElO mode only , ,. o· (b) TElO and TEzo modes only (c) TElO' TEzo and TEol modes only Q-GUG-K-FUA ( 7 -0 ) A single strain gauge of resistance 120 n is mounted along the axial direction of an axially loaded specimen of steel (E = 200 GPa). The percentage change in length of the rod due to loading is 3% and the corresponding change in resistivity of strain gauge material is 0·3%. For a Poisson's ratio of 0,3, the value of the gauge factor is (a) 1·3 (b) 1·5 (c) 1·7 (d) 2·0 10 mB 35. In the above shown circuit, the independent current source generates zero current for t < 0 and a pulse 5 t e-4t A, for t > O. At what instant of time, will the current attain the maximum value in the circuit? (a) 0·25 sec (b) 0·5 see (c) 1 sec (d) 2 see 36. Frequency scaling rrelationship discrete time frequency (m and time frequency (w)] is defined as between continuous (a) W = 2 n (b) w = 2 Ts/0. (c) n = 2 wiTs37. The intrinsic impedance of copper at 3 GHz 41. (with parameters : 11 = 41( x 10-7 Him; E = 10-79/361(; and IT = 5·8 x 107 mho/m) will be (a) 0·02 ejn/4 ohm (b) 0·02 ejn/2 ohm . /2 (c) 0·2 eJn ohm . /4 (d) 0·2 eJn ohm 38. t=O ~ 10Q ~ ~3F tOV 1 r ~V;-6F In the circuit shown above, switch S is closed at t = O. The time constant of the circuit and • initial value of current i(t) are ( 8 -0 ) 1,;'.'1-. (a) 30 see, 0·5 A (b) 60 see, 1·0 A (c) 90 see, 1·0 A (~,.20 see, 0·5 A 39. A voltage source .of 240 volts having an internal impedance of (3 -j4) n is supplying power to a complex load impedance Z1' What will be the maximum power transferred to the load? switch is closed at t = a li(t) lOV lQ lQ (a) 2·4 kW (b) 3·6 kW (¥4'8 kW (d) 6·0 kW 40. Atomic number of silicon is IF (a) 12 (b) 13 (cV14 (d) 15 Q-GUG-K-FUA The value of the current i(t) in amperes in the above circuit is (a) O· (W10 (c) 10 e-t (d) 10 (1 -e-t) 42. A short current element has length l = 0·03 A, where A is the wavelength. The radiation resistance for uniform current distribution is (a) 0·072 1(2 o (b) 80 1(2 n (0/72 n (d) 80 o 43. If random process X(t) and Yet) are orthogonal then (avxy(f) = 0 (b) Sxy(f) = Sx( ) = Sy( ) (c) ~(T) = h(T) (d) H(f) = a 44. A first order circuit is excited with a dc source. The current i(t) through any element of the circuit can be written as (if and ij are the final and initial values, respectively, of the current) t (a) i. -(i, -if) e T 1 1 . t (bvr;: -(if -ij) e T i,. (c) t . (i . ) T 1· -If -1· e 1 1 (d) t if -(ij -if) e TMatch List I with List II and select the correct 47. answer using the code given below the lists: List I List II Y A. d a = 900 1. $x -= 0·25 ).. , Y B. i=0'5 a = 00 2. fErx A ' Y 48. C. i = 0·5 a = 1800 3. X "' A ' n :e. he .al It) Y D. i = 1·0 a = 1800 4. ~x A ' Code: --A B C D (a) 4 3 1 2 (b) 2 1 3 4 \.. 49. (c) 4 1 3 2 (d) 2 3 1 4 46. The output of a linear system for step input is, t2 e-2t. Then the transfer function is (a) s (b) 2s (s + 1)3 (c) s (d) 1 Q-GUG-K-FUA ( 9 -D ) In a three element Vagi antenna (a) All the three elements are of equal length (b) The driven element and the director are of equal length but the reflector is longer than both of them (o/The reflector is longer than the driven element which in turn is longer than the director (d) The reflector is longer than the driven element which in turn is longer than the reflector Consider the following statements regarding depth of penetration or skin depth in a conductor: It increases as frequency increases. It is inversely proportional to square root of 11 and cr. It is inversely proportional to square root of f. 4. It is directly proportional to square root of 11 and cr. Which of the above statementsare correct ? (a) 1 and 2 only (b) 3 and 4 only (<;2../2 and 3 only (d) 1, 2, 3 and 4 1. 