IES-2010 IES Academy EE (Paper-II) Electrical Engineering (Paper-II)

India’s No 1IES AcademyIES-2010EE (Paper-II)Electrical Engineering (Paper-II)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-2010EE (Paper-II)Q1. A winding is distributed in the slots along the air-gap periphery1. To add mechanical strength to the winding2. To reduce the amount of conductor material required3. To reduce the harmonics in the generated emf4. To reduce the size of the machine5. For full utilization of iron and conductor materialsFrom these, the correct answer is:(a) 1, 3, 4, 5 (d) 1, 2, 4, 5 (c) 1, 2, 3, 5 (d) 1, 3, 5Q2. A 3-phase, 4-pole alternator has 48 stator slots carrying a 3-phase distributedwinding. Each coil of the winding is short chorded by one slot pitch. Thewinding factor is given by( a) cos 7.5 ( b) cot 7.5 ( c) 1 ( d )cot 7.516 8 8 sin 7.5 16Q3. The seventh harmonic mmf wave, produced by 3-phase currents flowing in 3-phase balanced winding, rotates with respect to the fundamental field (N s =speed of fundamental mmf wave) at a speed of( a) 6 N ( ) 7 (c)8 ( d)7sb Ns Ns Ns7 6 7 8Q4. In a DC machine; Z, P, I a and a are respectively the number of conductors,number of poles, armature current and number of parallel paths. The peakvalue of fundamental component of armature mmf wave is:8 ⎡ Z Ia ⎤ 8 ⎡Z Ia ⎤ 4 ⎡ Z Ia ⎤ 8 ⎡ Z Ia⎤( a) ( b) 2( c) ( d)2π⎢ ⋅2P a⎥π⎢ ⋅P a⎥π⎢ ⋅ ⋅2P a⎥π⎢2P a⎥⎣ ⎦ ⎣ ⎦ ⎣ ⎦ ⎣ ⎦Q5. Match the items in the left-side column with the most appropriate item in theright-side column:Power lossesDependent uponA. No-load rotational loss 1. Square of loadB. Hysteresis and eddy-current losses 2. Rotor rotationC. Brush contact loss 3. Value of fluxD. Stray load loss 4. LoadQ6. In DC machines, the field system has to be provided on stator unlikesynchronous machines wherein it could be on any member, because(a) It reduces field structure iron losses(b) It gives more uniform air-gap flux distribution(c) Commutator action is not possible otherwise(d) DC machines are comparatively low rating machines.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-2010EE (Paper-II)Q7. The brush-axis of a bipolar dc motor is rotated by 90°. The effect of thisrotation on the back emf E b and the torque developed T d would be such that(a) Both E b and T d are unchanged (b) E b is zero, but T d is unchanged(c) E b is unchanged, but T d is zero (d) Both E b and T d are zeroQ8. A self-excited shunt generator fails to build up, because1. The field circuit is open 2. The armature circuit is open3. The residual magnetism is absent 4. The direction of rotation is wrongFrom these, the correct answer is:(a) 3 only (b) 1, 3 (c) 1, 2, 3 and 4 (d) 1, 2 and 3Q9. A separately-excited dc generator, running at rated speed, has 6 volts acrossits armature terminals with no field current. When field winding is excitedwith one ampere, the voltage builds up to 250 V at no load. In case fieldcurrent is reduced to zero, with the speed remaining unaltered, the armatureterminal voltage would be:(a) 6 V (b) Less than 6 V (c) More than 6 V (d) ZeroQ10. A separately-excited dc motor has an armature resistance of 0.5 Ω. It runsoff a 250 V DC supply drawing an armature current of 20 A at 1500 rpm.The torque developed for an armature current of 10 A, for the same fieldcurrent, will be:(a) 15.28 Nm (b) 15.92 Nm (c) 15.6 Nm (d) 16.55 NmQ11. Which of the following factors improve commutation in a DC machine?1. High contact resistance of brushes2. High inductance of the coils undergoing commutation3. Shifting of brushes in the direction of rotation for a generator and inthe opposite direction for a motor4. Narrow width for the commutation bars.Select the correct answer using the codes given below:Codes:(a) 1, 2, and 3 (b) 1 and 3 (c) 2, 3 and 4 (d) 1, 2 and 4Q12. A DC shunt generator has full-load voltage regulation of 10% at rated speedof 1000 rpm. If it is now driven at 1250 rpm, then its voltage regulation at fullload would(a) Be more than 10% (b) Be less than 10%(c) Remain unchanged (d) Be 12.5%Q13. A DC cumulatively compounded motor delivers rated load torque at rated speed.If the series field is short-circuited, then the armature current and speed will(a) Both increase(b) Both deceasewww.