Gate Model Paper

7/27/2019 Gate Model Paper

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ELECTRICAL ENGINEERINGPRACTICE SET-1Q.1:- The resistance of a strip of copper ofrectangular cross-section is 2. A metal ofresistivity twicethat of copper is coated on its upper surface to athickness equal to that of copper strip. Theresistance of composite strip will be(a) 6 (b) 4/3 (c) 3/2 (d) 3/4

Q.2:- The electric field lines and equipotential lines(a) Are parallel to each other.(b) Are one and the same.(c) Cut each other orthogonally.(d) Can be inclined to each other at any angle.Q.3:- For an SCR, di/dt protection is achievedthrough the use of(a) R in series with SCR.(b) L in series with SCR.(a) RL in series with SCR.(c) RLC in series with SCR.Q.4:- In a linear system, an input of 5 sin wtproduces an output of 10 cos wt. The outputcorresponding to input 10 cos wt will be equal to(a) + 5 sin wt (b) - 5 sin wt (c) + 20 sin wt (d)20sin wt.Q.5:- For the system shown in figure, with adamping ratio of 0.7 and an undamped naturalfrequency wof 4 rad / sec, the values of K and are

(a) K = 4, a = 0.35(b) K = 8, a = 0.455(c) K = 16, a = 0.225(d) K = 64, 0.9Q.6:- A single instruction to clear the lower fourbits of the accumulator I 8085 assembly languageis:(a) XRI OHF (b) ANI FOH (c) XRI FOH (d) ANI OFH.Q.7:- The p-type substrates in a conventional pn-

junction isolated integrated circuit should beconnected to:(a) Nowhere, i.e., left floating.(b) A dc ground potential.(c) The most positive potential available in thecircuit.(d) The most negative potential available in thecircuit.Q.8:- The velocity of electromagnetic ratio wavesis(a) 3 x(b) 3 x(c) 3 x

(d) 3 xQ.9:- A certain 8- bit microprocessor executesSUB A, B by loading B to the ALU, then loadingA tothe ALU, Subtracting A from B, and storing theresult in B. Which of the following instructionswouldcause the ZERO flag to be set?(a) SUB(X), (X) +

(b) SUB )X), (X) +(c) SUB( X), (X)(d) all of the aboveQ.10:- which of the following induction motor willhave the least shaft diameter?(a) 20 HP, 2880 rpm(b) 20 HP, 1440 rpm(c) 20 HP, 960 rpm(d) 20 HP, 730 rpmQ.11:- In plasma state a gas(a) ( a) loses electrical conductivity(b) ( b) attracts moisture(c) ( c) becomes perfect dielectric medium(d) ( d) conducts electricityQ.12:- If the secondary winding of the idealtransformer shown in the figure below, has 40turns, thenumber of turns in the primary winding formaximum power transfer to the 2 ohm resistor willbeIDEA TRANSFORMER

( a) 20 (b) 40 (c) 80 (d) 160Q.13:- A 6 pole 3-phase wound-rotor inductionmachine is driven by another machine at 1800 rpm.The rotor of the induction machine is connected toa 50Hz system. If the mechanical rotation of therotor is in the same direction as the rotor windingflux rotation, then frequency of the stator voltagewill be(a) 50Hz (b) 140 Hz (c) 150 Hz (d) 200 HzQ.14:- A universal motor runs at(a) Higher speed will dc supply and with lesssparking.(b) Higher speed with ac supply with less sparking.(c) Same speed both ac and dc supplies.(d) Higher speed with ac supply but with increasedsparking at the brushes.Q.15:- Two 550 kVA alternator operate in parallel tosupply the following loadsI. 250 KW at 0.95 p.f. laggingII. 100 KW at 0.85 p.f. leadingOne machine is supplying 200 KW at 0.9 p.f.lagging. The p.f. of other machine must be(a) 0.89 leading (b) 0.95 leading (c) 0.95 lagging (d)0.89 lagging


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Q.16:- In a 110 volts compound generator, thearmature, shunt and series windings are 0.06 ohm,27.5 ohm and 0.04 ohm respectively. The loadconsists of 200 lamps; each rated at 55 W, 110 V.findthe total e.m.f. when the machine is connected forlong shunt operation.(a) 12 V (b) 72 V (c) 100 V (d) 120 VQ.17:- 1 Bagasse is

(a) Low quality coal.(b) A fuel consisting of wood.(c) Fibrous portion of sugarcane left afterextracting the juice.(d) A kind of rice straw.Q.18:- The copper armature winding of a motor issubjected to an operating temperature of 80C.The room temperature is 20 C. The percentagechange in resistance of the armature winding fromcold staring condition to normal running will benearly:(a) 10% (b) 16% (c) 20% (d) 24%Q.19:- Magnetic flux density at a point distance Rdue to an infinitely long linear conductor carryingacurrent is given by(a) B = (b) B =(c) B = (d) B =Q.20:- A zener diode works on the principle of(a) Tunneling of charge carriers across thejunction.(b) Thermionic emission.(c) Diffusion of charge carriers across the junction.(d) Hoping of charge carriers across the junction.

Q.21:- Two resistance 100 } 5 } 15 areconnected in series. If the errors are specified asstandard

deviations, the resultant error will be(a) } 10 (b) } 10.6 (c) } 15.8 (d) } 20

Q.22:- The unit impulse response of a system isgiven as c (t) = +6e2t. The step response of thesamesystem for 0 is equal to(a) 3e2t +4et+1(b) 3e2t +4et1(c) 3e2t +4et 1(d) 3e2t +4et 1Q.23:- Which of the following statements is true?(a) ROM is a Read/Write memory.(b) PC points to the last instruction that was

executed.(c) Stack works on the principal of LIFO.(d) All instructions affect the flags.Q.24:- If a transistor is operation with both of itsjunctions forward biased, but with the collectorforward bias greater than the emitter-base forwardbias, then it is operating in ht(a) Forward active mode.(b) Reverse saturation mode.(c) Reverse active mode forward saturation mode.(d) Forward saturation mode.Q.25:- Which type of transmission line will havethe maximum value of characteristic impedance?

(a) Open wire line.(b) Twin lead line.(c) Coaxial cable.(d) All have same impedance.Q.26:- The ALU of a microprocessor performsoperations of8-bit twos complement operands.What

happens the operation 7A A2is performed?

(a) Result = D8Overflow and negative flags set.

(b) Result = D8 Negative flag is set.(c) Result = D8No flags set.

(d) Result = 28overflow flag set.

Q.27:- Efficiency of a plant is secondaryconsideration for(a) Base load power plants.(b) Peak load power plants.(c) Both peak loads as well as base load powerplants.(d) Neither peak load nor base load power plants.Q.28:- An undesirable side effect of motionalinductance of large conduction specimens is(a) Skin effect (b) hysteresis (c) eddy currents (c)

dielectric lossQ.29:- if the rated voltage from the power lines isapplied to the primary of a single-phasetransformer which is operated on no-load, then(a) Both input voltage and current are sinusoidal.(b) Both input voltage and current are non-sinusoidal.(c) Input voltage is non-sinusoidal and inputcurrent sinusoidal.(a) D input voltage is sinusoidal and input currentis non sinusoidal.Q.30:- In all cases of electromagnetic induction,an induced voltage will cause a current to flow in aclosed circuit in such a direction that the magneticfield which is caused by that current will opposethe change that produces the current is theoriginal statement of(a) Lenzs law(b) Faradays law of magnetic induction.(c) Flemings law of induction(d) Amperes lawQ.31:- The sator and rotor pole number may bedifferent in a(a) Pole changing induction motor.(b) Reluctance motor.(c) Repulsion motor.(d) Synchronous motor.

Q.32:- Match List-1 with List-2 and select thecorrect answer using the codes given below thelists:List-1 List-2(Parts of a tubogenrator used in thermal powerplants (Materials from which these parts are made)(a) A. Steel core 1. Copper(b) B. Rotor core 2. Copper alloy(c) C. Stator windings 3. Silicon steel(d) D. Slip rings 4. Mild steela.i.1.a.i.1.a.i. 5. AluminumCodes:-


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(a) A B C D3 5 2 1(b) A B C D4 5 1 2(c) A B C D4 3 1 2(d) A B C D3 4 1 2Q.33:- The type of dc generator used for arc

welding purposes is a(a) Series generator.(b) Shunt generator.(c) Cumulatively compounded generator.(d) Differentially compound generator.Q.34:- In power station practice spinning reserveis(a) Reserve generating capacity that is in operationbut not in service.(b) Reserve generation capacity that is connectedto bus and ready to take the load.(c) Reserve generating capacity that is availablefor service but not in operation.(d) Capacity of the part of the plant that remainsunder maintenance.Q.35:- A load that has a resistance of 10 ohms is tobe connected to a supply that has a constantvoltage of 120 volts. If it is desired that the currentto the load be varied from 3 to 5 amperes, whatare the resistance and the current rating of theseries rheostat that permit this variation?(a) (a) 5 ohms, 5 A (b) 10 ohms, 10 A(b) (c) 20 ohms, 10 A (d) 20 ohms, 10 AQ.36:- Maxwells divergence equation for themagnetic field is given by(a) (a) B = 0 (b) 0(b) (c) B = (d)

Q.37:- When a line commutated converter operatesin the inverter mode(a) It draws both real and reactive power from theA.C. supply.(b) It delivers both real and reactive power to theA.C. supply.(c) It delivers real power to the A.C. supply.(d) It draws reactive power from the A.C. supply.Q.38:- Match List-1 with List-2 and select thecorrect answer using the codes given below thelists:List-1 List-2(Parameter measured (Bridge)

A. Audio frequency 1. Maxwell bridgeB. High Q inductor 2. Hay bridgeC. Dielectric loss 3. Wien bridgeD. Low Q inductor 4. Schering bridgeCodes:(a) A B C D3 4 2 1(b) A B C D3 2 4 1(c) A B C D4 2 1 3(d) A B C D1 4 2 3