2. 3../Consider the following statements regarding the use of Laplace transforms and Fourier transforms in circuit analysis: 1. Both make the solution of circuit problems simple and easy. 2. Both are applicable for the study of circuit behaviour for t -a to a. 3. Both convert differential equations to algebraic equations. 4. Both can be used for transient and steady state analysis. Which of the above statements are correct ? (atfi, 2, 3 and 4 (b) 2, 3 and 4 only (c) 1, 2 and 4 only (d) 1, 3 and 4 only50. The mode with lowest cutoff frequency for an 54. electromagnetic wave propagating between two perfectly conducting. parallel plates of infinite extent is (WTElO (b) TMlO (c)· TMol (d) TEM 51. Encoder (a) Assigns quantized values (bUChanges quantized values to binary values (c) Changes quantized values to numerical values (d) Changes numerical values to binary 55. values 52. Consider the following statements : 1. (Electric or magnetic) field must have two orthogonal linear components. 2. The two components must have the same magnitude. 3. The two components must have a time-phase difference of odd multiples of 90°. Which of these are the necessary and sufficient conditions for a time-harmonic wave to be circularly polarized at a given point in space? (a) 1 and 2 only (b) 2 and 3 only (CV1, 2 and 3 (d) 1 and 3 only 53. If the response of LTI continuous time system . . . (1 1 -2t) th to unit step input IS '2 -'2 e , en impulse response of the system is (a) (~_~e-2t) (tzY{e-2t) (c) (1 -e-2t) (d) Constant Q-GUG-K-FUA Consider the following statements regarding Thermistor: 1. It has a high sensitivity. 2. It has a linear relationship with temperature. 3. It is a resistive device. 4. It can be used as a time-delay device. Which of the above statements are correct ? (a) 1, 2, 3 and 4 (b) 2, 3 and 4 only (c) 1, 3 and 4 only (~1, 2 and 3 only In cylindrical waveguides the attenuation will be minimum, at a frequency which is J3 times the cutoff frequency for the following modes of operations: 1. TElO 2. TMn 3. TMlO 4. TEn Which of the above are correct ? (a) 1, 2, 3 and 4 (b) 2 and 3 only (c) 1 and 2 only (d) 3 and 4 only 56. In a junction transistor, recombination of electrons and holes occurs in (a) Base region only (b) Emitter region only (c) Collector region only () All the 3 regions 57. Given a range of frequencies, which of the following systems is best for transmission line load matching? (a) Single stub (b) Double stub (cVSingle stub with adjustable position (d) Quarter wave transformer (10 -0 )(a) 40° (b) 5° (c) 10° (d) 20° 8Q 4 Q ~ \ _is.,T3 F 1H t=Ol 6F An axial magnetic field is applied to a 61. cylindrical rod. The Faraday rotation of a plane polarized beam after emergence from the rod is 5°. If both the field and length of the rod are doubled, then the angle of rotation ISConsider the following statements relating to the cavity resonator: 1. The cavity resonator does not possess as many modes as the corresponding waveguide does. 2. The resonant frequencies of cavities are very closely spaced. 3. The resonant frequency of a cavity resonator can be changed by altering its dimensions. Which of the above statements is/are correct ? (a) 2 and 3 only (0/2 only (c) 3 only (d) 1, 2 and 3 60. Consider the following statements: For a rectangular waveguide with dimensions a x b where b is the narrow dimension, small value of b 1. Gives a larger separation between cutoff frequencies of TEol and TElO modes. 2. Gives increased attenuation. 