IES-2010 IES Academy ET (Paper-I) Electronics Engineering (Paper-I)

India’s No 1IES AcademyIES-2010ET (Paper-I)Electronics Engineering (Paper-I)Time Allowed: Two Hours Maximum Marks: 200INSTRUCTIONS1. IMMEDIATELY AFTER THE COMMENCEMENT OF THE EXAMINATION, YOUSHOULD CHECK THAT THIS TEST BOOKLET DOES NOT HAVE ANYUNPRNTED OR TORN OR MISSING PAGES OR ITEMS, ETC. IF SO, GET ITREPLACED BY A COMPLETE TEST BOOKLET2. ENCODE CLEARLY THE TEST BOOKLET SERIES A, B, C OR D AS THE CASEMAY BE IN THE APPROPRIATE PLACE TN THE ANSWER SHEET.3. You have to enter your Roll Number on the Test Booklet in the Box providedalongside. DO NOT write anything else on the Test Booklet.4. This is Test Booklet contains 120 items (questions). Each item comprises fourresponses (answers). You will select the response which you want to mark on theAnswer Sheet. In case you feel that there is more than one correct response, markthe response which you consider the best. In any case, choose ONLY ONE responsefor each item.5. You have to mark all your responses ONLY on the separate Answer Sheet provided.See directions in the Answer Sheet.6. All items carry equal marks.7. Before you proceed to mark in the Answer Sheet the response to various items in theTest Booklet, you have to fill in some particulars in the Answer Sheet as perinstructions sent to you with your Admission Certificate.8. After you have completed filling in all your responses on the Answer Sheet and theexamination has concluded, you should hand over to the Invigilator only the AnswerSheet. 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 ACANDIDATE IN THE OBJECTIVE TYPE QUESTION PAPERS.(i) There are four alternatives for the answer to every question. For each questionfor which a wrong answer has been given by the candidate, one-third (0.33) ofthe 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 answereven if one of the given answers happens to be correct and there will be samepenalty as above to that question.(iii) If a question is left blank, i.e., no answer is given by the candidate, there, will beno penalty for that question.DO NOT OPEN THIS TEST BOOKLET UNTIL YOU ARE ASKED TO DOwww.iesacademy.com Email: iesacademy@yahoo.com Page-1__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010ET (Paper-I)jω+46−ω + 5jωQ1. A causal stable LTI system S has the frequency response H( jw) =24t4tWhat is the output of S when the input is x( t) e −−= u( t) − te u( t )?−2t −4t ( a) ( 0.5e −0.5e ) u( t) −2t −4t( b) ( e −0.5e ) u( t)−2t −4t ( c) ( 0.5e −e ) u( t) −4t −4t( d) ( 0.5e −e ) u( t)Q2. Consider an LTI system whose response to the input−t −3t −t −4tx( t) = ⎡⎣e + e ⎤⎦u( t) is y( t) = ⎡⎣2e −2e ⎤⎦u( t ).Find the frequency response of this system.1 3 3 3( a) + ( b)+( 4+ jω ) ( 2+ jω ) 2( 4+ jω ) 2( 2+ jω)3 3 1 3c + d +4+ jω 2 2+ jω 4+ jω 2 2+ jω( ) ( ) ( )( ) ( ) ( )Q3. The procedure for interpolation or up sampling by an integer factor N canbe thought of as the cascade of two operations. The first operation,involving system A, corresponds to inserting N-1 zero-sequence valuesbetween each sequence value of x[n], so that⎧ ⎡n⎤⎪x d ⎢ ⎥, n = 0, ± N, ± 2N, ...xp⎡⎣n⎤⎦= ⎨ ⎣N⎦⎪⎩ 0,otherwisejFor exact band – limited interpolation, He ( ω)Determine whether or not system A is:(a) Linear(c) Linear at some points, otherwise non-linearis an ideal lowpass filter.(b) Non linear(d) Can’t sayQ4. A signal x(t) with Fourier transform X(jω) undergoes impulse – trainsampling to generatep∞( ) = ∑ ( ) δ( − )x t x nT t nTn =−∞where T = 10−4If X( jω ) = 0 for ω > 5000π does the sampling theorem guarantee that x(t) canbe recovered exactly from xp( t ) ?