Q.39:- Match List-1 with List-2 and select thecorrect answer using the codes given below thelists:List-1 List-2(Time functions) (Laplace transforms)

A. E2 (t-2) 1.B. 2.C. t / 2 3.4.

Codes:(a) A B C2 1 3(b) A B C2 3 4(c) A B C1 2 3(d) A B C3 1 4Q.40:- What is the distance of the following code?(a) 2 (b) 3 (c) 4 (d) 1Q.41:- The common-emitter short-circuit currentgain of a transistor

(a) Is a monotonically increasing of the collectorcurrent.(b) is a monotonically decreasing function(c) Increases with for low , reaches a maximum,and then decreases in .(d) is not a function ofQ.42:- Which of the following is circularly polarizedantenna?(a) Helical (b) yogi.uda (c) Small circular loop (d)Parabolic reflectorQ.43:- A single instruction to clear the lower fourbits of the accumulator in 8085 assembly languageis:(a) XRI OFH (b) ANI FOH (c) XRI FOH (d) ANI OFH

Q.44:- Which of the following equipment wouldneed high starting torque as compared to runningtorque?(a) Lathe machine(b) Electric Locomotive(c) Centrifugal pump(d) Reciprocating compressor.Q.45:- All of the following comparisons betweenmetals and metal alloys and ceramics are trueexcept(a) ceramic compounds crystallize more slowlythen metallic compounds(b) ceramic compounds have higher melting

temperatures than metallic compounds(c) Metallic compounds are better conductors orcurrent than ceramic compounds at highertemperatures.(d) Ceramic compounds are able to resist greatertensile stresses than metallic compounds atroom temperatures.Q.46:- Two 3-phase transformers are to beconnected for parallel operation. Which one of thefollowing arrangements is impossible?(a) Transformer A: primary Y; secondary YTransformer B: primary ; secondary(b) Transformer A: primary ; secondary Y


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Transformer B: primary ; secondary(c) Transformer A: primary Y ; secondaryTransformer B: primary ; secondary(d) Transformer A: primary ; secondaryTransformer B: Primary ; secondaryQ.47:- A centre zero ammeters connected in therotor circuit of a 6-pole 50 Hz induction motormakes 30 oscillations in one minute. The rotorspeed is

(a) 970 (b) 990 (c) 1010 (d) 1030Q.48:- which of the following capacitor start split-phase induction motor will have the largest valueof capacitance?(a) . H.P., 3450 rpm(b) . H.P., 1725 rpm(c) . H.P. , 1140 rpm(d) . H.P., 1140 rpm.Q.49:- The most appropriate operating speed inrpm of generators used in Thermal, Nuclear andHydro-power plants would respectively be:(a) 3000, 300 and 1500(b) 3000, 3000 and 300(c) 1500, 1500 and 3000(d) 1000,900 and 750Q.50:- A 220 V dc machine has an armatureresistance o f 1-ohm. If the full load current is 20A,thedifference in the induced voltage when themachine is running as a motor, and as a generatoris(a) 20 V (b) zero (c) 40 V (d0 50 VSolution:-1:-(b) Copper and coated metal strips haveresistance of 2 ohms and 4 ohms respectively.These twostrips are in parallel. Hence the resistance of the

composite strip will be (2x4) / (2+4) =4/3 ohms.

2:-(c) Since no electric can exist along any surface,all points of which are at the same potential,electric field lines and equipotential lines areorthogonal to each other.3 :-( b) For an SCR, di/dt protection is achievedthrough the used of L in series with SCR. Asnubbercircuit connected across an SCR is to suppress dv/ dt.4 :-( d) Sin wtCos wtDifferentiatingCos wt2 Sin wtAn input of 10 Cos wt will cause aResponse of20 Sin wt.5:- (c) M (s) ==

The changed equation iss (s+2) + K (1 + as) = 0 or s2 + s (2+ak) + k =0Compare with s2+2 s+ = 0K = = 42 = 16;2 = (2+ak)a= = = 0.2256:- (b) A single instruction to clear the lower fourbits of the accumulator in 8085 assembly languageis ANI FOH.

7:- (d) it should be connected to the most negativepotential available in the circuit.8:- (b) The velocity of electromagnetic wave is 3 x10 m / s.9:- (a) Note that(X) + signifies locate the operand at location X,and then increment X by 1.(X) signifies decrement X by 1, and then locatethe operand at location oldX minus one.Following is a diagram of a section of linearmemory containing the location X.

Consider the instruction:SUB(X), (X) +Observe that at both times the same operand,namely a, is being accessed. Since aa = 0 thezeroflag will be set.10:- (a) The horsepower is proportional to theproduct of rpm (N) and torque (T)Since the horsepower of all the motors is thesame, the motor having highest rpm (2880 inthis case) will have least torque. Diameter of theshaft depends on torque, therefore, 20 HP, 2880rpmmotor will have the least diameter of shaft.11:- (d) in plasma state a gas is fully ionized and itconducts elasticity.12: (c) For maximum power transfer to 2 ohmresistor, the reflected resistance in the primarycircuitshould be 8 ohm.Therefore,= 2 so that = ( ) 2 x

Or = 22 x 2 8 ohmThus, N= 2 x 40 = 80 turns.

13:- (b) P = 6, Nr =1800 rpm, f= 50 Hz

Let the stator voltage frequency be f.

Then, f= sf.Also, =Or =Or = , s being slipOr s = or (1s) =Or . s = or =Or + 1000 =1800+1000=2800f = = 140 Hz.


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14:- (a) A universal motor runs at higher speedwith DC supply and with less sparking.15:- (a) Total P = 250 + 100 = 350 kW

Total Q = 250 tan cos1 0.95100 tan cos1 0.85= 250 x 0.3287100 x 0.6197= 82.17161.97 = 20.196 kVAR

= 200 tan cos1 0.9 96.86 kVAR= the reactive power of the other machine is 20.19696086 = 76.67 kVAR

The second machine will operate at leadingp.f. Pof this machine is

350200 = 150 kW

Cos = tan cos1= 0.890 leading.16:- (d) = 0.06 ohm= 27.5 ohm= 0.04Total load current.= 200 x = 100 A= = 4 A.= + = 100 + 4 = 104Aemf = 110 + 104 (0.06 + 0.04) = 120.4 V.

17:- (c) Bagasse is fibrous portion of sugarcaneleft after extracting the juice.18:- (c) For the present problem, the readersshould consider armature as a copper conductionthrough which the current flows.We know that for copper= 0.00393 (at 20C)Hence, = [1 + (8020)]= . X 60=0.00393 x 60 = 2.358Hence percentage change in the value of theresistance = 23.58%.19:- (c) This is a simple and standard derivation to

show that magnetic flux density B around aninfinitely long straight filamentary wire carrying acurrent I is I / 2R where R is the perpendiculardistance of the point of intersection form the wire.20:- (a) In Zener diode the carriers are acceleratedby electric field. When they collide with atomsthey ionize the atoms due to their kinetic energy.Hence an avalanche break down occurs due to thelarge increase in the number of carriers.21:- (c) = 100 ohm 5 ohm,= 150 ohm 15 ohmR = +The errors are specified at standard deviations orare probable errors. In this case,R ==== ohms.22:- (b) The unit step response is the integral ofunit impulse response.Unit step response

= [4 + 6 e2 _] dt

= 4 e _ 3 e 2 _ I _= 4 e _ 3 e 2 _ 123:- (c) Stack works on the principle of LIFO is thetrue statement.

24:- (b) It is operating in the reverse saturationmode.25:- (b) The characteristic impedance Zo, forvarious types of transmission line sins givenbelow:Transmission Line ZoOpenwire line 300600 Twinlead line 250300 Coaxial cable 5075

26:- (a) 7 A 0111 1010 0111 1010A2 1010 0010 + 0101 11101101 1000

Result = D8.

Sign bit = 1, so negative flag set. The sign of theresult is the same as the sign of the numbersubtracted; thus. Overflow flag set.27:- (b) Main purpose of peak load plant is to meetthe peaked demand. Such plants normally run forshort durations and, therefore, their efficiency is asecondary consideration.28:- (c) When a conductor is moved towards thenorth pole of a bar magnet, if will experience achange of magnetic flux as a result of which therewill be an induced emf. This emf will give rise to aninduced current in the conductor, in a direction(determined by Lenzs law) that will oppose themovement of the conductor. Such currents arecalled eddy currents.In general, eddy currents occur in conductors thatexperience a change of flux. This fluxchange can be due either to the mechanicalmotion in a magnetic field as in the armature of amotor,or to a changing current in the wires woundaround the soft iron core of a transformer. In bothcases,

eddy currents cause i2 R losses due to heating.These can be minimized by laminating the ironcore,i.e., building it up with thin sheets covered by athin coating of insulating varnish. This reduces theeddy currents.29:- (d) Magnetizing current is usually non-sinusoidal at the flux density values normallyused; andunder no load condition, the total currentcomprises magnetizing current and core losscomponentcorrect.