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-2010(c) Increase and decrease respectivelyEE (Paper-II)(d) Decrease and increase respectively.Q14. A 200 V DC shunt motor delivers an output of 17 kW with an input of 20kW. The field winding resistance is 50 Ω and the armature-circuit resistanceis 0.04 Ω. Maximum efficiency will be obtained when total armature ohmiclosses are equal to(a) 2632 W (b) 3000 W (c) 3680 W (d) 5232 WQ15. In a synchronous generator operating at zero power factor lagging, the effectof armature reaction is:(a) Magnetizing(b) Demagnetizing(c) Cross-magnetizing(d) Both magnetizing and cross-magnetizingQ16. Read the following statements about a cylindrical-rotor alternator:1. Armature reaction mmf due to 0.8 lagging pf current is partly crossmagnetizingand partly demagnetizing2. The field poles lead the resultant air-gap flux3. The field poles have a tendency to go away from the resultant air-gapflux4. Terminal voltage lags the field flux by 90 + δ.From these, the correct answer is(a) 1, 2, 4 (b) 1, 2, 3, 4 (c) 2, 3, 4 (d) 1, 3, 4Q17. A cylindrical-rotor synchronous generator will deliver maximum poweroutput when(a) Load angle = synchronous impedance angle(b) Load angle = internal power-factor angle(c) Load angle = 90°(d) Input power factor is unity.Q18. In Fig. C.68, the characteristicthat corresponds to the variationof synchronous reactance of asynchronous machine with thefield current is:(a) Curve A (b) Curve B(c) Curve C (d) Curve Dwww.iesacademy.com Email: iesacademy@yahoo.com Page-4__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010EE (Paper-II)Q19. A 3-phase synchronous generator, with negligible armature resistance,operates at a lagging pf and delivers constant power to an infinite bus. If itsexcitation is increased, then (δ = power angle and cos θ = power factor)(a) 8 decreases and cos θ tends to become unity(b) 8 decreases and cos θ tends to become more lagging(c) 8 increases and cos θ tends to become unity(d) 8 increases and cos θ tends to become more laggingQ20. A cylindrical-rotor synchronous motor, with negligible armature resistance,operates at1. Unity pf if E f cos 8 = V t 2. Lagging pf if E f cos 8 > V t3. Lagging pf if E f cos 8 < V t 4. Zero pf leading if Ef > V t5. Zero pf lagging if E f > V tFrom these, the correct answer is:(a) 1,3,4 (b) 1, 2, 4 (c) 1, 3, 5 (d) 1, 2, 5Q21. A synchronous machine is operating at constant load and at unity powerfactor. If its excitation is increased, then it operates as1. A generator at a leading pf 2. A motor at a leading pf3. A generator at a lagging pf 4. A motor at a lagging pf5. Exporter of reactive power 6. Absorber of reactive powerFrom these, the correct answer is:(a) 2, 4, 6 (b) 1, 2, 5 (c) 2, 3, 5 (d) 3, 4, 6Q22. A 3-phase overexcited synchronous motor is installed near a 3-phaseinduction motor (IM) with a view to improve the power factor. With thisinstallation,(a) IM pf improves and its current decreases(b) IM pf does not change but its current decreases(c) IM pf improves but its current does not change(d) IM pf and its current do not change, pf of the combination improves.Q23. The name plate of an alternator indicates an operating pf of 0.85. The natureof this pf is:(a) Lagging so that excitation emf E f > terminal voltage V t and alternatorabsorbs reactive power Q(b) Lagging so that E f > V t and alternator delivers Q(c) Leading so that E f < V t and alternator absorbs Q(d) Leading so that E f < V t and alternator delivers QQ24. If the rotor of a 3-phase IM is assumed purely inductive, then theelectromagnetic torque developed in the motor is:(a) Optimum with load angle δ = 0° (b) Optimum with δ = 90°www.iesacademy.com Email: iesacademy@yahoo.com Page-5__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010EE (Paper-II)www.iesacademy.com Email: iesacademy@yahoo.com Page-6__(c) Optimum with δ = 0° (d) Zero with δ = 180°Q25. A 3-phase IM connected in star takes 20 A from the supply mains. Whenconnected in delta, the motor shall take from the supply mains a current of( a) 20 3 A ( b) 20 ( c) 20A ( d ) 10A3Q26. Three-phase induction motors with open slots have1. More