(a) Yes(c) Some part of signal can be recovered exactly(b) No(d) Data insufficient.Q5. The following is known about a discrete – time LTI system with input x[n]and output y[n]:(1) If x[n] = ( − 2) nfor all n, then y[n] = 0 for all n.www.iesacademy.com Email: iesacademy@yahoo.com Page-2__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010ET (Paper-I)(2) If x[n] = U( n)n⎛1⎞⎜2⎟⎝ ⎠⎛1⎞y[n] =δ ⎡⎣n ⎤⎦+a ⎜ u[n]4⎟⎝ ⎠nfor all n, then y[n] for all n is of the formwhere a is a constant.Determine the value of the constant a.1 3 7( a) ( b) ( c) ( d)None of them8 8 8Q6. The autocorrelation function of a sinusoid cos (wt) is given by(a) cos(wt) (b) 2 cos(wt) (c) 1/2 cos(wt) (d) noneQ7. The energy of the signal 2e-t/2u(t) is given by(a) 2 (b) Infinite (c) 3 (d) 4Q8. A random process is called ergodic if(a) It is ergodic in mean(c) It is ergodic in mean & autocorrelation(b) It is ergodic in autocorrelation(d) NoneQ9. If x(t) has fundamental period T, x(3t – 1) has fundamental period of …..?(a) T (b) T/2 (c) T/3 (d) Can’t be determinedQ10. We are given the following 5 facts about a discrete time singnal x[n] with Z –transform X(z):(a) x[n] is real and right sided.(b) X(z) has exactly 2 poles.(c) X(z) has 2 zeroes at the origin.π1 j(d) X(z) has a pole at z = e 32(e) X(1) = 8 3Determine X(z)2 2 2 2Z 2Z 2Z Z( a) ( b) ( c) ( d)2 Z 1 2 Z 1 2 Z 1 2 Z 1Z − + Z − + Z − + Z − +4 2 4 2 2 4 2 4⎛1⎞Q11. Determine the z-transform for ⎜ un ⎡ + 3⎤2⎟ ⎣ ⎦⎝ ⎠3 3 3 32z 4z 6z 8z( a) ( b) ( c) ( d)8−z 8−z 2−z 2−zn+1−1 −1 −1 −1Q12. Indicate the region of convergence of Z-transform of⎛1⎞⎜3⎟⎝ ⎠n−2un ⎡⎣− 2⎤⎦www.iesacademy.com Email: iesacademy@yahoo.com Page-3__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-20101 1 1a 0 < z < b z < c < z < 1 d z > 14 4 4( ) ( ) ( ) ( )ET (Paper-I)Q13. A pressure gauge that can be modeled as an LTI system has a time response−t−tto a unit step input given by (1 −e − te )u(t) . For the certain input x(t), the−t−3toutput is observed to be ( 2− 3e + e ) u(t). For this observed measurement,determine the true pressure input to the gauge as a function of time.−3t −3t −3t t −3t ta 2e + 4 u(t) b 4e + 2 u(t) c 2e + 4e u(t) d 4e + 2e u(t)www.iesacademy.com Email: iesacademy@yahoo.com Page-4__( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )Q14. The signal y(t) is obtained by convolving signals x1( t) and x2( t ) where:X1( ω ) = 0 for ω > 1000 π &X ( ω ) = 0 for ω > 2000π2Impulse train sampling is performed on y(t) to get yp( t) = ∑ y( nT) δ( t−nT).−∞Specify the range of values of T so that y(t) may be recovered from yp(t).3 2a T 1 sec b T 0.5 sec c T 10 −−< < < sec d T < 10 sec( ) ( ) ( ) ( )Q15. Metal when compared to non-metals(a) Are less electronegative & have smaller atomic radii.(b) Have greater ionization energies & smaller atomic radii.(c) Are less electronegative & have larger atomic radii.(d) Have less ionization energies & smaller atomic radii.Q16. A semiconductor strain gauge has the advantage over the normal straingauge that(a) It is more linear(b) It has excellent hysteresis characteristics(c) Its low cost(d) All the aboveQ17. The gauge factor of strain gauge is 2, stress is 1050 kg/cm 2 , Y = 2.1 × 10 6 kg/cm 2 and change in resistance is 1Ω. Find the value of resistance.(a) 2000Ω (b) 1500Ω (c) 1000Ω (d) 2500ΩQ18. Which one of the following is used for the measurement of loss angle in adielectric?(a) Schering bridge (b) Megger (c) Spectrum Analyser (d) NoneQ19. A capacitive transducer has two plates of area 5 cm 2 each separated by anair gap. The displacement sensitivity due to air gap is 11.06 pF/cm. Find theair gap.(a) 2mm (b) 4 mm (c) 4.5 mm (d) 5.1 mmQ20. A Hall-effect transducer with Hall-coefficient, K = -1 × 10 -8 is required tomeasure a magnetic field of 10,000 gauss. A 2 mm bismuth slab is used as thetransducer with a current I. The output voltage of the transducer is−51.5 × 10 V. Find I.(a) 1A (b) 2A (c) 2.7 A (d) 3A25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290∞