30:- (a) Lenzs law30:- (b) Reluctance motor.32:- (d) A - 3, B4, C1, D2.33:- (d) As the terminal voltage should fall withincrease in the arc current for welding work, thedifferentially compounded generator is quitesuited for this purpose.34:- (b) In power station practice spinningreserve is to reserve generating capacity that isconnected to bus and ready to take the load.35:- (c) The 10 ohm load when connected to 120 Vsupply with take a current of 120/10 =12A without


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rheostat in the circuit. Since it is desired to restrictthe current flow through the load at 3 to 5amperes, the voltage drop in the load will be3 x 10 = 30 volts at 3 amperes, and5 x 10 =50 volts at 5 amperesWhen the voltage drop across the load is 30 V, thevoltage drop in the rheostat must be120 30 = 90volts. Since the same current flows through therheostat, the resistance of the rheostat must be 90

/ 3= 30 ohms.When the voltage drop across the load is 50 V, thevoltage drop in the rheostat must be 120 50 = 70volts. Since the same current flows through therheostat, the resistance of the rheostat must be 70/5=14 ohms. Thus rating of rheostat must be 30ohms and 5 amperes.36:- (b) No explanation needed somethingstandard and evident as the net magnetic fluxthrough anyclosed surface is always zero.37:- (c) A line commutated converter operates, inthe rectifying mode converting ac to dc for the first0 to 90 and in the inverting mode for phaseangels 90 to 180. When the dc voltage is negativepower flow is from dc to ac and the converterfunctions as inverter. As dc power is fed back it isrealpower.38:- (b) A3, B2, C4, D - 139:- (a) A2, B1, C340:- (a) Two41:- (c) The common emitter short-circuit currentgain of transistor increases with for low reachesa maximum, and then decreases with further

increase in42:- (a) only a helical antenna is the circularlypolarized antenna.43:- (b) ANI FOHAn accumulator is a resister in which the result ofan arithmetic or logic operation is formed.44:- (b) only locomotive needs starting torquemore than the running torque45:- (d) Ceramic materials are more brittle thanmetals. Ceramic materials are able to resistenormousshear stresses. The tension and compressionstrength of the ceramic materials are not

comparabledue to the enormous shear resistance. Under atensile load the stress will be concentrated atcracksand flaws in the ceramic material. A more ductilematerial will be able to lower the stressconcentration through plastic deformation.However, if plastic deformation cannot occur dueto highshear resistance, the stress concentration willcontinue to increase as the load increases. Thecrackwill extend and a brittle fracture will take place.

46:- (b) Even (c) is possible because we can havethe phase group as yd 1 and Dy 1 or yd 11 and Dy11.(b) is impossible because there shall be a phasedifference of 30 in the voltages of thecorrespondingphases of the two-transformers on the secondaryside.

47:- (b) Rotor frequency f= 0.5 H;

f= sfs = = 0.01= = =1000= (1s)= 1000 (10.01) = 990 rpm48:- (d) Out of the given range of motors, motor at(d) will require highest torque. Therefore,capacitor in the auxiliary winding for this motorwould have the largest value.49:- (b) Thermal power plant generators areinvariably high speed machines. Nuclear powerplantsalso use similar machines with the only difference

in the source of energy. Hydroelectric powerplantsare invariably low speed machines therefore,choice (b) is appropriate.50:- (c) Motor: = = = V()= 220(20 )Gen.: = += = V + ()= 220 + (20 +)= = 40 V.ELECTRICAL ENGINEERINGPRACTICE SET- 2Q.1:- Two materials have resistance temperature

coefficients of 0.004 and 0.0002 respectively at agiventemperature. In what ratio should the wires madeof these materials be connected in series so as tohave anoverall temperature coefficient of 0.002?(a) 1:2 (b) 2:3 (c) 9:10 (d) 15:16Q.2:- Consider the two fields,E = 120 cos (10 t- x) V / mAnd

H = A cos (10 t- x) / m.The values of A and which will satisfy theMaxwells equation ina linear isotropic,

homogeneous,loss-less-medium with = 8 and= 2 will beA (in A / m) (in rad / m) (a) 1 0.0105(b) 1 0.042(c) 2 0.0105(d) 2 0.042Q.3:- A chopper operating at a fixed frequency isfeeding an R-L load. As they duty ratio of thechoppe isincreased from 25% to 75%, the ripple in the loadcurrent.


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(a) Remains constant.(b) Decreases, reaches a minimum at 50% dutyratio and then increases.(c) Increases, reaches a maximum at 50% dutyratio and then decreases.(d) Keeps on increasing as the duty ratio isincreased.Q.4:- A sinusoidal waveform, when observed on anoscilloscope, has a peak to peak amplitude of 6cm.

Ifthe vertical sensitivity setting is 5 V / cm, the rmsvalue of the voltage will be(a) 10.6 V (b) 11.1 V (c) 12.6 V (d) 15 VQ.5:- Which of the following is an example of anopen-loop system?(a) Household refrigerator.(b) Respiratory system of an animal.(c) Stabilization of air pressure entering into amask.(d) Execution of a program by a computer.Q.6:- A binary tree T has n leaf nodes. The numberof nodes of degree 2 in T is(a) (a) n (b) n1(b) (c) n (d)Q.7:- An n-channel silicon (= 1.1 eV) MOSFET was

fabricated using npoly silicon gate and the

thresholdvoltage was found to be 1 V. Now, if the gate is

changed to ppoly-silicon, other things remaining

the same,the new threshold voltage should be(a)0.1 V (b) 0 V (c) 1.0 V (d) 2.1 VQ.8:- Scintillation is(a) Variation of physical dimensions under theinfluence of magnetic field.(b) Deionization of gases under low pressures.

(c) Production of flashes of light by somesubstances when struck by alpha, beta of gammarays.(d) Change in dielectric constant of substanceswith change in humidity.Q.9:- Which of the following statements is true?(a) ROM is Read /Write memory.(b) PC points to the last instruction that wasexecuted.(c) Stack works on the principle of LIFO.(d) All instructions affect the flags.Q.10:- In which range the cost of a synchronousmotor is likely to be comparable to the cost of

inductionmotor?(a) Low H.P., high speed.(b) High H.P., low speed.(c) High H.P., high speed.(d) Low H.P., low speed.Q.11:- which one of the theories given below isrelated to the theory of the thermocouple?(a) Piezoelectric effect (b) Skin effect (c) See backeffect (d) Faradays LawQ.12:- For the purpose of analysis exact equivalentcircuit of a transformer is usually replaced by an

approximate equivalent circuit. In doing so errorsintroduced due to winding copper loss and coreloss areof differential nature. Due to this the analysis byapproximate equivalent circuit gives fairlysatisfactoryresults. Under the circumstance, which one of thefollowing is correct in respect of losses referred toapprox. Equivalent circuit?

(a) This accounts for somewhat greater primarywinding copper loss and more cores less coreloss.(b) This accounts for somewhat lesser primarywinding copper loss and more core loss.(c) This accounts for somewhat greater secondarywinding copper loss and less core loss(d) This accounts for somewhat lesser secondarywinding copper loss and more core loss.Q.13:- Consider the following statements: In a 3-phase induction motor connected to a 3-phasesupply; ifone of the lines suddenly gets disconnected, thenthe1. Motor will come to a standstill.2. Motor will continue to run at the same speedwith line current unchanged.3. Motor will continue to run at a slightly reducedspeed with increased line current.4. Rotor currents will have both sf and a (2-s) fcomponent frequency where s is the slip and f isthesupply frequency.Of these statements:(a) 1 and 4 are correct(b) 1 and 2 are correct(c) 3 and 4 are correct

(d) 2 and 3 are correctQ.14:- While a 2-phase ac servomotor is inoperation, if the voltage across the control fieldwindingbecomes zero, then the motor has a tendency torun as a single-phase induction motor. To preventthis(a) rotor having high mass moment of inertia isused for such a motor(b) drag cup type of light rotor with high rotorresistance is preferred(c) a low rotor resistance is used(d) The number of turns in the control field winding

used is less than the main reference wingding.Q.15:- The inertia constant of a 100 MVA, 11 KVwater wheel generators is 4. The energy stored inthe rotorat the synchronous speed is(a) (a) 400 MJ (b) 400 KJ(b) (c) 25 MJ (d) 25 KJ.Q.16:- A separately excited dc generator is feedinga shunt motor. If the load torque on the motor ishalvedapproximately.(a) Armature currents of both motor and generatorare halved.


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(b) Armature current of motor is halved and that ofgenerator is unaltered.(c) Armature current of generator is halved andthat of motor is unaltered.(d) Armature currents of both motor and generatorare unaltered.Q.17:-Which variety of coal has lowest calorificvalue?(a) Steam coal

(b) Bituminous coal(c) Lignite(d) AnthraciteQ.18:- The Current through an electrical conductoris 1 ampere when the temperature of theconductor is0C and 0.7 ampere when the temperature of theconductor is 1200C must be(a) 0.08 A (b) 0.16 A (C) 0.32 A (d) 0.64 AQ.19:- The velocity of a travelling electrmagneticwave I freee space is given by

(a) (b) (c) (d)

Q.20:- When a thyristor is negatively blased(a) all the three junctions are negatively blased .(b) outer junctions are positively blased and theinner junction is negatively biased.(c) outer junction are negatively baised and theinner junction is positively biased a.(d) the junction near the anode is negativelybiased and the one near the cathode is positevelybiased.Q.21:- In the two-wattneter nethod of neasurungpower in a balanced threee-phase circuit, onewattmetershows zero and thr other positve maximum. Thelad powe factor is(a) zero (b) 0.5 (c) 0.866 (d) 1.0

Q.22:- If the unit step response of a system is aunit impusle function, then the transfer function ofsuch asystem will be(a) 1 (b) 1/s (c) s (d) 1 / s2Q.23:- The probability that a number selected atrandom between 100 and 999 (both inclusive willnotcontain the digit 7 is(a) 16/25 (b) (9/10)3 (c) 27/75 (d) 18/25Q.24:- In the ciruit shown in the figure, N is a fintiegain amplifier with a gain of k, a very inputimpendance,

and a very low output impedance. The inputimpendance of the feedback amplifier with thefeedback Z

connected, as shown will be(a) Z (1-1 / k)(b) Z (1-d)(c) Z (k-1)(d) Z (1-k)Q.25:- A satellite carrying antenna system,transmitter, receiver and power supply is knownas(a) geostationary satellite

(b) orbital satellite(c) active satellite(d) passive satelliteQ.26:- In a virtual memory system, the addressspace specified by the address lines of the CCPUmust thanthe secondary storage size.(a) smaller, smaller(b) smaller, larger(c) larger, smaller(d) larger, largerQ.27:- Wires are made by(a) spinning(b) rolling(c) drawing(d) turningQ.28:- Based on the cohesive energy of an ionicsolid, which of the following is not a property ofthe ionicsolid?(a) It forms relatively stable and hard crystals(b) It is a poor electric conductor(c) It has a higher vaporization temperature(d) None of the above.Q.29:- If the wave-form of the voltage impressedon the primary of a Y- bank contains a 5thharmonic, the

wave-forms of the resultant voltages of primaryand the secondary would bePrimary Secondary(a) Peaked peaked(b) Peaked flat-topped(c) Flat-topped peaked(d) Flat-topped flat-toppedQ.30:- In a self-excited induction generator, tokeep the frequency of generated voltage constantwith theincrease in load the speed of the inductionmachine should be(a) Increased.