starting torque T est , more starting current I st and improved pf2. More T est , more I st and worsened. pf3. More T est , more breakdown torque and improved pf4. More T est , more breakdown torque and worsened pf5. More T est , more slip at which maximum torque occursFrom these, the correct answer is:(a) 1, 3 (b) 1, 3, 5 (c) 2, 4 (d) 2, 4, 5Q27. A 3-phase SRIM is fed from the rotor side with stator winding shortcircuited. The frequency of the currents flowing in the short-circuited statoris:(a) Slip frequency(b) Supply frequency(c) Zero(d) Frequency corresponding to rotor speedQ28. A 3-phase SCIM is running at slip s with synchronous speed N s clockwiseand rotor speed N r .If its two supply leads are interchanged, then at that instant1. Slip is (2 - s)2. Speed of air-gap field with respect to stator is (N s + N r ) clockwise3. Speed of air-gap field with respect to rotor is (N s + N r ) anticlockwise4. Speed of air-gap field with respect to stator is N s anticlockwise5. Effective rotor resistance increases6. Stator current decreasesFrom these, the correct answer is:(a) 1, 3, 4, 5, 6 (b) 2, 3, 4, 5, 6 (c) 1, 3, 4, 5 (d) 1, 2, 4, 5Q29. Consider the following statements regarding the equivalent circuitparameters of an IM:1. Leakage reactance is dependent on supply current2. Magnetizing reactance is dependent on the air-gap flux3. Core loss is dependent on the input voltage and frequency4. Rotor resistance is dependent on the speedOf these statements(a) 2 and 3 are correct(b) 1, 3 and 4 are correct(c) 1, 2, 3 and 4 are correct(d) 1, 2 and 4 are correct25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010EE (Paper-II)Q30. When started by means of an auto-transformer with 50% tapping, supplycurrent at start of a 3 - φ SCIM is I aut and when started by means of a stardeltastarter, the supply current at start is I y . The ratio of is:IautI(a) 1.33 (b) 0.813 (c) 1.5 (d) 0.75Q31. If the fault current is 2000 amps, the relay setting 50% and the C.T. ratio is400/5, then the plug setting multiplier will be:(a) 25 amps (b) 15 amps (c) 50 amps (d) None of the aboveQ32. The voltages at the two ends of a line are 132 kV and its reactance is 40 ohms.The capacity of the line is:(a) 435.6 MW (b) 217.5 MW (c) 251.5 MW (d) 500 MWQ33. In order to have lower cost of electrical energy generation:(a) The load factor and diversity factor should be low(b) The load factor should be low but diversity factor should be high(c) The load factor should be high but diversity factor low(d) The load factor and diversity factors should be highQ34. A Mho relay is a:(a) Voltage restrained directional relay(b) Voltage controlled over current relay(c) Directional restrained over current relay(d) Directional restrained over voltage relayQ35. Ferranti effect on long overhead lines is experienced when it is:(a) Lightly loaded(b) On full load at unity p.f.(c) On full load at 0.8 p.f. lag(d) In all these cases.Q36. If α is the angle of voltage wave at which an R-L circuit is switched in and θis the impedance angle of the R-L circuit, there will be no transient when thecircuit is switched in, if:(a) α = θ (b) α = 90 - θ (c) α = 90 + θ (d) None of the aboveyQ37. The inertia constant of two groups of machines, which swing together are M 1and M 2 . The inertia constant of the system is:MM(a)1 2M + M1 2M + M(b) M 1 - M 2, M 1 > M 2 (c) M 1 + M 2 (d)1 2MM1 2www.iesacademy.com Email: iesacademy@yahoo.com Page-7__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010EE (Paper-II)Q38. The breakdown strength of air at STP is 21 kV/cm. Its breakdown strengthat 30°C and 72 cm of Hg will be:(a) 21.25 kV/cm (b) 20.2 kV/cm (c) 23 kV (d) 19.5 kV/cmQ39. A system is said to be effectively grounded if its:(a) Neutral is grounded directly (b) Ratio of0R(c) Ratio of0X1> 2.0XXX(d) Ratio of0X11> 3.0< 3.0Q40. The capacitance of a 3-core cable between any two conductors with sheathearthed is 2 μF. The capacitance per phase will be:(a) 1 μF (b) 4 μF (c) 0.667 μF (d) 1.414 μFQ41. The magnetizing-inrush-current in a transformer is rich in:(a) 3 rd harmonics(b) 5 th harmonics(c) 7 th harmonics(d) 2 nd harmonics.Q42. With 100% series compensation of lines(a) The circuit