India’s No 1IES AcademyIES-2010ET (Paper-I)Q21. A linear discrete – time system has the characteristic equation,3Z − 0.64z = 0. The system iswww.iesacademy.com Email: iesacademy@yahoo.com Page-5__(a) Stable (b) Marginally (c) unstable (d) can’t be determinedQ22. Match List – I (Materials) with List – II (Applications of materials) & selectthe correct answer given below:List – IList - II(A) AL2O3(1) LASER(B) Ruby(2) HIGH VALUE CAPACITOR(C) BaTiO3(3) FERRIMAGNETIC(D) YIG(4) INSULATORCodes:A B C D A B C D(a) 4 1 2 3 (b) 4 2 1 3(c) 1 4 2 3 (d) 1 4 3 2Q23. A 0 to 200V dc moving coil voltmeter has a guaranteed accuracy of 0.5% offull – scale reading. The voltage measured by instrument is 100 V. What isthe limiting error?(a) 0.5% (b) 1% (c) 1.5% (d) 2.5%Q24. A variable reluctance type tachometer has 135 teeth on the rotor. Thecounter records 27,000 pulses per second. The rotational speed is:(a) 3000 rpm (b) 12,000 rpm (c) 17,000 rpm (d) NoneQ25. Assertion (A): Isotopes have different atomic no.s and the same atomicmasses.Reason (R): The difference in composition between isotopes is in the no. ofneutrons in the nucleus.(a) Both A and R are true and R is the correct explanation of A(b) Both A and R are true but R is NOT the correct explanation of A(c) A is true but R is false(d) A is false but R is trueQ26. Assertion (A): In two wattmeter method, when the readings of the two wattmetersare equal but of opposite sign, p.f is zero.Reason (R): Two – watt meter method, is used only for star – connectedthree – phase circuits.(a) Both A and R are true and R is the correct explanation of A(b) Both A and R are true but R is NOT the correct explanation of A(c) A is true but R is false(d) A is false but R is trueQ27. Assertion (A): In an electromagnetic flow meter, a non – magnetic & non –conducting pipe is used for measuring the flow of fluid of low conductivity.Reason (R): The meter calibration is un-affected as the viscosity of the fluidchanges.(a) Both A and R are true and R is the correct explanation of A(b) Both A and R are true but R is NOT the correct explanation of A25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES Academy(c) A is true but R is false(d) A is false but R is trueIES-2010ET (Paper-I)Q28. Assertion (A): Capacitive transducers have a good frequency response &show non – linear behavior.Reason (R): Capacitive transducers show edge effects.(a) Both A and R are true and R is the correct explanation of A(b) Both A and R are true but R is NOT the correct explanation of A(c) A is true but R is false(d) A is false but R is trueQ29. Assertion (A): A step function voltage is applied to an RLC series circuithaving R = 2Ω, L = 1H & C = 1F.Reason (R): The transient current response of the circuit is criticallydamped.(a) Both A and R are true and R is the correct explanation of A(b) Both A and R are true but R is NOT the correct explanation of A(c) A is true but R is false(d) A is false but R is trueQ30. Assertion (A): Moving iron instrument has an unpolarised meter with twoiron vanes.Reason (R): Iron vane placed in the magnetic field gets magnetized in thedirection of current through electromagnet.(a) Both A and R are true and R is the correct explanation of A(b) Both A and R are true but R is NOT the correct explanation of A(c) A is true but R is false(d) A is false but R is trueQ31. Assertion (A): Potentiometer method of dc voltage measurement is accurate.Reason (R): Potentiometer method uses zero centre galvanometer.(a) Both A and R are true and R is the correct explanation of A(b) Both A and R are true but R is NOT the correct explanation of A(c) A is true but R is false(d) A is false but R is trueQ32. Assertion (A): A dual trace oscilloscope offers two modes, chop & alternate.Reason (R): Alternate mode can be used for displaying two waveforms ofone low frequency & other high frequency.(a) Both A and R are true and R is the correct explanation of A(b) Both A and R are true but R is NOT the correct explanation of A(c) A is true but R is false(d) A is false but R is trueQ33. Assertion (A): The conductivity of Ge is higher than that of Si.Reason (R): Mobility of charge carriers is better in Ge.(a) Both A and R are true and R is the correct explanation of A(b) Both A and R are true but R is NOT the correct explanation of A(c) A is true but R is false(d) A is false but R is truewww.iesacademy.com Email: iesacademy@yahoo.com Page-6__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010ET (Paper-I)Q34. Assertion (A): For high ‘Q’ circuits, the poles of Y(s) must lie close to the w-axis in the complex frequency plane.Reason (R): Q is inversely proportional to damping factor ξ .