(b) Decreased.(c) Maintained less than the rated synchronousspeed.(d) Maintained more than the rated synchronousspeed.Q.31:- The speed of a universal motor can becontrolled by(a) introducing a variable resistance in series withthe motor(b) tapping the field at various points(c) centrifugal mechanism(d) all of the above steps


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Q.32:- A large a.c. generator, supplying to n infinitebus, has a sudden short-circuit occurring at itsthevoltage behind the transient reactance to remainconstant immediately after the fault, theacceleration ofthe generator rotor is(a) inversely proportional to the moment of inertiaof the machine

(b) inversely proportional to the square of thevoltage(c) directly proportional to the square of the short-circuit current(d) Directly proportional to the short-circuit power.Q.33:- An electric train employing a dc seriesmotor is running at a fixed speed, when a suddenslight dropin the mains voltage occurs. This would result in(a) drop in speed and rise in current(b) rise in speed and drop in current(c) rise in speed and rise in current(d) Drop in speed with current unaltered.Q.34:- Ball mill is used in power plants using(a) multi-stage expansion(b) water softening(c) fly ash removal from flue gases(d) Pulverized fuel firingQ.35:- In the circuit shown in figure,= 10 micro-amperes. The value of resistance is

(a) 1 kilo-ohm(b) 10 kilo-ohm(c) 100 kilo-ohm(d) 1 Mega-ohmQ.36:-The equation of a plane wave may be writtenas (with) usual symbols(a) =(b) =(c) =(d) =Q.37:- A single-phase voltage source square-waveinverter feeds pure inductive load. The waveformof theload current will be(a) Sinusoidal (b) rectangular (c) trapezoidal (d)triangular

Q.38:- A 35V dc supply is connected across aresistance of 600 ohm in series with an unknownresistance. Avoltmeter having a resistance of 1.2 k-ohms reads5V. The value of resistance will be(a) 120 ohm (b) 400 ohm (c) 1.8 k-ohm (d) 2.4 k-ohmQ.39:- When a unit-step input is applied, a secondorder under damped system has a peak overshoot

of OPoccurring at If another step input equal inmagnitude to the peak overshoot OP is applied at.t =then thesystem will settle down at(a) 1 + OP (b) 1OP (c) OP (d) 1.0Q.40:- Let R be a symmetric and transitive relationon a set A. Then(a) R is reflexive and hence an equivalence relation(b) R is reflexive and hence a partial order(c) R is not reflexive and hence not a anequivalence relation(d) None of the above.Q.41:- In a bipolar transistor at room temperature,If the emitter current is doubled, the voltageacross itsbase-emitter junction(a) Doubles (b) halves (c) increases by about 20mV (d) decreases by about 20 mVQ.42:- layer has maximum ionic density of 3.5 xelectrons per cc. The critical frequency for thislayer will be(a) 1.68 MHz (b) 400 MHz (c) 400 KHz (d) 40 KHzQ.43:- An instruction used to set the carry Flag in acomputer can be classified as(a) Data transfer (b) arithmetic (c) logical (d)Program control

Q.44:- Figure of Merit is used to(a) compare the efficiency of the thermoelectricmaterials(b) measure the extent of doping of intrinsicsemiconductors(c) compare the extent of purity of semi-conductormaterials(d) None of the above.Q.45:- A certain photoconductive cell is known tohave a critical wave-length of 0.5 micrometer. Thentheminimum energy required to move an electronfrom the valence band to the conduction band is:

(a) 0.96 electric volt (b) 0.31 electron volt (c) 0.62electric volt (d) 2.48 electron voltsQ.46:- A 50 Hz operation, a single-phasetransformer has hysteresis loss of 200 W and eddycurrent loss of100 W. Its core loss at 60 Hz operation will be(a) 432 W (b) 408 W (c) 384 W (d) 360 WQ.47:- Cogging and crawling are phenomenaassociated with(a) cage induction machines and they areessentially the same(b) squirrel cage induction machine, the former ata fraction of its rated speed and the latter during


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starting(c) squirrel cage induction machine, the formerduring starting and the latter at a fraction of itsratedspeed(d) Wound rotor induction machines and they arereduced by skewing, chording and distribution ofwindings.Q.48:- Match List-1 (type of single-phase motor)

with List-2 (type of appliance) and select thecorrectanswer using the codes given below the lists:List-1 List-2A. Permanent magnet type 1.RocketB. Shaded pole 2. Refrigerator compressorC. Universal 3. Sewing machineD. Capacitor shunt, capacitor run induction motor4. Photocopying machineCodes:(a) A B C D1 2 3 4(b) A B C D1 2 4 3(c) A B C D4 1 3 2(d) A B C D1 4 3 2Q.49:- The fifth harmonic component of theinduced voltage in 3-phase ac generator can beentirelyeliminated by using a winding pitch of(a) 2 / 3 (b) 4 / 5 (c) 5 / 6 (d) 6 / 7Q.50:- Consider the following drive systems:1. Chopper fed dc series motor2. Chopper fed dc shunt motor3. Chopper fed permanent magnet dc motor

4. Brushless dc motor drive5. Inverter fed 3-phase induction motor6. Inverter fed 3-phase synchronous motorFor the development of a battery operated electriccar the possible options are(a) 1 , 3 and 5(b) 2 , 4 and 6(c) 1 and 5(d) 1 , 4 and 5Solution1:- (c) Let the materials be in the ratio of k = x / y= 0.002= 0.002

= 0.0020.004k + 0.000 = 0.0020.002k = 0.0018=Hence, the materials should be in the ratio 9:10.

2:- (d) E / H = the characteristic impedance of the

medium.3:- (a) Load voltage == E = EfThere are two ways to vary either by varying f or.Here frequency is fixed and is varied. As thefrequency is kept constant ripple remainsconstant.4:- (a) Amplitude of the signal is = 15 V.rms value is = 10.6 V.5:- (d) Execution of a program by a computer is anexample of an open-loop system.6:- (b) It can be proved by induction that a strictly

binary tree with n leaf nodes willhave a totalnumber of2n-1 nodes. So number of non-leaf nodes is (2n-1)n = n-1.7:- (c) 1.O V8:- (c) Certain crystals such as zinc sulphide,sodium iodide, antracene and naphthalene, etc.produce a briefflash of light each time they are struck by an alphaor beta or gamma particles. The production of aflash oflight by striking the crystals mentioned above,with alpha, beta or gamma rays, is called

scintillation.9:- (c) Stack works on the principle of LIFO.10:- (b) the cost of an induction motor increasedisproportionately in high H.P. range and also asoperatingspeed reduces. It is, therefore, in this range wherethe cost of the two machines is comparable.11:- (c) An electromotive force results from adifference of temperature between two junctions ofdissimilar metals in the same circuit.This effect was first noted by Thomas JohannaSee back. The difference of electric potential whichresults


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from the difference in junction on temperatures isdependent upon the metals used, the temperaturesofthe junction, and the intimacy of contact betweenthe two metals. Such a combination of dissimilarmetals,when used to produce an emf, is called athermocouple, and has many uses in themeasurement of

temperature.

12:- (b)Shall be slightly greater than and therefore,slightly greater core loss Current flowing throughis nowsomewhat less than and therefore reduced copperloss in itNote: - If the shunt branch is shifted to 2-2, thenthe answer would be (c). It depends on which

approximatecircuit is used. The one given above is morecommon.13:- (c) The motor will not stop. It will continue torun as a single phase motor with two phases of thewindings connected in series (for a star-connected) and third phase open; while for a deltaconnectedmotor, one phase of the winding and two otherphases in series of the winding are in parallel. Thefield inthe air gap is pulsating which can be resolved intoa forward rotating components. The rotor,therefore, has

both s f and (2s) f component frequencies.14:- (b) Drag cup type of light rotor with high rotorresistance is preferred.15:- (a) Inertia constant HMega joules of energy stored in the rotating massof the alternator at=Thus, 4 =E = 400 MJ.16:- (a) Since field winding currents of the twomachines are not disturbed and the torque isproportional to

the product of armature current and field flux,when the torque reduced to half, the armaturecurrent inboth also reduces to half.17:- (c) Lignite coal has lowest calorific value.18: (b) Let be the temperature coefficient.Then = Ro (1 + t)Where is resistance at t C and is resistance at 0CAssuming that for a given potential to 1 / R

We have= = 1 +. 1000.7 amps,The current I, at 1200C is given by= = 1 +. 1200= 1 + 0.0043 x 1200 = 6.16I = 1 / 6.16 = 0.16 amp.19:- (c) A standard relation VO =20:- (c) When a thyristor is negatively biased, outerjunctions are negatively biased and the innerjunction ispositively biased.21:- (b) the wattmeter readOneThen otherThus whenever load p.f. angle becomes 60 oneof the watt meters would read zero.For the given condition the load p.f. isCos 60 = 0.522:- (c) Input r (t) = u (t) R (s) = 1 / sOut put c (t) = (t) C (s) = 1Transfer function = = s.23:- (d) Probability that the unit digit is not 7 is 9 /10. Probability that the tens digit is not 7 is 9 / 10.Probability that the hundreds digit is not 7 is 8 / 9.So, probability that the unit digit is not 7 and thetens

digit in not 7 and the hundreds digit is not 7 is:(9 / 10) (9 /10)(8 /9) = 18 /25.24:- (d) From Millers theorem = Z / 1 K.25:- (c) The active satellite carries antenna systemtransmitter receiver and power supply. It works asanactive micro-wave repeaters, relay and signal tothe receiving station either instantly or afterstorage in itsmemory and waiting until the satellite faces theearth based receiving station.26:- (c) Larger, smaller.27:- (c) Wire-drawing process is used for making

wires of various diameters.28:- (d) the cohesive energy, which is the energyneeded to take the solid apart into positive andnegativeions, is relatively high for ionic solids. Therefore,they should be poor electrical conductors sincethere areno free elections available. They should be hardand stable with high vaporization temperaturesand highmelting points.29:- (b) Peaked- flat topped.