3. Limits power handling capabilities because of breakdown field limits. Which of the above statements is/are correct ? (a) 1 and 2 only (~, 2 and 3 (c) 2 only (d) 3 only Q-GUG-K-FUA ( 11 -D ) 12 V In the circuit shown above, the switch is closed after a long time. The current is (0+) through the switch is (a) 1 A (b) 2/3 A (c) 1/3 A 62. If a random process Xtt) IS ergodic then, statistical averages (a) and time averages are different (~nd time averages are same (c) are greater than time averages (d) are smaller than time averages 63. The correct statement is (a) Microtrip lines can support pure TEM mode of propagation but shielded coaxial lines cannot (b) Microtrip lines cannot support pure TEM mode of propagation but shielded coaxial lines can (cVBoth microtrip lines and shielded coaxial lines can support pure TEM mode of propagation (d) Neither microtrip lines nor shielded coaxial lines can support pure TEM mode of propagation64. R + (0/1 (b) 00 (c) 0 (d) j 68. + 24Q 8Q 67. Aline of characteristic impedance 50 ohms is terminated at one end by +j50 ohms. The VSWR on the line is For the network shown above I = (0·2 V -2) A, (I = the current delivered by the voltage source V). The Thevenin voltage Vth and resistance Rth for the network N across the terminals AB are respectively 69. 4Q SOQ 200V 24 V ( 12 -D ) + 50V 20 Q 1 The value of current i.n SO0 resistor of above circuit is (0/'0·5 A (b) 2·0 A (c) 5·0 A (d) 20·0 A A B The value of R in the above circuit is (a) 40 (b) 400 (0/440 (d) 440 0 65. B 2Q lOV 3Q A I 3Q 2Q Thevenin equivalent voltage VAB and resistance R, across the terminals AB in the above circuit are (a) 6 V, 50 (b) 4 V, 50 (c~2 V, 2·40 (d) 2 V, 2·50 N (a) -10V, 5 Q (0/10 V, 5 Q (c) -10 V, 0·2 Q (d) 10 V, 0·2 Q 66. Z and Laplace transform are related by (a) s = In z ln z (b) s = -T (~=z T (d) s =-In z Q-GUG-K-FUA71. Alumina is a (~electric (b) Ceramic (c) Semiconductor Cd) Conductor 72. At UHF short-circuited lossless transmission lines can be used to provide appropriate values of impedance. Match List I with List II and select the correct answer using the code given below the lists : + 100 V Vs 73. Convolution of two sequences X1[n] and X2[n] is represented as (a) X1(z) * Xz(z) (VI(z) X2(z) (c) X1(z) + Xz(z) (d) X1(z)/Xz(z) 74. A half-wave dipole working at 100 MHz in free space radiates a power of 1000 Watts. The field strength at a distance of 10 kms in the direction of maximum radiation is (a) 1·73 mV/m (b) 2·12 mV/m (c) 2·22 mV/m Cd) 22·2 mV/m 75. What is the voltage across the load resistance, ~ in the above circuit ? The value of each resistor connected in the circuit is 10 n. (a) 3·33 V (bU'33'33 V (c) 333·33 V (d) 0 V List I List II A. 1< 'A/4 1. Capacitive B. I = A/4 < I < A/2 2. Inductive C. 1= 'A/4 3. 0 D. 1= 'A/2 4. 00 120Q 60Q 220V l 200V 200V l 220V In the circuit shown above, the current through RL is (V6A (b) 4 A (c) 2 A (d) 0 '-76. Decimation is the process of Code:A B C D (a) Retaining sequence values of Xp[n] other than zeroes (V 1 4 3 (b) 3 1 4 2 (b) Retaining all sequence values of Xp[n] (c) 2 4 1 3 (c. ividing the sequence ~alue by 10 (d) 3 4 1 2 (d) Multiplying the sequence value by 10 Q-GUG-K-FUA ( 13 -' D )'iI I 81. The driving point impedance of a network given by Z(s) = 2s + 1 . The Foster realization s(s + 1) 8 Q of the network is 77. 28Q An air-filled rectangular waveguide has dimensions of a = 6 em and b = 4 cm. The signal frequency is 3 GHz. Match List I with List II and select the correct answer using the code given below the lists : List I List II -----A. TElO 1. 2·5 GHz B. TEOl 2. 3·75 GHz C. TEll 3. 4·506 GHz D. TMn 4. 4·506 GHz Code: . (a) (b) (~ (d) A (av (b) 4 (c) 1 (d) 4 IH 5A~ Q-GUG-K-FUA ( 14 -0 ) I ohm 4Q IF I ohm IH I ohm IHIF .