(a) Both A and R are true and R is the correct explanation of A(b) Both A and R are true but R is NOT the correct explanation of A(c) A is true but R is false(d) A is false but R is trueQ35. The v-i characteristics as seen from the terminal – pair (A, B) of the networkof Figure (a) is shown in Figure (b). If an inductance of value 6 mH isconnected across the terminal – pair (A, B), the time constant of the systemwill be(a) 3 μsec(b) 12 sec(c) 32 sec(d) Unknown, unless the actual network is specifiedQ36. The unit impulse response of a system is given as c(t) = - 4e -t + 6 e -2t . The stepresponse of the same system for t ≥ 0 is equal to−2t −t −2t −t( a) − 3e + 4e + 1 ( b)− 3e + 4e −1−2t −t −2t −tc −3e −4e − 1 d 3e + 4e −1www.iesacademy.com Email: iesacademy@yahoo.com Page-7__( ) ( )Q37. A coil (which can be modeled as a series – RL circuit) has been designed forhigh Q performance at a rated voltage and a specified frequency. If thefrequency of operation is doubled, and the coil is operated at the samerated voltage, then the Q-factor and the active power P consumed by thecoil will be affected as follows:(a) P is doubled, Q is halved(b) P is halved, Q is doubled(c) P remains constant, Q is doubled (d) P decreases 4 times, Q is doubledQ38. An ideal voltage source will charge an ideal capacitor(a) In infinite time(b) Exponentially(c) Instantaneously(d) None of the aboveQ39. Energy stored in a capacitor over a cycle, when excited by an a.c. source is(a) The same as that due to a d.c. source of equivalent magnitude(b) Half of that due to a d.c source of equivalent magnitude(c) Zero(d) None of the above25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010ET (Paper-I)Q40. For the circuit shown in Figure, the Norton equivalent source current valueis ............ and its resistance is............(a) 2 A, 4.5 Ω(b) 4.5 A, 2 Ω(c) 2 A, 4 Ω(d) 4 A, 2 ΩQ41. A 10 V battery with an internal resistance of 1 Ω is connected across a nonlinearload whose V - I characteristic is given by 7I = V 2 + 2V. The currentdelivered by the battery is ………… A.(a) 24 (b) 5 (c) 24.5 (d) 5.24Q42. The voltage and current waveforms for an element are shown in Figure.The circuit element is ……… and its value is ……….(a) Inductor, 2H(c) Both inductor (2H) and capacitor (2F)(b) Capacitor, 2F(d) NoneQ43. Consider a DC voltage source connected to a series R-C circuit. When thesteady-state reaches, the ratio of the energy stored in the capacitor to thetotal energy supplied by the voltage source, is equal to(a) 0.362 (b) 0.500 (c) 0.632 (d) 1.000Q44. Two 2 H inductance coils are connected in series and are also magneticallycoupled to each other-the coefficient of coupling being 0.1. The totalinductance of the combination can be(a) 0.4 H (b) 3.2 H (c) 4.0 H (d) 4.4 HQ45. The RMS value of a rectangular wave of period T, having a value of + V for aduration, T1 (

India’s No 1IES AcademyIES-2010ET (Paper-I)Q48. In the circuit shown in Figures (a) - (c), assuming initial voltages acrosscapacitors and currents through the inductors to be zero, at the time ofswitching (t = 0), then at any time t > 0, match List-I & List-II(1) Current increases monotonicallywith time(2) Current decreases monotonicallywith time(3) Current remains constant at V/R(a) (A) – (1) (B) – (2) (C) – (4)(b) (A) – (2) (B) – (3) (C) – (4)(c) (A) – (1) (B) – (3) (C) – (4)(d) (A) – (3) (B) – (2) (C) – (1)(4) Current first increases, thendecreases(5) No current can ever flowQ49. The current i4 in the circuit of Figure is equal to(a) 12 A(b) – 12 A(c) 4 A(d) None of the aboveQ50. The voltage V in Figure is equal to(a) 3 V(b) – 3 V(c) 5 V(d) None of the abovewww.iesacademy.com Email: iesacademy@yahoo.com Page-9__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010Q51. The voltage V in Figure is always equal toET (Paper-I)(a) 9 V(b) 5 V(c) 1 V(d) None of the aboveQ52. In the circuit of Figure, the energy absorbed by the 4 Ω resistor in the timeinterval (0, ∞) is(a) 36 joules(b) 16 joules(c) 256 joules(d) None of the aboveQ53. In the circuit of Figure, the equivalent impedance seen across