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30:- (a) When a slip becomes negative, theinduction machine acts as a generator, therefore,the rotorspeed should be more than the rated synchronousspeed. Further, as the load increases, slipmagnitudeshould increase as the power output isapproximately proportional to slip magnitude forsmall slips.

Therefore, speed will have to be increased.31:- (b) It can be controlled by tapping the field atvarious points.32:- (a) M =M : Moment of inertia of the machine: Second time derivative of the load or the torqueangle which turns out to be sameas rotor acceleration.: Shaft power: Electrical power outputSince 0 on occurrence of a short circuit,We have =33:- (d) In a series motor, the torque isapproximately proportional to current squared.The train resistancespeed curve is such that there is very littleincrease in torque with speed; we can assume thattorqueremains constant. Therefore, the armature currentremains constant with increase in applied voltage,theback emf reduces, which is achieved by a drop inspeed.34:- (d) Ball mill is used in power plants usingpulverized fuel firing.35:- (c) Let the current flow through resistancewhen12V Battery is removed. So,

Similarly current flow in resistance When + 12 Vbattery is removed. So,Since the two voltages are in opposite directions,their currents will subtract. Hence,= 10 x12(1000x1000+)12(470x1000+)10x (1000x1000+) x(470x1000+)+ 1470x100016.6x =0Solving for we have=10, 1000 ohms (rejecting the negative value)36:- (a) One may arrive at the correct choice by

comparing the two sides dimensionally. Since 1 /has thedimension of velocity squared,The pertinent choice is =37:- (d) The waveform of the load current will betriangular.

38:- (d) The voltage across is = 35 5 = 30V. The

current in the circuit is

39:- (a) It will settle down at 1+ OP.40:- (c) Let aRb. Since the relation is symmetricbRb. Since transitivity holds good, aRb and bRaimplied aRa.Also bRa implies aRa and bRb. If R has to be anequivalence relation, it has to be reflexive, i.e. forany xbelonging to A, xRx should hold good. So, R neednot be reflexive and so R need not be andequivalencerelation.For example, let a = (1, 2, 3)Let R = {(1,2),(2,1),(1,1),(2,2)}R is both symmetric and transitive but R is notreflexive as (3,3) is not present in R.41:- (c) Its base-emitter junction increases byabout 20 mV.42:- (b) Critical Frequency, fc = 9= = 16.839 MHz.43:- (b) Arithmetic

44:- (a) Figure of merit is used to compare theefficiency of thermo-electric materials.45:- (d) The minimum energy of a photon requiredto excite an electron from the valence band to theconduction band is the forbidden energy gap ofthat semiconductor material. The relationshipbetween thewavelength of the photon and the energy gap isgiven by== energy gap = minimum energy required to movean electron from the valence band to theconduction band, in electron volts.= Critical

wavelength of the photon (micrometers).1.24 = constant that arises from the Plancksconstant.Substituting the given data,= = 2.48 electron volt.46:- (c) If the operation of the transformer is at thesame rms value of the voltage, then


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Eddy current loss,= f2Thus eddy current loss in not affected. And thetotal loss is 179.3+100=279.3W. This doesnot tally with any of the given answers. Assume,the before that the flux density value is not charge.Then= 200 x =240 W= 100 x )2 = 144 W.Total loss = 384 W.47:- (c) Cogging and crawling are phenomenaassociated with squirrel cage induction machine,the formerduring starting and later at a fraction of its ratedspeed.48:- (d) A1, B4, C3, D - 2.49:- (b) Coil span factor for harmonic is= Cos nWhere is the angle by which the coil is short of fullpitch?= Cos = 0Thus fifth harmonic component gets eliminated byusing a coil pitch of 4/5.50:- (a) 1, 3 and 5 are Correct.ELECTRICAL ENGINEERINGPRACTICE SET- 3

Q1. In the figure below, the current of 1 ampereflows through the resistance of:

(a) 4 ohms (b) 20 ohms (c) 30 ohms (d) 12 ohmsQ2. Give thatE = time and space dependent electric intensityvector = permeability of the medium = conductivity of the medium= permittivity of the mediumThe electromagnetic wave equation is given by

(a) E =0(b) E =0

(c) E =0(d) E = =0Q3. In machine tool drive application, the speed ofseparately excited dc motor is required to becontrolled both below

and above the rated speed of the motor. Whichone of the following methods is best suited for thispurpose? (=armature voltage, = field current and = field currentat rated speed)(a) (a) = variable(b) fixed, variable(c) V and variable, with(d) and variable, with

Q4. Creep in energy meters can be prevented by(a) Using extra turns on the voltage coil.(b) Having two holes on opposite sides of the disc.(c) Using a stronger brake magnet.(d) Using steel laminations of high permeability.Q5.Which one of the following statements are trueof a type I system having unity gain in the forwardpath and a unityfeedback?1. Positional error constant is equal to infinity.2. Acceleration error constant is equal to zero.3. Steady-state error to a unit step displacementinput is equal to one.Select the correct answer using the codes givenbelow:Codes:-(a) 1, 2 and 3 (b) 1 and 2 (c) 2 and 3 (d) 1 and 3Q6.The number of elements in the power set P (S)of the setS=, 1 (2, 3)}} is(a) 2 (b) 4 (c) 8 (d) None of theseQ7. A non transistor has a beta cut off frequencyof a 1 MHz, and common-emitter short-circuitslow-frequencycurrent of 200. Its unity- gain frequency and thealpha cut off frequency respectively are(a) 200 MHz, 201 MHz

(b) 200 MHz, 199 MHz(c) 199 MHz, 200 MHz(d) 201 MHz, 200 MHzQ8. Top loading is sometimes used with anantenna in order it increase its(a) Effective height.(b) Bandwidth.(c) Beam width.(d) Input capacitance.Q9. An I /O processor controls the flow ofinformation between(a) Cache memory and I / O devices.(b) Main memory and I / O devices

(c) Two I / O devices.(d) Cache and main memories.Q10. The most toxic pollutant obtained bycombustion of coal is(a) Carbon dioxide (b) Nitrogen (c) Smoke (d)HydrogenQ11.Forging iron at a temperature below therecrystallization temperature will increase thehardness of iron because(a) Internal stresses do not appear in the iron.(b) Crystal defects such as dislocations areformed.


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(c) Surface shrinkage from the forging operationputs pressure on the interior of the iron.(d) The increases in the density will cause poresand cavities in the metal to disappear.Q12. A set of 3 equal resistors, each of valueconnected in star across RYB in place of load asshown in the given figureconsumes the same power as the unbalanceddelta connected load. The value of is

(a) 33.33 ohm ( b) 100 ohm (c) 173.2 ohm (d) 300ohm

Q13. Approximate phasor diagram of 3-phaseinduction machines for different operatingconditions are indicated inList-1 (with usual notations). Match List-1 with theoperating conditions given in the List-2 and selectthe correctanswer using the codes given below the Lists:

Codes:(a) A B C D2 4 1 3(b) A B C D2 3 4 1(c) A B C D2 4 3 1(d) A B C D4 2 3 1

Q14. The armature current of a dc motor fed form athyristor power converter contains ripple. Thisripple in thearmature current affects.(a) Commutating capability of the motor.(b) Overload capacity of the motor.(c) Torque capability of the motor.(d) Controllability of the speed of the motor.Q15. Which of the following limit in the reactive

power output of a synchronous generator?1. Armature current.2. Field current.3. Load angle.4. Prime mover input.Q16. A dc machine has, conductors per pair ofpoles A, length of each armature conductor L,linear velocity ofarmature conductor and air-gap flux-densitydistribution B = Sin . The instantaneous emfs insuccessive conductorsunder one pole should be a series whole first twoterms are = Sin and = Sin (.The last term in this series will be(a) Sin ((b) Sin ((c) Sin ((d) Sin (Q17. Bulb turbines are(a) High speed turbines.(b) High pressure turbines.(c) Low head turbines.(d) High head turbines.Q18. In the figure below, the voltage across the 18ohm resistor is 90 volts. What is the total voltageacross thecombined circuit?