\ 1J B2233 -v-\ In the circuit shown above, the current Iis (a) 1 A (V:'5 A (c) 2·5 A (d) 4 A 78. It is required to find the current through a particular branch of a linear bilateral network without mutual coupling when the branch impedance takes four different values. Which one of the following methods will be preferred? (a) Mesh analysis /' (b0hevenin's equivalent circuit (c) Nodal analysis (d) Superposition theorem 79. A source having internal impedance of 82. (9 + j12) Q is to deliver maximum power to a resistive load. The load resistance should be (aV9Q (b) 12 Q (c) 15 n (d) 21 Q 80. There' are two conducting plates of sizes 1 m x 1 m and 2 m x 2 m. Ratio of the capacitance of the second one with respect to that of the first one is l ~i ". (~4 (b) 2 (c) 1/2 (d) 1/4 C3322 D414186. Match List I with List II and select the correct answer using the code given below the lists : List I List II (Transducers) (Type of transducer) A. L.V.D.T. 1. Resistive B. Strain Gauge 2. Inductive C. Dielectric 3. Capacitive Gauge D. Thermocouple 4. Self generating Code:A B C D (a) 2 3 1 4 (b) 4 3 1 2 (~ 1 3 4 (d) 4 1 3 2 If X(to = 8(to -(j) 0) then X(t) is (a) e-jOlot \. l.. (b) 8(t) (d) 1 84. An electric charge of Q coulombs is located at the origin. Consider electric potential V and electric field intensity E at any point (x, y, z). Then (a) E and V are both scalars (b) E and V are both vectors (c) E is a scalar and V is a vector (d) I' E is a vector and V is a scalar V 85. Consider the following statements regarding a transmission line : Its attenuation is constant and IS independent of frequency. 87. 1. Consider the following: ' In a parallel plate capacitor, let the charge be held constant while the dielectric material is replaced by a different dielectric. Consider seh Its attenuation varies linearly with frequency. 2. e 3. Its phase shift vanes linearly with frequency. 1. Stored energy. 2. Electric field intensity. 4. Its phase shift is constant and IS independent of frequency. 3. Capacitance. Which of these changes ? Which of the above statements are correct for distortionless line ? (a) 1 only (b) 1and 2 only (c) 2 and 3 only '\' ~. (a) 1, 2, 3 and 4 (b) 2 and 3 only (c) 1 and 3 only (d) 3 and 4 only (~1, 2 and 3 Q-GUG-K-FUA . ( 15 -0 )I 88. ,-----;~I __ ,-------, c( 16 -D ) 90. Consider the following statements : They are given as necessary conditions for 1Q driving point functions with common factors in p(s) and q(s) cancelled: 1. The coefficients of the polynomial in pts) and qts) must be real. 2. Poles and zeroes must be conjugate pairs if imaginary or complex. 3. The terms of lowest degree in p(s) and q(s) may differ in degree by one at most. Which of the above statements is/are correct? + 1 V u~v1,2 and 3 (b) 1only (c) 1 and 2 only (d) 2 and 3 only 91. For distortionless transmission through LTI system phase of H(co) is (a) Constant (b) One (c) Zero () Linearly dependent on (() 92. Consider the following statements : 1. The coefficients in the polynomials pis) and q(s) must be real and positive. 2. Poles and zeroes of z(s) must be conjugate if imaginary or complex. Which of these statements are associated with the driving point function Z(s) = p(s) ? q(s) V rv -w = 1rls 1H (a) Both 1 and 2 (WI only (c) 2 only (d) Neither 1 nor 2 -In the above circuit, the value of C for the circuit to exhibit a power factor of 0'86, is approximately (a) 0·4 F (b) 0·6 F (c) 1·4 F (d) 0·1 F 89. A long straight non-magnetic conductor of radius 8 mm is carrying a uniform current density of 100 kA/m2 in the az direction. For this case, which one of the following is not correct ? (a) V x H = 105 aZ Nm2 for 0 < p < 8 mm (b) V x B = 0 (c) The magnetic field intensity for . 