terminals a, bis(a) (16/3) Ω(b) (8/3) Ω(c) (8/3 + 12j) Ω(d) None of the aboveQ54. In the circuit of Figure, the current i Dthrough the ideal diode (zero cut involtage and zero forward resistance) equals(a) 0 A(b) 4 A(c) 1 A(d) None of the aboveQ55. The Hall angle θ of a metal sample is(a) Independent of the magnetic flux density B(b) Independent of the carrier mobility(c) Independent of the density of free carriers(d) Dependent on magnetic flux density, carrier mobility and density of free carriersQ56. The relaxation time (τ) in a perfect dielectric is(a) 0 (b) 1 (c) 1< τ < ∞ (d) ∞Q57. The conductivity of a metal at ultraviolet frequency (10 14 Hz) approximatelyequals(a) Infinity (b) Zero (c) DC conductivity (d) Half of DC conductivitywww.iesacademy.com Email: iesacademy@yahoo.com Page-10__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010Q58. Constantan is an alloy composed of(a) 86% copper, 12% manganese and 2% nickel(b) 76% nickel, 21% chromium, 2% manganese and 1% iron(c) 60% copper and 40% nickel(d) 40% copper, 40% nickel and 20% carbonET (Paper-I)Q59. Assuming carrier mobility to be temperature independent, it can be shownthat pure Si(Eg = 1.1eV) and Ge (Eg = 0.7eV) have the same conductivity at atemperature of(a) 191 K (b) 300 K (c) 471 K (d) 1470 KQ60. If the lattice temperature is increased then the Hall coefficient of asemiconductor will(a) Decrease(b) Increase(c) First increase to a peak and then decrease (d) Remain constantQ61. The decreasing order of the electrical resistivities of nichrome, silicon anddiamond is(a) Nichrome, silicon, diamond (b) Silicon, diamond, nichrome(c) Diamond, nichrome, silicon (d) Diamond, silicon, nichromeQ62. An n-channel silicon (Eg = 1.1 eV) MOSFET was fabricated using n + polysilicongate and the threshold voltage was found to be 1 V. Now, if the gateis changed to p + poly-silicon, other things remaining the same, the newthreshold voltage should be(a) -0.1 V (b) 0 V (c) 1.0 V (d) 2.1VQ63. A silicon nMOSFET has a threshold voltage of 1 V and oxide thickness ofo400 A [εr(SiO2) = 3.9, εo = 8.854 × 10 -14 F/cm, q = 1.6 × 10 -19 C]. The regionunder the gate is ion implanted for threshold voltage tailoring. The doseand type of the implant (assumed to be a sheet charge at the interface)required shifting the threshold voltage to - 1 V are(a) 1.08 × 10 12 /cm 2 , p – type(b) 1.08 × 10 12 /cm 2 , n – type(c) 5.4 × 10 11 /cm 2 , p – type(d) 5.4 × 10 11 /cm 2 , n –typeQ64. A Zener diode in the circuit shown in Figure has a knee current of 5 mA,and a maximum allowed power dissipation of 300 mW. What are theminimum and maximum load currents that can be drawn safely from thecircuit, keeping the output voltage Vo constant at 6 V?(a) 0 mA, 180 mA(b) 5 mA, 110 mA(c) 10 mA, 55 mA(d) 60 mA, 180 mAQ65. 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 fieldwww.iesacademy.com Email: iesacademy@yahoo.com Page-11__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010ET (Paper-I)(c) Increases at low values of electric field and decreases at high values of electricfield exhibiting negative differential resistance(d) Increases linearly with electric field at low values of electric field and graduallysaturates at higher values of electric fieldQ66. The diffusion potential across a P-N 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 concentrationQ67. The break down voltage of a transistor with its base open is BVCEO and thatwith emitter open is BVCBO, then(a) BVCEO = BVCBO(b) BVCEO > BVCBO(c) BVCEO < BVCBO(d) BVCEO is not related to BVCBO.Q68. In a P type silicon sample, the hole concentration is 2.25 × 10 15 /cm 3 . If theintrinsic carrier concentration is 1.5 × 10 10 /cm 3 , the electron concentrationis(a) zero (b) 10 10 /cm 3 (c) 10 5 /cm 3 (d) 1.5 × 10 25 /cm 3Q69. In the transistor circuit shown in Figure below, collector-to-ground voltageis + 20 V. Which of the following is the probable cause of error?