(a) 12 V (b) 16 V (c) 24 V (d) 40 VQ19. Consider the following statements regardingMaxwells equations in differential from (symbolshave the usualmeanings)1. For free space2. For free space3. For steady current4. For static electric fieldOf these statements:(a) 1 and 2 are correct(b) 2 and 3 are correct(c) 3 and 4 are correct(d) 1 and 4 are correct


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Q20. If the commutation angle of a diode rectifier(due to source inductance effect) is , then theinductive voltageregulation will be(a) (b) 1 + (c) 1 (d) Q21. Which one of the following instrumentsshould be used at M in the given figure of themeasurement ofmagnitude as well as direction of the

displacement?a. Permanent magnet moving coil voltmeterb. vacuum Tube voltmeter (VTVM)

( c) Transistor voltmeter (TVM)( d) Phase Sensitive Detector (PSD)Q22. (jw), (jw) are three transfer functions whosephase variations are shown in the given figure.The magnitudevariation with respect to frequency is the same forboth (jw) and (jw), but their phase variation is asindicated by thecurves labeled A and C in the given figure. Thetransfer function (jw) is such that(jw) = (jw) + (jw)

are respectively

(a) Minimum phase, all pass and non-minimumphase functions.(b) Minimum phase, non-minimum phase and allpass functions.(c) All pass, minimum phase and non-minimumphase functions(d) All pass non-minimum phase and minimumphase functions.Q23. In the interval (0,), the equation x = cos x hasa. No solution.b. Exactly one solution.c. Exactly two solutions.d. An infinite number of solutions.

Q24. A zener diode in the circuit shown in fig.below has a knee current of 5 mA, and a maximumallowed powerdissipation of 300 mW. What are the minimum andmaximum load currents that can be drawn safelyfrom the circuit,keeping the output voltageat 6 V?

(a) 0 mA, 180 mA(b) 5 mA, 110 mA(c) 10 mA, 55 mA(d) 60 mA, 180 mAQ25. Which of the following is UHF?(a) 40 GHz (b) 400 MHz (c) 400 KHz (d) 40 KHz

Q26. The Zenith Computer can execute 1,000,000instructions per second. A program running onthis computerperforms on average a one sector read and onesector writes for every 200 instructions that itexecutes. The disk drivehandling the I / O transfer requires 0.00010seconds each to perform the read and writeoperations. Assuming nooverlap of these operation, the percent of CPUtime spent in the wait state, is(a) 12% (b) 39% (c) 57% (d) 91%Q27. The percentage of silica in earths crust isnearly(a) 10% (b) 26% (c) 35% (d) 52%Q28. The viscoelastic behavior of an amorphouspolymer will change with increasing temperaturefrom its rigidstructure at low temperatures. The polymersbehavior may proceed through the followingstages:1. Leathery2. Rubbery3. ViscousWhat is the consecutive order of the stages it willpass through?(a) 1, 3 only (b) 2 ,3 only (c) 2 ,1, 3 (d) 1,2,3

Q29. A Buchholz relay is used fora. Protection of a transformer against all internalfaults.b. Protection of a transformer against externalfaults.c. Protection of a transformer against both internaland external faults.d. Protection and induction motors.Q30. In a 3-phase induction machine, motoringgenerating and braking operations take place inthe range of slip sgiven by(a) Motoring: 1


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Generating: 1Braking:(b) Motoring: 1Generating: 0Braking:(c) Motoring: sGenerating: 0Braking:(d) Motoring: 0

Generating: sBraking:Q31. While operating on variable frequencysupplies, the ac motors require variable voltage aswell in order to(a) Protect the insulation.(b) Avoid the effects of saturation.(c) Improve the commutation capabilities of theinverter.(d) Protect the thyristors from dv / dt.Q32. During the slip-test for determining the directand the quadrature axis synchronous reactance ofan alternator,the voltage across the open field circuit terminalsis(a) Dc voltage.(b) Ac voltage of supply frequency.(c) As voltage of slip frequency.(d) A modulated voltage with an envelope of slipfrequency.Q33. Consider the following statements regardingspeed control of dc motors1. Ward-Leonard method is suitable for constanttorque drives.2. Field control method facilitates speed controlbelow base speed.3. Armature resistance control method is more

efficient when compared to Ward-Leonard method.4. Field control method is suitable for constanthorse power drives.Of these statements:a. 1 , 2 and 3 are correctb. 1 ,3 and 4 are correctc. 2 , 3 and 4 are correctd. 1 and 4 are correctQ34. Betz law finds application in(a) MHD systems(b) Solar cells(c) Geothermal power plants(d) Wind mills

Q35. A current of 20 A flows through ammeters Aand B joined in series. Across A the potentialdifference is 0.2 V andacross B it is 0.3V. Find how the same current willbe divided between A and B when they are joinedin parallel.(a) = =10 A(b) = =8A(c) = =12 A(d) = =16 AQ36. For an infinite linear current, four loops areshown in the given figure. The magnetic flux wouldbe the maximum

through the loop number.

(a) 1 (b) 2 (c) 3 (d) 4Q37. Consider the following statements:-The diodes in a voltage source inverter (Mc Murryinverter) should be able to1. Withstand a large voltage in the reversedirection.2. Carry the commutating current excess of loadcurrent.

3. Provide the required reverse bias to theoutgoing thyristor.4. Feedback the reactive current to the sourceOf these statements(a) 1, 2 and 3 are correct(b) 1, 3 and 4 are correct(c) 2, 3 and 4 are correct(d) 1, 2 and 4 are correctQ38. An integrating digital voltmeter measures(a) True average value.(b) rms Value.(c) Peak value.(d) Peak to peak value.Q39. The band with of a control system is the

range of frequency over which C / R (jw) isgreater than or equal to(a) 1 and it depends only the undamped naturalfrequency of the system.(b) 1 and it depends only on the damping factor ofthe system.(c) 1 and it depends only on the undamped naturalfrequency of the system.(d) 1 / and it depends on both undamped naturalfrequency and the damping factor of the system.Q40. If at every point of a certain curve, the slopeof the tangent equals 2x /y the curve is (a) A Straight line

(b) A parabola(c) A Circle(d) An ellipse.


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Q41. The wave shape of V in figure below,

Q42. A 1000 KHz carrier is simultaneouslymodulated with 300 Hz, 800 Hz and 2 KHz audiosine waves.The frequencies present in the output will be(a) 1000 KHz, 300 Hz, 800 Hz and 2 KHz(b) 1300, Hz, 1800 Hz, 2100 Hz and 4100 Hz(c) 300 Hz, 500 Hz, 1200 Hz and 998 KHz(d) 998 KHz, 999.2 KHz, 999.7 KHz, 1000.3 KHz,10008 KHz and 1002.2 KHz.Q43. Consider a memory system with the following

parameters:= Cache Access Time = 100 ns= Main Memory Access Time = 1200 nsIf we would like to have effective (average)memory access time to be or more than 20%higher than cacheaccess time, the hit ratio for the cache must atleast be:(a) 80% (b) 90% (c) 98% (d) 99%Q44. Which of the following gem is green incolour?(a) Emerald (b) Sapphire (c) Ruby (d) DiamondQ45.The Microstructure composition of pearlite for

an C diagram consists of(a) Carbon dissolved in alpha iron having a bodycentered cubic structure.(b) Carbon dissolved in gamma iron having abody-centered cubic structure.(c) A mixture of body-cented alpha having a face-centered gamma iron.(d) Carbon dissolved in body-cented alpha ironand a C compound of higher carbon.Q46. Match List -1 with List-2 and select thecorrect answer using the codes given below thelists:List -1 List-2

(Equipment) (Function)A. Circuit Breaker 1. Voltage controlB. Lightning Arrester 2. Power controlC. Governors 3. Overvoltage protectionD. Exciter 4. Over current protectionCodes:(a) A B C D1 2 3 4(b) A B C D

4 1 2 3(c) A B C D2 3 4 1(d) A B C D4 3 2 1Q47. A voltmeter gives 120 oscillations per minutewhen connoted to the rotor of an induction motor.The statorfrequency is 50 Hz. The slip of the motor is(a) 2% (b) 2.5% (c) 4% (d) 5%.Q48. Consider the following steps:1. Reversing connections to the terminals of thecapacitor.2. Changing the position of the capacitor fromauxiliary winding circuit to main winding circuit.3. Revering supply connection to the mainwinding.4. Reversing supply connection to the auxiliarycircuit.While installing a new ceiling fan, if the fan motoris found to be rotating in the wrong direction, thenthe direction ofrotation of the motor can be corrected by(a) 1, 2 and 3 (b) 1, 2 and 4 (c) 1, 3 and 4 (d) 2, 3and 4Q49. A 3-phase fault occurs at his terminals of anunloaded alternator at an instant when the ac

component in onephase is at its maximum value. The variation in dccomponent during the post-fault period in thatphase will dependupon(a) Sub transient time constant.(b) Transient time constant.(c) Open-circuit time constant.(d) Armature time constant.Q50. A dc shunt motor runs at 500 rpm of 220 V. Aresistance of 4.5 ohm is added in series with thearmature for speedcontrol. The armature resistance is 0.5 ohm. The

current to stall the motor will be(a) 44 Amp (b) 50 Amp (c) 44.4 Amp (d) 60 AmpSolution1:- (d) There are three parallel banks which are inturn connected in series:Equivalent resistance of 20 ohm and 30 ohmParallel resistors = = 12 ohmsEquivalent resistance of 6 ohm, 4 ohm and 12 ohmbank = 2 ohms.Similarly equivalent resistance of 10 ohm and15 ohms resistors = = 6 ohms.Total resistance of the circuit = 12 + 2 + 6 =20ohms


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Current drawn from supply = = = 6ACurrent through 20 ohms resistor= 6 x = 3.6ACurrent through 30 ohms resistor= 63.6 = 2.4 AEquivalent resistance of 6 ohm, 4 ohm and 12 ohmbank is 2 ohm, voltage drop= 6x2 = 12 V.Current through 4 ohm resistor

= 12 / 6 = 2 ACurrent through 4 ohm resistor= 12 / 4 = 3 ACurrent through 12 ohm resistor= 12 / 12 = 1ACurrent through 10 ohm resistor= 6 x = 3.6ACurrent through 15 ohm resistor= 63.6 = 2.4A2:- (a) The electromagnetic wave equation is givenbyE= 03:- (c) With speed is reduced and with the speed isincreased above normal. Also with less than speedfalts, andwith greater than speed rises above normal. Toavoid overloading of either the field finding or thearmature winding,through little expensive: Choice (c) seems to besuitable.4:- (b) Creep in the energy meters can beprevented by having two holes on opposite sidesof the disc.5:- (b) 1 and 26:- (c) The set has 3 members. So its power set has23 = 8 members.7:- (a) = 1 MHz

= = 200== 200 x1 MHz= 200 MHzAnd, f == (1+B)= 201 MHz.8:- (a) Top loading of antenna is done mainly toincrease the effective height.9:- (b) Main memory and I / O devices.10:- (a) Carbon dioxide and carbon monoxide.11:- (b) The forging operation distorts the equiaxedmicrostructure of the metals and causes the

formation of crystaldefects such as dislocations. Elongated coarsegrains are also produced in the direction offormation. These effects ofthe forging operation crate iron that is brittle.12:- (b) Let the line voltage be V, the powerconsumed by the load impedances of the figureshown is V2 / 100W. Whenresistors, each of value are connected in star, thetotal power drawn is( = W.Since = ; = 100 ohm.13:- (c) A2, B4, C1.