is series resonant at power frequency(b) Low transient voltage(c) High transient current(d) (a) and (c)Q43. For any fixed degree of series compensation additional capacitive shuntcompensation(a) Increases the effective length of line(b) Increases virtual surge impedance of line(c) Decreases virtual surge impedance loading of the line(d) (b) and (c)Q44. The propagation constant of a transmission line is:0.15 × 10 -3 + j1.5 × 10 -3The wavelength of the travelling wave is:(a)15×102π−32π15×10 −(b)3(c)15×10 −3ππ15×10 −(d)3Q45. The self-inductance of a long cylindrical conductor due to its internal fluxlinkages is k H/m. If the diameter of the conductor is doubled, then the selfinductanceof the conductor due to its internal flux linkages would be:(a) 0.5 K H/m (b) K H/m (c) 1.414 K H/m (d) 4 k H/m.www.iesacademy.com Email: iesacademy@yahoo.com Page-8__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010EE (Paper-II)Q46. The equivalent Thevenin’s bus admittance matrix of a two-bus system with⎡− j30 + j10⎤identical generators on both buses is ⎢⎥ . The generator reactance⎣+ j10 −j30⎦and interconnecting line reactance will be respectively(a) j0.05 and j0.1 (b) -j0.05 and j0.1(c) -j0.05 and -j0.1(d) j0.1 and j0.05.Q47. The equivalent capacitor arrangementof two string insulator is shown in theabove figure. The maximum voltagethat each unit can withstand shouldnot exceed 17.5 kV. The line-voltage ofthe complete string is:(a) 17.5 kV (b) 33 kV(c) 35 kV(d) 37.3 kVQ48. NBFM is considered same as DSBAM. But NBFM differs in one respect withDSBAM. It is that(a) Amplitude of sidebands is different(b) There is 90° phase difference between carrier and sideband(c) Sideband frequencies are more(d) Carrier vanishes in FMQ49. Which one of the following sequences of operations represents the ratedoperating duty cycle of a circuit breaker?(O-open; C-Close; t = 3 sec., T = 3 min.)(a) O-t-CO-T-CO(b) O-CO-t-CO-T-C(c) O-C-t-OC-T(d) O-CO-T-CO-T-CQ50. If, for a given alternator in economic operation mode, the incremental cost isdPgiven by (0.012P + 8) Rs./mwh, LdP= 0.2 and plant λ = 25, then the powergeneration is:(a) 1000 MW (b) 1250 MW (c) 750 MW (d) 1500 MWQ51. If a generator of 250 MVA rating has an inertia constant of 6 MJ/MVA, itsinertia constant on 100 MVA base is:(a) 15 MJ/MVA (b) 10.5 MJ/MVA (c) 6 MJ/MVA (d) 2.4 MJ/MVAwww.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-2010EE (Paper-II)Q52. In Merz Price percentage differential protection of a Δ - Y transformer, theCT secondaries connection in the primary and secondary windings of thetransformer would be in the form of(a) Δ - Y (b) Y - Δ (c) Δ - Δ (d) Y – YQ53. A traveling wave 400/1/50 means crest value of(a) 400 V with rise time of 1/50 s(b) 400 kV with rise time 1 s and fall time 50 s(c) 400 kV with rise time 1μs and fall time 50 μs(d) 400 MV with rise time 1 μs and fall time 50 μs.Q54. A three-phase transformerhaving zero-sequenceimpedance of Z 0 has thezero-sequence network asshown in the above figure.The connections of itswindings are:(a) Star-star(c) Star-delta(b) Delta-delta(d) Delta-star with neutral groundedQ55. Assuming carrier mobility to be temperature independent, it can be shownthat pure Si (E g = 1.1eV) and Ge (E g = 0.7eV) have the same conductivity at atemperature of(a) 191 K (b) 300 K (c) 471 K (d) 1470 KQ56. 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 constantQ57. 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, nichromeQ58. An n-channel silicon (E g = 1.1 eV) MOSFET was fabricated using n + polysilicongate and the threshold voltage was found to be 1 V. Now, if the gate ischanged 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) 2.1Vwww.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-2010EE (Paper-II)Q59. A silicon nMOSFET has a threshold voltage of 1 V and oxide thickness ofoA[ε r (SiO 2 ) = 3.9, ε o = 8.854 × 10 -14 F/cm, q = 1.6 × 10 -19 C]. The400region under the gate is ion implanted for threshold voltage tailoring. Thedose and type of the implant (assumed to be a sheet charge at the interface)required to shift the threshold voltage to - 1 V are:(a) 1.08 × 10 12 /cm 2 , p – type(c) 5.4 × 10 11 /cm 2 , p – type(b) 1.08 × 10 12 /cm 2 , n – type(d) 5.4 × 10 11 /cm 2 , n –typeQ60. A Zener diode in the circuit shown in Figure has a knee current of 5 mA, anda maximum allowed power dissipation of 300 mW. What are the minimumand maximum load currents that can be drawn safely from the circuit,keeping the output voltage V o constant at 6 V?