(a) Collector-emitter terminals shorted(b) Emitter to ground connection open(c) 10 kΩ resistor open(d) Collector-base terminals shortedQ70. The static characteristic of an adequately forward biased p-n junction is astraight line, if the plot is of(a) log I vs. log V (b) log I vs. V (c) I vs. log V (d) I vs. VQ71. For a MOS capacitor fabricated on a p-type semiconductor, strong inversionoccurs when(a) Surface potential is equal to Fermi potential(b) Surface potential is zero(c) Surface potential is negative and equal to Fermi potential in magnitude(d) Surface potential is positive and equal to twice the Fermi potential.Q72. The probability that an electron in a metal occupies the Fermi-level, at anytemperature (> 0 K)(a) 0 (b) 1 (c) 0.5 (d) 1.5www.iesacademy.com Email: iesacademy@yahoo.com Page-12__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010ET (Paper-I)Q73. A transistor having α = 0.99 and VBE= 0.7 V is used in the circuit shownin Figure. The value of the collectorcurrent will be .(a) 1.39 mA (b) 3.7 mA(c) 5.33 mA (d) 7.73 mAQ74. An n-p-n transistor under forward-active mode of operation is biased at IC =1 mA, and has a total emitter-base capacitance C π of 12 pF, and the basetransit time τ Fof 260 psec. Under this condition, the depletion capacitanceof the emitter-base junction is .[use VT. 26mV](a) 2pF (b) 3pF (c) 4pF (d) 6pFQ75. The units of q/kT are(a) V(b)1V − (c) J (d) J/KQ76. An n channel JFET has IDSS = 1 mA and Vp = -5 V. The maximum transconductanceis .(a)0.2m (b)0.4m (c)0.6m (a)0.8mQ77. The three values of a one-dimensional potential function φ shown in the givenFigure and satisfying Laplace equation are related aswww.iesacademy.com Email: iesacademy@yahoo.com Page-13__2φ + φ 2φ + φ 2φ + 2φ φ + 3φφ = φ = φ = φ =3 3 3 2( a) ( b) ( c) ( d)3 1 1 3 1 3 1 32 2 2 2Q78. The electric field of a uniformplane wave is givenby8E = 10cos( 3π×10 t−πz)axMatch List I with List II pertaining to the above wave and select the correctanswer using the codes given below the lists:List IList II(Parameters)(Values in MKS units)A. Phase velocity 1. 2B. Wavelength 2. 3.14C. Frequency 3. 377D. Phase constant 4. 1.5 × 10 85. 3.0 × 10 8Codes:A B C D A B C D25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010(a) 5 4 3 2 (b) 3 4 2 1(c) 4 3 1 2 (d) 5 1 4 2ET (Paper-I)Q79. A loss less long transmission line charged to a voltage V and a capacitor Ccharged to a voltage V/2 are shown in the given Figure. If the switch isclosed at t = 0, the voltage V(t) across the capacitor for t ≥ 0 is given byttV⎛ − ⎞CZV⎛ − ⎞0 CZ0( a) V( t) = 1− e ( b) V( t)= 2−e2 ⎜ ⎟ 2 ⎜ ⎟⎝ ⎠ ⎝ ⎠t⎛ − ⎞CZ0( c) V( t) = 2− e ( d) V( t)= V,t > 0⎜ ⎟⎝ ⎠3V= ,t = 04Q80. Two vectors A and B are such that A + B = nA, where n is a positive scalar< 1. The angle between A and B isπ3π( a) ( b) ( c) π( d)2π2 4Q81. A lossless 50 Ω transmission line is terminated in (A) 25 Ω and (B) 100 Ωloads. Which one of the following statements would be correct, if the voltagestanding wave patterns measured in the two cases are compared?(a) The two patterns will be identical in all respects and cannot be distinguished.(b) The two patterns will have identical locations of maxima/minima but the VSWRwill be higher in the case of A.(c) The two patterns will have identical locations of maxima/minima but the VSWRwill be higher in the case of B.(d) The two patterns will be identical except for a relative spatial shift of quarterwavelength in the two cases.Q82. When the polarisation of the receiving antenna is unknown, to ensure thatit receives at least half the power (except in one particular situation), thetransmitted wave should be(a) Horizontally polarised(b) Vertically polarised(c) Circularly polarised(d) Elliptically polarisedQ83. A parabolic dish has a diameter of 10 m. The maximum possible (ideal) gainof the antenna at λ = 3.14 cm will be(a) 30 dB (b) 40 dB (c) 50 dB (d) 60 dBwww.iesacademy.com Email: iesacademy@yahoo.com Page-14__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010ET (Paper-I)Q84. The arrangement for calibrating a phase shifter is shown in the followingdiagram:The calibrated short is adjusted while phase shift is introduced by thephase shifter under test to maintain a null at the probe fixed in location. Inone such