14:- (a) The ripple in the armature current affectscommutation capability of the motor.15:- (a) Reactive power is not dependent upon loadangle and prime mover input.16:- (d) The phase difference between two adjacentconductors:() = Thus, = L u Sin (17:- (c) Bulb turbines are low head turbines.

18:- (a) since voltage across 18 ohm resistance is90 volts,Current through 18 ohm resistance= 90 / 18 = 5AEquivalent resistance of 3 ohm and 6 ohm bank is= 2 ohmsThis 2 ohms resistance is in series with 18 ohmresistance giving total resistance of 18+2 = 20ohmsThis 20 ohm resistance is in parallel with 5 ohmresistance giving equivalent resistance of= 4 ohmsHence total resistance circuit= 1+4 = 5 ohms.Since total resistance across de = 18+20 = 20ohms.Current through this branch is 5 AVoltage across de = 5x20 =100 V.= voltage across bc.Hence, current through 5ohm resistance be =100 / 5 = 20 ATotal current through ab = 20+5 =25 A.Since total resistance of the circuit is 5 ohm,Voltage E = 25x5 = 125 V.19:- (c) For free space are each zero. Thusstatements 3 and 4 are correct.20:- (d) = [

Where is the rectifier output voltage when thedelay angle; and Y, the commutation angle; areboth zero.Assuming to be zero= (1 + cos Y).Change in voltage due to source inductance effectisFractional regulation is=21:- (d) M should be able to detect phase reversalif not strictly phase sensitive. Phase sensitivedetector can well servethe purpose.

22:- (a) It can be minimum phase, all pass and non-minimum phase function.23:- (b) the point of intersection of the line y=x andthe curve y=cos (x), will be the root (s). If you drawthe graph it willbe clear that they meet only once in the giveninterval (0,). So, exactly one rootALLITER:Consider the function f (x) = x cos (x) f (0) is 0-1 =-1, a negative number F (0) is(-1) = +1, a positivenumber.


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So, the function should have odd number of rootsin the interval (0,). Also it can not have infinitelymany roots as cos(x) oscillates in (-1, 1), while x, increasesmonotonically and so infinite solution isimpossible. Hence B is the correctanswer.24:- (c) I == 3 / 50 A

= 0.3 / 5 A= 0.06 A= 60 mASo maximum load current (60-5) mA=mANow, = P / V = 300 / 6 = 50 mAmin = 60 mA50 mA =10 mA.25:- (b) The range for Ultra High Frequency is 300MHz to 3 GHz.26:- (d) The wait time can be calculated in thefollowing manner:Time to read 1 sector 0.0010Time to write 1 sector 0.0010Time to execute 200 instructions 0.0002Total program cycle time 0.0022Wait time = 0.0020 /0.0022* 100% 91%.27:- (b) Common elements in the Earths crustElement Percentage by weightOxygen 46.6Silicon 27.72Aluminum 8.13Iron 5.00Calcium 3.63Sodium 2.83Potassium 2.59Magnesium 2.09All other 1.4128:- (d) The polymer goes from a leathery stage, to

a rubbery and then a viscous stage. In the leatherystage thepolymer can be deformed readily but it cannotregain its shape quickly if the stress is removed. Inthe rubbery stagethe polymer can regain its original shape quickly.In the viscous stage the polymer deformsextensively by viscous flow.29:- (a) A Buchholtz relay is used for protection ofa transformer against all internal faults.30:- (a) motoring: 1 s 0Generating: 0 s -1Braking: s

31:- (a) Avoid the effects of saturation.32:- (c) Clearly, the voltage induced in the fieldwinding would have a frequency directly related tothe relative speed ofthe rotor and the synchronously rotating armaturemmf.33:- (d) Statements 1 and 4 only are correct.34:- (d) Betz law finds application in wind mills.35:- (b) Resistance of ammeter A is= = 0.01ohmResistance of ammeter B is= = 0.15 ohmWhen the ammeters A and B are joined in parallel,

= I = 20 x= 12 A= I = 20 x= 8 A.36:- (b) All the loops have equal areas. B at anydistance r from the wire is k / r. For anyrectangular loop of height h (inthe direction of the wire) and width w ( the wire),the

Flux is Kh inWhere a is the distance of the nearside from thewire.Thus, for 1, = k I inFor 2, = k 2I inFor 3, = k2I inFor 4, = kI in

= K I in (1+, = 2kI in (1+

= K I in (1+, = kI in (1+

The long terms do not change by significantamount. Thus, should be of highest value.37:- (c) 2, 3 and 4 are correct.38:- (a) An integrating digital voltmeter measures

true average value.39:- (d) The bandwidth of a control system in therange of frequency over which(Jw) |Is greater than or equal to 1 /. This is as perdefinition. Further, bandwidth depends on both-the undampednatural frequency and the damping ratio. Forinstance, the characteristic equation of a secondorder systemmay be expressed ass2 + 2 s + 2 =0Where is the undamped natural frequency ofoscillation and is the damping ratio. Also it can beshown that 2is the bandwidth. Thus the bandwidth isdependent on both and40:- (d) Slop (dy / dx) = (-2x / y)Ydy = -2x dxIntegrating both sides, y2 / 2 = (-2x2 / 2) + C i.e., x2/C + y2 / b2 =1,Ellipse, x2 / a2 + y2 / b2 = 1It is clear that the curve is an ellipse.41:- (a) One cycle time = 20 mSTime for source voltage to become 4.1 V duringpositive half cycle is given by4.1 = 10 Sin 0.314t, t in mS

Thus, t = 1 / 0.314 4.1 / 10= 1.345 mS.The diode B conducts now (A is already forwardbiased ) and the voltage across the load is (10Sin .314t4.1)V. Similar situation occurs in the negative halfcycle when Zener B is forward biased and Zener Aavalancheswhen source voltage becomes 4.1 V. Thus thevoltage across 10 k-ohm is given in figure (a)42:- (d) 300 Hz = 0.3 GHz; 800 Hz = 0.8 KhzFrequencies present in the output will be 1000


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I.E.999.7 KHz, 100.3 KHz 999.2 KHz, 1000.8 KHz,998 KHz and 1002 Khz.43:- (c) The hit ratio of at least 98% can be shownby the following formula:Effective System Access Time= H + (1+H)Where H is the hit ratio expressed as 8595 etc,and the other parameters as defined in thequestion

accordingly:100 H + 1200(1-H)Should be less than or equal to:+ 0.020 x = 100+20 = 120 nsMore than cache access time)Therefore:100 H +12001200 H = 120 and: H= 1090 / 1100=0.98Since H the answer of 98% or higher in (c) is thecorrect one.44:- (a) Emerald is a gem quality beryl, brightgreen in colour owing to the presence ofchromium.Sapphire is blue in colour and Ruby is red.45:- (d) Pearlite structure is an intimate mixture offerrite and cementite. Ferrite is gamma iron withface centeredcubic structure capable of dissolving up to 0.025%

cementite is a compound of composition FeC

with a carboncontent of 6.69%.46:- (d) A4, B3, C2, D1.47:- (c) circuit = slip x= s x 50s = x 100% = 4%48:- (d) 2, 3 and 4.49:- (d) will depend on armaturetime constant.

50:- (a) the motor is to be stalled, i.e., the motorspeed is reduced to zero by adding more and moreload on the shaft.Under that condition= = 44 A.

ELECTRICAL ENGINEERINGPRACTICE SET- 4Q.1 The transformed current in a certain branch ofcircuit is (2s + 10) / (s) (s+2). The current has afinalvalue of(a) 0 (b) 2 (c) 3 (d) 5

Q2. A transverse electromagnetic wave withcircular polarization is received by a dipoleantenna. Due topolarization mismatch, the power transferefficiency from the wave to the antenna is reducedto about(a) 50% (b) 33.3% (c) 25% (d) 0%Q3. In dielectric heating, if the capacitor is lossfree, the heat produced will bea. Zerob. Infinityc. Proportional to the value of capacitance.d. Proportional to the frequency.

Q4. A shunt type ohmmeter is shown in the figurebelow. With disconnected, the meter reads fullscale.S represents the meter current as a fraction of fullscale current with connected such the

Q5. The open loop transfer function of a controlsystem is given byThe smallest possible value of a for which thissystem is stable in the closed-loop for all positivevalues of K is(a) 0(b) 8(c) 10(d) 12Q6. A DOC formatted Hard Disk has followingparameters

No. of Cylinders = 1000No. of Heads = 517 sectors per cylinderWhat is the total Disk Capacity?(a) 10 MB(b) 32 MB(c) 85 Mb(d) 42.5 MBQ7.