(a) 0 mA, 180 mA(b) 5 mA, 110 mA(c) 10 mA, 55 mA(d) 60 mA, 180 mAQ61. The drift velocity of electrons, in silicon,(a) Is proportional to the electric field for all values of electric field(b) Is independent of the electric field(c) Increases at low values of electric field and decreases at high values ofelectric field exhibiting negative differential resistance(d) Increases linearly with electric field at low values of electric field andgradually saturates at higher values of electric fieldQ62. 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 concentrationQ63. The break down voltage of a transistor with its base open is BV CEO and thatwith emitter open is BV CBO , then(a) BV CEO = BV CBO(b) BV CEO > BV CBO(c) BV CEO < BV CBO(d) BV CEO is not related to BV CBOwww.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-2010EE (Paper-II)Q64. 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 concentration is:(a) Zero (b) 10 10 /cm 3 (c) 10 5 /cm 3 (d) 1.5 × 10 25 /cm 3Q65. In the transistor circuit shown in Figure below, collector-to-ground voltage is+ 20 V. Which of the following is the probable cause of error?(a) Collector-emitter terminalsshorted(b) Emitter to ground connectionopen(c) 10 kΩ resistor open(d) Collector-base terminals shortedQ66. 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. VQ67. 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.Q68. The probability that an electron in a metal occupies the Fermi-level, at anytemperature (> 0 K)(a) 0 (b) 1 (c) 0.5 (d) 1.5Q69. A transistor having α = 0.99 and V BE = 0.7 V isused in the circuit shown in Figure. The valueof the collector current will be .(a) 1.39 mA (b) 3.7 mA(c) 5.33 mA (d) 7.73 mAQ70. An npn transistor under forward-active mode of operation is biased at I C = 1mA, and has a total emitter-base capacitance C π of 12 pF, and the basewww.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-2010EE (Paper-II)transit time τ Fof 260 psec. Under this condition, the depletion capacitance ofthe emitter-base junction is. [useV T . 26mV](a) 2pF (b) 3pF (c) 4pF (d) 6pFQ71. The units of q/kT are:(a) V (b)1V − (c) J (d) J/KQ72. An n channel JFET has I DSS = 1 mA and V p = -5 V. The maximum transconductanceis .(a)0.2m (b)0.4m (c)0.6m (a)0.8mQ73. Figure shows four D type FFs connected as a shift register using an XORgate. The initial state and 3 subsequent states for 3 clock pulses are alsogiven.State Q A Q B Q C Q DInitial 1 1 1 1After the 1 st clock 0 1 1 1After the 2 nd clock 0 0 1 1After the 3 rd clock 0 0 0 1The state Q A Q B Q C Q D after the fourth clock pulse is:(a) 0 0 0 0 (b) 1 1 1 1 (c) 1 0 0 1 (d) 1 0 0 0Q74. The truth table for XOR and EQUALITY in low level logic is:(a) L, H, H, L ; H, L, L, H(b) H, L, L, L ; L, L, L, H(c) H, L, L, H ; H, L, L, L(d) H, L, L, H ; L, H, H, LQ75. A µP with a 16 bit address bus is used in a linear memory selectionconfiguration (i.e. Address bus lines are directly used as chip selects ofmemory chips) with 4 memory chips. The maximum addressable memoryspace is:(a) 64 k (b) 16 k (c) 8 k (d) 4 kwww.iesacademy.com Email: iesacademy@yahoo.com Page-13__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010EE (Paper-II)Q76. Among the logic families, the family which can be used at very highfrequency greater than 100 MHz in a 4 bit synchronous counter is:(a) TTLAS (b) CMOS (c) ECL (d) TTLLSQ77. The Karnaugh map of 4 variable Boolean function A, B, C, D is shown inFigure. x indicates ‘don’t care’ combinations. The minimal SOP expressionfor the function is:(a) A+D (b) A+D (c) A+D.B (d) A+D.CQ78. A Boolean function f is to be realised only by NOR gates. Its K map is givenbelow.The realisation is:www.