measurement, the displacement of the short is 5 mm while theguide wavelength in it is 5 cm. At this setting of the phase shifter, the valueof the phase shift (in degrees) will be(a) 90 (b) 72 (c) 45 (d) 36Q85. For time-varying electromagnetic fields with electric and magnetic fieldgiven by E and H respectively, the rate of energy flow per unit area has amagnitude given by( a) E H cos θ ( b) E H sin θ ( c) ( E + H) sin θ ( d) ( E − H)cos θ85.Q86. Consider the components of E and H listed below:1. Ex 2. Ey 3. Ez 4. Hy 5.HzFor a plane wave traveling in x-direction and linearly polarized in y-direction(a) 1, 2 and 5 exist(b) 1, 3 and 4 exist(c) 3 and 4 exist(d) 2 and 5 exist8Q87. The expression for B , given that in free space ( )www.iesacademy.com Email: iesacademy@yahoo.com Page-15__is−8 8( a) 5× 10 cos ( 6π× 10 t −2πz)iy8 8( b) −90π× 10 sin ( 6π× 10 t−2πz)ix8 8( c) − 45× 10 sin ( 6π× 10 t−2πz)iy−8 8( ) × ⎡ ( π× − π ) − ( π×8− π )d 5 10 cos 6 10 t 2 z i sin 6 10 t 2 z iz⎤⎣⎦E = 15cos 6π× 10 t−2π z ix V/mQ88. A wave is propagated in a parallel-plane wave-guide. The frequency is 6GHz and plane separation is 3 cm. For the dominant mode match List I withList II and select the correct answer using the codes given below the lists:List IList II(Quantities)(Numerical values)A. Cut-off wavelength (cm) 1. 5B. Wavelength in wave guide (cm) 2. 6C. Phase velocity (megametre/sec) 3. 9.0525, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010D. Group velocity (megametre/sec) 4. 166Codes 5. 543A B C D A B C D(a) 1 2 5 4 (b) 2 1 4 3(c) 2 1 5 4 (d) 5 4 2 3ET (Paper-I)Q89. A transmission line of 50 Ω characteristic impedance is terminated with a100 Ω resistance. The minimum impedance measured on the line is equal to(a) 0 Ω (b) 25 Ω (c) 50 Ω (d) 100 ΩQ90. A parabolic dish antenna has a conical beam 2° wide. The directivity of theantenna is approximately(a) 20 dB (b) 30 dB (c) 40 dB (d) 50 dBQ91. The skin depth at 10 MHz for a conductor is 1 cm. The phase velocity of anelectromagnetic wave in the conductor at 1000 MHz is abouta 6× 10 6 m/s b 6× 10 7 m/s c 3× 10 8 m/s d 6×10 8 m/s( ) ( ) ( ) ( )Q92. The intrinsic impedance of copper at high frequencies is(a) Purely resistive(b) Purely inductive(c) Complex with a capacitive component(d) Complex with an inductive componentQ93. All transmission line sections in Figure have a characteristic impedance R0+ j0. The input impedance Zin equals2 3a R b R c R d 2R3 2( ) ( ) ( ) ( )0 0 0 0Q94.The time averaged Poynting vector, in W/m 2 j( ωt+ βz), for a wave with E = 24e ayV/m in free space isz z ( c) 4.8 z ( d)−4.8zπ π π π( ) a − a ( b) 2.4 aaaQ95. The wavelength of a wave with propagation constant (0.1 π + j 0.2 π) m -1 is( a) 2m0.05( b10m ) ( c) 20m ( d)30mwww.iesacademy.com Email: iesacademy@yahoo.com Page-16__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010ET (Paper-I)Q96. The depth of penetration of a wave in a lossy dielectric increases withincreasing(a) Conductivity(b) Permeability(c) Wavelength(d) Permittivityj t zQ97. The polarisation of a wave with electric field vector E E e ω − β= a x + awww.iesacademy.com Email: iesacademy@yahoo.com Page-17__(a) Linear(c) Left hand circular(b) Elliptical(d) Right hand circular( )( y)Q98. The radiation resistance of a circular loop of one turn is 0.01 Ω. Theradiation resistance of five turns of such a loop will be(a) 0.002 Ω (b) 0.01 Ω (c) 0.05 Ω (d) 0.25 ΩQ99. An antenna in free space receives 2 μW of power when the incident electricfield is 20 mV/m rms. The effective aperture of the antenna is(a) 0.005 m 2 (b) 0.05 m 2 (c) 1.885 m 2 (d) 3.77 m 2Q100. The maximum usable frequency of an ionospheric layer at 60° incidenceand with 8 MHz critical frequency is(a) 16 MHz(b) 16 MHz3(c) 8 MHz25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 98109582900(d) about 6.93 MHzQ101. Bond strength of secondary bonds is in the range of(a) 1 kJ/mol (b) 10 kJ/mol (c) 100 kJ/mol (d) 1000 kJ/molQ102. Electron sea exists in(a) Polar bonds (b) Ionic bond (c) Covalent bond (d) Metallic bondQ103. Coordination number for closest packed crystal structure(a) 16 (b) 12 (c) 8 (d) 4Q104. Pick the thermo-plast from the following(a) Vinyls (b) Epoxies (c) Resins (d) Vulcanized rubberQ105. Schottky-defect in ceramic material is(a) Interstitial impurity(b) Vacancy- interstitial pair of cations(c) Pair of nearby cation and anion vacancies (d) Substitutional impurityQ106. Basic source of magnetism ______________.(a) Charged particles alone(b) Movement of charged particles(c) Magnetic dipoles(d) Magnetic domainsQ107. Match list-1 with list-2:List-1List-21. Dia-magnetic (A) superconductors2. Para-magnetic (B) alkali metals3. Ferro-magnetic (C) transition metalsis