105 P > 8 mm is 2pa~ Nm (d) The total current carried by the conductor is 6·4 11: A I! Q-GUG-K-FUAurs md at 'ire ~TI be 93. Consider the following statements relating to 96. the electrostatic and magneto static fields : 1. The relative distribution of charges on an isolated conducting body is dependent on the total charge of the body. 2. The magnetic flux through any closed surface is zero. Which of the above statements is/are correct? (~either 1 nor 2 (b) 1 only (c) 2 only (d) Both 1 and 2 ( 17 -D ) A circuit consists of two clocked JK flip-flops connected as follows : J0 = Ko = Ql' J1 = Qo and Kl = Qo' Each flip-flop receives the clock input simultaneously. The circuit acts as a t \ ' (~ Counter of mod 3 \ '\:' ~~ .) •.... . . ,. \ 4,., .•.4 ~. , ~, /,,\ 1\.,. 94. The crystal in which atoms are chemically highly inactive and they do not form compounds with other atoms is (a.&/Ionic crystal (b) Metal (c) Valence crystal (d) Van der Waals crystal (b) Counter of mod 4 (c) Shift-left register (d) Shift-right register 97. Which one of the following IS not a ferromagnetic material ? (a) Cobalt (b) Iron (c) Nickel (d) Bismuth \.,,/0-' 5Q 5Q 5Q + + -----:) II ~ + 5Q 2 VI 5Q vz V2 95. A two-port network has the ABCD parameters [7 8]. Two such identical networks are 3 4 , cascaded. The ABCD parameters of the overall cascaded network will be 98. With reference to the above network the value of Zll will be , ,. \. ) . \ (a) -3 , 1 (b) 3 (c) -1 (d) -5 (c) (d) 64] 16 Q-GUG-K-FUA99. When donor atoms are added to Directions: Each of the next twenty (20) items semiconductor, it consists of two statements, one labelled as the 'Assertion (A)' and the other as 'Reason (R)'. You are to examine these two statements carefully and select (a) Increases the energy band gap of the the answers to these items using the codes given semiconductor below .' (b) Decreases the energy band gap of the semiconductor (c) Introduces a new narrow band gap near the conductor band (~Introduces a new discrete energy level below the conduction band 100. t=o 1V IH Codes: (a) Both A and R are individually true and R is the correct explanation of A (b) Both A and R are individually true but R is not the correct explanation of A (c) A is true but R is false (d) A is false but R is true 101. Assertion (A).' A linear system gives a bounded output if the input is bounded. Reason (R).' The roots of the characteristic equation have all negative real parts and the response due to initial conditions decay to zero as time t tends. to infinity. 102. Assertion (A) .' The value of V that would result in a -=, The system described by y2(t) + 2y(t) = x2(t) + x(t) + c is a linear and static system. Reason (R).' The dynamic system IS characterized by differential equation. 103. Assertion (A).' When five percent of silver is added to copper to form an alloy, the electrical resistivity of the alloy is more than that of pure copper. Reason (R):' Silver has a higher value of resistivity than that of copper .. 10 Q IOQ IOU 1 steady-state current of 1 A through the inductor in the above circuit is (~30V (b) 15V (c) 20 V (d) 25 V Q-GUG-K-FUA ( 18 -0 ) 1]f 104. Assertion (A): Magnetic susceptibility value of an antiferromagnetic substance at 0° K is zero. Reason (R) : At 0° K, atomic magnetic moments are frozen with magnetic dipoles pointing III random directions. 109. Assertion (A): In an intrinsic semiconductor, the concentration of electrons and holes increases with increase in the temperature. Reason (R): Law of mass action holds good in case of semiconductors. 