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-2010EE (Paper-II)Q79. The Boolean expression AB+AB+AB⋅ ⋅ ⋅ is equivalent to(a) A +B(b) AB ⋅ (c) A+B (d) A⋅BQ80. The circuit shown in Figure is:www.iesacademy.com Email: iesacademy@yahoo.com Page-15__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010EE (Paper-II)(a) Full adder (b) Full subtractor (c) Shift register (d) Decade counterQ81. A 4-bit modulo-16 ripple counter uses JK flip-flops. If the propagation delayof each FF is 50 ns, the maximum clock frequency that can be used is equalto(a) 20 MHz (b) 10 MHz (c) 5 MHz (d) 4 MHzQ82. For a µP system using mapped IO which of the following statement(s)is NOT true.(a) Memory space available is greater(b) Not all data transfer instructions are available(c) IO and Memory address spaces are distinct(d) IO address space is greaterQ83. PCHL is an instruction in 8085 which transfers the contents of the registerpair HL to PC. This is not a very commonly used instruction as it changesthe flow of control in a rather ‘unstructured’ fashion. The instruction can beuseful in implementing(a) If …..… then …..… else …..… construct(b) While …….… construct(c) Case …….… construct(d) Call ………. constructQ84. Start and stop bits do not contain any ‘information’ but are used in serialcommunication for(a) Error detection(b) Error correction(c) Synchronisation(d) Slowing down the communicationQ85. The logic circuitry in ALU is:(a) Entirely combinational(c) Combinational cum sequential(b) Entirely sequential(d) None of the abovewww.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-2010EE (Paper-II)Q86. The output data lines of microprocessors and memories are usually tristatedbecause(a) More than one device can transmit information over the data bus byenabling only one device at a time(b) More than one device can transmit information over the data bus at the sametime(c) The data lines can be multiplexed for both input and output(d) It increases the speed of data transfers over the data busQ87. Two dimensional addressing of 256 X 8 bit ROM using 8 to 1 selectorsrequires ………….(how many) NAND gates.(a) 48 (b) 72 (c) 84 (d) 98Q88. In a microprocessor system the stack is used for(a) Storing the program return address whenever a sub-routine jump instructionis executed(b) Transmitting and receiving input-output data(c) Storing all important CPU register contents whenever an interrupt is to beserviced(d) Storing program instructions for interrupt service routineQ89. The following instructions have been executed by an 8085 μPADDRESS(HEX)INSTRUCTION6010 LXI H, 8A 79 H6013 MOV A, L6015 ADD H6016 DAA6017 MOV H, A6018 PCHLFrom which address will the next instruction be fetched?(a) 6019 (b) 0379(c) 6979(d) None of the abovewww.iesacademy.com Email: iesacademy@yahoo.com Page-17__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010EE (Paper-II)Q90. RST 7.5 interrupt in 8085µP executes the interrupt service routine frominterrupt vector location(a) 0000 H (b) 0075 H (c) 003C H (d) 0034 HQ91. Purpose of start bit in RS 232 serial communication protocol is:(a) To synchronize receiver for receiving every byte(b) To synchronize receiver for receiving a sequence of bytes(c) A parity bit(d) To synchronize receiver for receiving the last byteQ92. In a 16-bit microprocessor, words are stored in two consecutive memorylocations. The entire word can be read in one operation provided the first(a) Word is even(b) Word is odd(c) Memory location is odd(d) Memory address is evenQ93. In a BJT,α(a)β= (b)α+ 1αβ= (c)α − 1βα= (d)β− 1β+1α= βQ94. For the switching waveform shown in Fig. for a power transistor, the averagevalue of switch-on power loss at a switching frequency ƒ is (ƒ = 1/T).(a)4⋅ ⋅ (b)6 ⋅ ⋅ (c) 3 ⋅ ⋅ (d) 8 ⋅ ⋅ ⋅www.