India’s No 1IES AcademyIES-20104. Ferri-magnetic (D) ferrite(a) A-1,B-2,C-3,D-4(b)A-1,B-2,C-4,D-3(c) A-2,B-1,C-3,D-4(d)A-2,B-1,C-4,D-3Q108. Magnetic susceptibility ferro-magnetic materials is(a) +10 −5 (b) -10 −5 (c) 10 5 (d) 10 −5 to 10 −2Q109. Typical size of magnetic domains ______ (mm).(a) 1-10 (b) 0.1-1 (c) 0.05 (d) 0.001Q110. Which one of the following is soft magnet?(a) 45 Permalloy (b) CrO2 (c) Fe-Pd (d) AlnicoQ111. Example for magnetic material used in data storage devices(a) 45 Permalloy (b) CrO2 (c) Cunife (d) AlnicoET (Paper-I)Q112. Flow of electrons is affected by the following(a) Thermal vibrations (b) Impurity atoms (c) Crystal defects (d) allQ113. Fermi energy level for p-type extrinsic semiconductors lies(a) At middle of the band gap (b) Close to conduction band(c) Close to valence band(d) NoneQ114. Fermi level for extrinsic semiconductor depends on(a) Donor element (b) Impurity concentration (c) Temperature (d) AllQ115. High dielectric constant material is must for __________.(a) Insulation of wires(b) Generators(c) Switch bases(d) Generators.Q116. Dielectric constant for most polymers lies in the range of _______.(a) 1-3 (b) 2-5 (c) 4-7 (d) 6-10.Q117. Example for piezo-electric material(a) Rochelle salt(b) Lead zirconate(c) Potassium niobate (d) Barium Titanium oxideQ118. The angle between [111] and [11−2] directions in a cubic crystal is (indegrees)(a) 0 (b) 45 (c) 90 (d) 180Q119. Miller indices of the line of intersection of (−1−11) and (110) are(a) [110] (b) [101] (c) [10−1] (d) [−110]Q120. Copper behaves as a:(a) Conductor always(b) Conductor or dielectric depending on the applied electric field strength(c) Conductor or dielectric depending on the frequency(d) Conductor or dielectric depending on the electric current densitywww.iesacademy.com Email: iesacademy@yahoo.com Page-18__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010ET (Paper-I)1. Ans. (a)2. Ans. (b)3. Ans. (a)4. Ans. (a)5. Ans. (d)6. Ans. (c)7. Ans. (d)8. Ans. (c)9. Ans. (c)10. Ans. (c)11. Ans. (d)12. Ans. (a)13. Ans. (b)14. Ans. (c)15. Ans. (c)16. Ans. (b)17. Ans. (c)18. Ans. (a)19. Ans. (a)20. Ans. (d)21. Ans. (a)22. Ans. (a)23. Ans. (b)24. Ans. (b)25. Ans. (d)26. Ans. (c)27. Ans. (b)28. Ans. (a)29. Ans. (a)30. Ans. (c)31. Ans. (a)32. Ans. (c)33. Ans. (a)34. Ans. (a)35. Ans. (a)36. Ans. (b)37. Ans. (d)38. Ans. (c)39. Ans. (c)40. Ans. (a)Answer41. Ans. (b)42. Ans. (a)43. Ans. (b)44. Ans. (d)45. Ans. (a)46. Ans. (a)47. Ans. (b)48. Ans. (a)49. Ans. (b)50. Ans. (a)51. Ans. (a)52. Ans. (b)53. Ans. (b)54. Ans. (c)55. Ans. (d)56. Ans. (d)57. Ans. (b)58. Ans. (c)59. Ans. (c)60. Ans. (a)61. Ans. (d)62. Ans. (c)63. Ans. (a)64. Ans. (c)65. Ans. (d66. Ans. (d)67. Ans. (c)68. Ans. (c)69. Ans. (b)70. Ans. (b)71. Ans. (d)72. Ans. (b)73. Ans. (c)74. Ans. (a)75. Ans. (b)76. Ans. (b)77. Ans. (a)78. Ans. (d)79. Ans. (a)80. Ans. (c)81. Ans. (a)82. Ans. (c)83. Ans. (d)84. Ans. (b)85. Ans. (b)86. Ans. (d)87. Ans. (a)88. Ans. (c)89. Ans. (d)90. Ans. (a)91. Ans. (a)92. Ans. (a)93. Ans. (b)94. Ans. (a)95. Ans. (b)96. Ans. (c)97. Ans. (c)98. Ans. (b)99. Ans. (c)100. Ans. (b)101. Ans. (b)102. Ans. (d)103. Ans. (b)104. Ans. (a)105. Ans. (c)106. Ans. (b)107. Ans. (a)108. Ans. (c)109. Ans. (c)110. Ans. (a)111. Ans. (b)112. Ans. (d)113. Ans. (b)114. Ans. (d)115. Ans. (a)116. Ans. (c)117. Ans. (b)118. Ans. (c)119. Ans. (d)120. Ans. (a)www.iesacademy.com Email: iesacademy@yahoo.com Page-19__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290