105. Assertion (A): A thermocouple is an active 110. Assertion (A) : component. Reason (R) : It IS activated by a temperature gradient. 106. Assertion (A): Synthesis problem IS not unique in the sense that we . may be able to find more than one network which provides prescribed response. Reason (RJ : The problem of synthesis deals with the design and specification of the network. 107. Assertion (A): In an intrinsic semiconductor, electron mobility in conduction band is different from hole mobility in valence band. Reason (R) : In an intrinsic semiconductor, electrons and holes are created solely by thermal excitation across the energy gap. 108. Assertion (A): At very high temperatures, both p and n-type semiconductors behave as intrinsic semiconductor. Reason (R) : In n-type semiconductor the majority carriers are electrons and in a p-type semiconductor the majority carriers are holes, whereas III an intrinsic semiconductor the number of holes and electrons are equal. Q-GUG-K-FUA Capacitance between two parallel plates of area 'A' each and distance of separation 'd' is EA/d for large Aid ratio. Reason (R) : Fringing electric field can be neglected for large Aid ratio. 111. Assertion (A) : In solving boundary value problems, the method of images is used. Reason (R) : By this technique, conducting surfaces can be removed from the solution domain. 112. Assertion (A): The velocity of light in any medium is slower than that of vacuum. Reason (RJ: The dielectric constant of the vacuum is unity and is lesser than that of any other medium. 113. Assertion (A): To obtain high Q, a resonator should have a large ratio of volume to surface area. Reason (R): It is the volume that stores energy and it is the surface area that dissipates energy. ( 19 -D )TEM (Transfer Electro 118. Assertion (A): If we have two p-n-p and n-p-n Magnetic) waves cannot transistors of identical ,propagate within a hollow waveguide of any shape. 116. Assertion (A): The short-circuit current gain of a bipolar junction transistor, in common base configuration Reason (R) : increases with increase in the reverse bias collector to base voltage. 114. Assertion (A) : Reason (R): For a TEM wave to exist within the waveguide, lines of H field must be closed loops which requires an axial component of E which is not present in a TEM wave. 115. Assertion (A): Si is mainly used for making ICs and not Ge. Reason (R): In Si, 8i02 layer which acts as an insulator can be formed for isolation purposes. Corresponding oxide layer cannot be formed in Ge. Reason (R) : With' increase in bias collector to the effective decreases. the reverse base voltage, base width 117. Assertion (A): A bipolar junction transistor is basically a current amplifier. Reason (R): The most simplified model of a BJT has a current dependent current source in its output circuit, whose magnitude directly depends upon the input current. Q-GUG-K-FUA ( 20 -D ) construction, the n-p-n transistor will have better frequency response characteristic compared to the p-n-p transistor. Reason (R): The diffusion constant of electron is higher than that of holes. 119. Assertion (A) : Many semiconductors where minimum energy in the conduction band and maximum energy in the valence band occur at the same ~ value of k (wave vector), are preferred for optical lenses. For such semiconductors, the efficiency of carrier generation and recombination is very high. 120. Assertion (A): At low temperature, conductivity of a semiconductor increases with the increase in the temperature. Reason (R): The breaking of the covalent bonds increases with increase in the temperature, generating increasing number of electrons and holes. Q