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-2010EE (Paper-II)Q95. Match the devices on the left hand side with the circuit symbols on righthand side and give the correct answer from the codes given below:(A) BJT(B) MOSFET(C) IGBT(D) MCTCodes:A B C D A B C D(a) 2 3 4 1 (b) 2 3 1 4(c) 3 2 1 4 (d) 3 2 4 1Q96. In a single-phase diode bridge rectifier, the source voltage is 200 sin ωt withω = 2π x 50 rad / sec and the load is R = 50 Ω. The power dissipated in theload resistor R is:www.iesacademy.com Email: iesacademy@yahoo.com Page-19__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010EE (Paper-II)(a) 3200 Wπ(b) 400 Wπ(c) 400 W(d) 800 WQ97. Current-ripple factor for a rectifier circuit is defined aswww.iesacademy.com Email: iesacademy@yahoo.com Page-20__(a)2⎛I⎞or⎜ ⎟ −1⎝ Io⎠IIor(b) −1o25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290(c)2⎛ I ⎞o⎜ ⎟ −1⎝Ior⎠IIo(d) −1Where I or = rms value of output current and I o = dc value of output currentQ98. A thyristor, when triggered, will charge from forward-blocking state toconduction state if its anode to cathode voltage is equal to(a) Peak repetitive off-state forward voltage(b) Peak working off-state forward voltage(c) Peak working off-state reverse voltage(d) Peak non-repetitive off-state forward voltageQ99. Turn-on time of an SCR in series with RL circuit can be reduced by(a) Increasing circuit resistance R(b) Decreasing R(c) Increasing circuit inductance L(d) Decreasing L.Q100. A power semiconductor device of thermal resistance 0.6°C/W has its heatsink at 90°C. In case the junction drop is 1.5 V for a load current of 30 A DC,the junction temperature would be:(a) 63°C (b) 107°C (c) 117°C (d) 127°CQ101. An UJT is employed to fabricate a relaxation oscillator. When energised, itfails to oscillate. This may be due to1. High base-terminal voltage V BB2. Too large a capacitor3. Low value of charging resistor4. Large interbase resistanceFrom these, the correct statements are:(a) 1, 3 (b) 1, 2, 3 (c) all (d) 2, 4Q102. In a single-phase semi-converter, with discontinuous conduction andextinction angle β < π, freewheeling diode conducts for(a) α (b) π - β (c) β - π (d) Zero degreeQ103. In a 3-phase half-wave diode rectifier, if V mp is the maximum value of perphase voltage then each diode is subjected to a peak inverse voltage ofor

India’s No 1IES AcademyIES-2010EE (Paper-II)(a) V mp (b) 3V mp(c) 2 V mp (d) 3V mpQ104. A DC chopper is fed from 100 V DC. Its load voltage consists of rectangularpulses of duration 1 msec in an overall cycle time of 3 msec. The averageoutput voltage and ripple factor for this chopper are respectively(a) 25 V, 1 (b) 50 V, 1 (c) 33.33 V, 2 (d) 33.33 V, 1Q105. Match List I with List II and give the correct answer by using the codes givenbelow:List-I: Chopper configurationsList-II: Output Voltage WaveformsA. Voltage-commutated chopperB. Load-commutated chopperC. Current-commutated chopperwww.iesacademy.com Email: iesacademy@yahoo.com Page-21__D. Ideal dc chopperCodes :A B C D A B C D(a) 2 4 1 3 (b) 2 4 3 1(c) 4 2 1 3 (d) 2 1 4 3Q106. Consider the following statements:1. Inherent short-circuit operation 2. Regeneration capability3. Need for inverter grade thyristors 4. Voltage spikes across the loadWhich of these features are associated with CSI?(a) 1,2, and 3 (b) 2,3 and 4 (c) 1, 3 and 4 (d) 1, 2 and 4Q107. The output voltage waveform of a 3-phase square-wave inverter contains25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES Academy(a) Only even harmonics(b) Both odd and even harmonics(c) Only odd harmonics(d) Only triplen harmonicsIES-2010EE (Paper-II)Q108. In McMurray commutation circuit, the circuit turn-off time is:(a) Dependent on load current and independent of operating frequency(b) Dependent on load current and also on load power factor(c) Independent of load current and dependent on operating frequency(d) Independent of load current and dependent on recovery period.Q109.From the trapezoidal function in a, the functions at b and c are obtained by(a) Differentiation of a and b(b) Differentiation of a and integration of b(c) Integration of a and b(d) Integration of a and differentiation of bQ110. A modulated signal f(t)cosωct is multiplied by another signal2f(t)cos ωct . If f(t)F(ω)f(t) cos ω t ↔↔ then2(a) F(ω)+F(ω+ωc)+F(ω- ωc) (b) F(ω)+ [ F(ω+ω )+F(ω- ω )](c)1 1f(t)+ f(t)cos 2ωct2 2c1 12 2cc1 1F(ω)+ F(ω+2ωc)+F(ω-2ω c)2 4(d) [ ]cosωct to yieldQ111. The peak to peak value of AM signal is 50 V and peak to peak value ofmodulating signal is 16 V. The percentage of modulation is:(a) 32% (b) 47% (c) 64% (d) 16%Q112. An AM signal with a carrier of 1 kW has 200 W in each sideband. Thepercentage of modulation is:(a) 20% (b) 89.4% (c) 44.7% (d) 40%www.iesacademy.com Email: iesacademy@yahoo.com Page-22__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010EE (Paper-II)Q113. The maximum power efficiency of an AM modulator is:(a) 25% (b) 50% (c) 75% (d) 100%Q114. Coherent demodulation of FSK signal can be effected using(a) Correlation receiver(b) Bandpass filters and envelope detectors(c) Matched filter(d) Discriminator detectionQ115. Match List-I with List-II and select the correct answer using the codes givenbelow the lists:List-IList-IIA. Detection of a periodic signal in noise 1. Increase in bandwidthB. Recovery of a band-limited signal from 2. Slope overload errorits uniformly sampled valuesC. Finer quantization of signals 3. Nyquist’s rateD. Delta modulation 4. Cross correlationCodes:A B C D(a) 4 3 1 2(b) 3 4 2 1(c) 4 3 2 1(d) 4 2 1 3Q116. Which of the following demodulator(s) can be used for demodulating thesignal x ( t ) = 5(1 + 2 cos 200 πt) cos 20000πt ?(a) Envelope demodulator(b) Square-law demodulator(c) Synchronous demodulator(d) All the aboveQ117. The bit stream 01001 is differentially encoded using ‘Delay and EX OR’scheme for DPSK transmission. Assuming the reference bit as ‘1’ andassigning phases of ‘0’ and ‘π’ for 1’s and 0’s, respectively, in the encodedsequence, the transmitted phase sequence becomes(a) π 0 π π 0 (b) 0 π π 0 0 (c) 0 π π π 0 (d) π π 0 π πQ118. A PCM system has a range of ±4 volts and is to be encoded with 3 bits. Thestep size is:(a) 0 (b) +2 V (c) -2 V (d) 1 VQ119. An 8 level encoding scheme is used in a PCM system OF 10 kHz channel BW.The channel capacity is:(a) 80 KBS (b) 60 KBS (c) 30 KBS (d) 18 KBSwww.iesacademy.com Email: iesacademy@yahoo.com Page-23__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010EE (Paper-II)Q120. A super heterodyne radio receiver with an intermediate frequency of 455 kHzis tuned to a station operating at 1200 kHz. The associated image frequencyis ......... kHz.(a) 1200 kHz (b) 2110 kHz (c) 1100 kHz (d) 455 kHzwww.iesacademy.com Email: iesacademy@yahoo.com Page-24__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES AcademyIES-2010EE (Paper-II)1. Ans. (d)2. Ans. (b)3. Ans. (a)4. Ans. (d)5. Ans. A→ 2, B → 3, C → 4, D → 16. Ans. (c)7. Ans. (d)8. Ans. (c)9. Ans. (c)10. Ans. (a)11. Ans. (b)12. Ans. (a)13. Ans. (a)14. Ans. (a)15. Ans. (b)16. Ans. (a)17. Ans. (a)18. Ans. (b)19. Ans. (b)20. Ans. (a)21. Ans. (c)22. Ans. (d)23. Ans. (b)24. Ans. (d)25. Ans. (c)26. Ans. (d)27. Ans. (a)28. Ans. (c)29. Ans. (c)30. Ans. (d)31. Ans. (d)32. Ans. (a)33. Ans. (d)34. Ans. (a)35. Ans. (a)36. Ans. (a)37. Ans. (c)Answer41. Ans. (d)42. Ans. (d)43. Ans. (a)44. Ans. (b)45. Ans. (b)46. Ans. (a)47. Ans. (b)48. Ans. (b)49. Ans. (a)50. Ans. (a)51. Ans. (a)52. Ans. (b)53. Ans. (c)54. Ans. (b)55. Ans. (c)56. Ans. (a)57. Ans. (d)58. Ans. (c)59. Ans. (a)60. Ans. (c)61. Ans. (d)62. Ans. (d)63. Ans. (c)64. Ans. (c)65. Ans. (b)66. Ans. (b)67. Ans. (d)68. Ans. (b)69. Ans. (c)70. Ans. (a)71. Ans. (b)72. Ans. (b)73. Ans. (d)74. Ans. (d)75. Ans. (a)76. Ans. (c)77. Ans. (b)78. Ans. (d)81. Ans. (c)82. Ans. (d)83. Ans. (a)84. Ans. (c)85. Ans. (a)86. Ans. (a)87. Ans. (d)88. Ans. (a)89. Ans. (b)90. Ans. (c)91. Ans. (b)92. Ans. (d)93. Ans. (b)94. Ans. (b)95. Ans. (a)96. Ans. (c)97. Ans. (a)98. Ans. (b)99. Ans. (d)100. Ans. (c)101. Ans. (a)102. Ans. (d)103. Ans. (b)104. Ans. (c)105. Ans. (a)106. Ans. (d)107. Ans. (c)108. Ans. (a)109. Ans. (a)110. Ans. (d)111. Ans. (b)112. Ans. (b)113. Ans. (b)114. Ans. (a)115. Ans. (a)116. Ans. (d)117. Ans. (d)118. Ans. (d)www.iesacademy.com Email: iesacademy@yahoo.com Page-25__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290

India’s No 1IES Academy38. Ans. (d)39. Ans. (d)40. Ans. (b)IES-201079. Ans. (a)80. Ans. (b)EE (Paper-II)119. Ans. (b)120. Ans.(b)5. Ans. A→ 2, B → 3, C → 4, D → 159. Ans. (a)−14qFBε 3.9 × 8.854 ×10VT( new) = VT( old ) + ;Ci = =-8Cid 400 × 10-191.6 × 10 × FB− 1 = 1+3.9 8.854 10−14× ×−8400 × 10−142× 3.9× 8.854×1012 2FB =− =− 1.08×10 /cm−19 −81.6 × 10 × 400 × 10Threshold voltage is always negative for p-channel. Hence p-type.120. Ans. (b)fi = 455 kHz; fs = 1200 kHz; f = Fs + 2fi= 1200 + 910 = 2110 kHzimagewww.iesacademy.com Email: iesacademy@yahoo.com Page-26__25, 1 st Floor, Jia Sarai, Near IIT. New Delhi-16 Ph: 011-26537570, 9810958290