= 3 K. Given = 0.9, the value of is given by(a) 0.3 mA /V(b) 0.33 mA / V(c) 3.0 mA / V(d) 3.0 A /V.Q8. PGM systems require regenerative repeatersoverlong distances. The correct sequence of the


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operations which such a repeater performs is(a) Timing, equalization and decision making.(b) Equalization, timing and decision making.(c) Timing, thresholding (decision) andequalization.(d) Thresholding, timing and equalization.Q9. Consider the following set of instructions:STCCMC

MOV A, BRALMOV B, AThis set of instructions(a) Doubles the number in Register by B.(b) Divides the number in Register by 2.(c) Multiples B by A(d) Adds A and B.Q10.The properties of air areI. Dry bulb temperatureII. Wet bulb temperatureIII. Dew point temperatureIV. Saturation temperatureIn case the relative humidity of air is 100% thenwhich of the above temperature will be equal?(a) 1 and 2 only(b) 3 and 4 only(c) I and 3 only(d) 1, 2, 3 and 4.Q11. Semiconductor A has a higher band gap thensemiconductor B. If both A and B have the samedimension, the same number of electrons at agiven temperature and the same electron and holemobilities, then(a) A has the same number of holes as B(b) A has a larger number of holes then B(c) A has less number o holes than B

(d) Any of the above statements (a), (b) or (c) couldbe true.Q12. In transformers, disc coil are generallypreferred for(a) Leading power factor.(b) High voltage winding.(c) Constant load.(d) Low voltages winding.Q13.Unbalanced supply voltage given to a 3-phase, delta-connected induction motor will cause(a) Zero sequence currents(b) Less heating of the rotor.(c) Negative sequence component current.

(d) All of the above.Q14. In ac series motor the purpose of providingcompensating winding is to(a) Reduce sparking at brushes.(b) Increase the torque.(c) Reduce heating of armature.(d) Minimum vibration.Q15. The parameters connected with the operationof a synchronous motor areI. SpeedII. Power factorIII. Armature current.

When the excitation of the motor is varied, whichparameters vary along with it.(a) 1 only(b) 2 only(c) 2 and 3 only(d) 1,2 and 3Q16. In series parallel control of dc series motors(a) Speed in series arrangement is four times thespeed in parallel arrangement.

(b) Speed in series arrangement is one fourth thespeed in parallel arrangement.(c) Speed in series arrangement is double of thespeed in parallel arrangement.(d) Speed in series arrangement is half of thespeed in parallel arrangement.Q17. Grounding is generally done in transmissionline at(a) The supply end(b) The receiving end(c) Middle of the line(d) Any where.Q18. The transformed current in a certain branchof a circuit is (2s+50 / (s+1) (s+1) (s+3). The valueof thecurrent for t=0_is(a) 0(b) 2(c) 3(d) 5Q19. Which of the following relations is correct?(a) (AB) =(b) (AB) =(c) (AB) =(d) All the three.Q20. A thyristorised, there phase, fully controlledconverter feeds a dc load that draws a current.

Then theinput ac line current to the converter has(a) An rms value equal to the dc load current(b) An average value equal to the dc load current(c) A peak value equal to the dc load current(d) A fundamental frequency component, whoserms value is equal to the dc load current,.Q21. The power in a resistor R is estimated bymeasuring the voltage and current using thevoltmeterammetermethod. Two different arrangements can be usedas shown in circuits 1 and 2. Less erroneousresults are obtained by adopting.

(a) Circuit 1 for low values of R


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(b) Circuit 2 for low values of R(c) Circuit 1 for high values of R(d) Circuit 2 for low and high values of R.Q22. The open loop transfer function of a unitynegative feed back control system is given byG (s) = K (s+2)/ (s+1) (s-70For K 6, the stability characteristics of the open-loop and closed loop configurations of the systemare respectively

(a) Stable and stable(b) Unstable and stable(c) Stable and unstable(d) Unstable and unstable.Q23. A relation over the set s = (x, y, z) is definedby (x, x), (x, y), (y, x), (x, z), (y, z), (y, y), (z, z) whatproperties hold for this relation?I. SymmetryII. ReflexivityIII. AntisymmetryIV. Irreflexivity.(a) 1 only(b) 2 only(c) 1 and 2(d) 1 and 1Q24. A saw-tooth generator is built using a UJTwith a constant current-charged capacitor C of 1 fdrivingthe emitter. If the voltage is 15 V and the capacitorcharging current is 1 mA, then the period of thesawtoothis approximately(a) 10 ms(b) 1 ms(c) 0.1 ms(d) 0.01 msQ25. Consider the following communication

systems1. Technology2. Radio communication3. Microwave communication4. Optical sequence of these systems from thepoint of view of increase of base bandchannels each on of them can accommodate is(a) 2,4,3,1(b) 3,4,1,2(c) 1,2,3,4(d) 4,2,1,3Q26. The number of bits needed to address 4Kmemory is

(a) 6(b) 8(c) 12(d) 16Q27. Three rods one made of glass, one of purealuminum and one made of wrought iron areheated to150C. All the rods are 15 mm in diameter and 300mm long. The lowest temperature at the free end ofthe rods will occur in case of(a) Aluminum rod(b) Wrought iron rod(c) Glass rod

(d) Temperature will be same for all the three rodsat free.Q28. With respect to a completely filled band,which one of the following statements is correct?(a) The total wave vector and the total velocity ofall electrons in the band is always zero.(b) The total wave vector and the total velocity ofall the electrons in the band is notnecessarily zero.

(c) Both (a) and (b) above.(d) None of the above.Q29. Buchholz relay works on the principle of(a) Production of eddy currents whenever loadchanges are rapid.(b) Ionization of transformers oil.(c) Magnetic hum due to sudden variation in load.(d) Generation of gas due to breakdown of theinsulation.Q30. When the supply voltage to an inductionmotor is reduced by 10% the maximum torque willdecreaseby approximately(a) 5%(b) 10%(c) 20%(d) 40%Q31. Consider the following statements regardingfractional horse power shaded-pole motor:1. Its direction of rotation is from unshaded toshaded portion of the poles.2. Its direction of rotation is from shaded tounshaded portion of the poles.3. It can remain stalled for short periods withoutany harm.4. It has a very poor power factor.Of these statements

(a) 1,3 and 4 are correct(b) 2,3 and 4 are correct(c) 2 and 4 are correct(d) 1 and 3 are correctQ32. The negative phase sequences in a threephase synchronous motor exist when(a) Motor is overloaded(b) Motor is under loaded(c) Unbalanced voltage is supplied(d) Motor armature is hot.Q33. Multiplex lap winding is used(a) To reduce commutation difficulties.(b) To increase voltage of machine.

(c) To increase number of parallel paths.(d) To reduce armature reaction effect.Q34. Temperature increase produces the followingeffect on a transmission line(a) Tension of the conductor and its sag increase.(b) Tension of the conductor and its sag decrease(c) Tension of the conductor decreases and its sagincreases.(d) Tension of the conductor increases and its sagdecreases.


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Q35. If in the figure shown V (t) = t, then I (t) will be

a unit

(a) Step function.(b) Impulse function.

(c) Doublet function.(d) Triplet function.Q36. Is equal to(a) 0(b) 1(c)(d) None of these.Q37. Triangular PWM control, when applied to athree phase, BJT based voltage source inverter,introduces(a) Low order harmonic voltages on the dc side(b) Very high order harmonic voltages on the dcside(c) Low order harmonic voltages on the ac side

(d) Very high order harmonic voltage on the dcside.Q38. A 150 V moving iron voltmeter of accuracyclass 1-0 reads 75V when used in a circuit understandardconditions. The maximum possible percentageerror in the reading is(a) 0.5(b) 1.0(c) 2.0(d) 4.0Q39.A Phase-lag compensation will(a) Improve relative stability.

(b) Increase the speed of response.(c) Increase bandwidth.(d) Increase overshoot.Q40. Function of a Modem is(a) To convert Digital Data to high frequencyanalog data.(b) Convert digital data to Analog signal and back.(c) Convert analog signals to digital signal.(d) Increase the voltage level of the data.Q41. Match List-1 with List-2 and select the correctanswer using the codes given below the lists:List -1 List -2A. Darlington amplifier in 1. A circuit using pnp

and npn transistors; used power amplifier.B. Common Base amplifier 2. A common sourceamplifier driving a common-gate amplifier.C. Complementary symmetry 3. A circuit withoverall voltage gain close to 1 and very large inputAmplifierD. Cascode amplifier 4. A circuit with low inputimpedance; mainly used in highFrequency applicationCodes:(a) A B C D1 2 1 2(b) A B C D

2 1 2 1(c) A B C D3 4 1 2(d) A B C D4 3 2 1Q42. When power ratios are expressed in dBm, thereference power is(a) 1 W(b) 1 mW

(c) 1 W(d) 1 W.Q43.The TRAP is one of the interrupts available inINTEL 8085. Which one of the followingStatements istrue of TRAP?(a) It is level triggered.(b) It is negative edge triggered.(c) It is positive edge triggered.(d) It is both positive edge triggered and leveltriggered.Q44. A sine wave voltage has a peak value of 170.Its value at 260 will be(a) 85 V(b) 170 V(c) -85 V(d) -170 VQ45. Which of the following crystallographicdefects contribute to electronic defects?1. Thermal vibration2. Point defects3. Line defects4. Surface defectsSelect the correct answer using the codes givenbelow:Codes:(a) 1,2 and 3

(b) 2,3 and 4(c) 1,3 and 4(d) 1,2 and 4Q46. The results of an open circuit test on a singlephase transformer areVoltage applied : : 100 VCurrent Drawn : : 0.5 APower consumed : : 30 WThe corresponding reactance of the transformer is(a) 200 ohms(b) 250 ohms(c) 400 ohms(d) 500 ohms

Q47. An induction motor having full load torque of60 Nm when delta-connected develops a startingtorque of 120 Nm. For the same supply voltage, Ifthe motor is changed to star-connection, thestartingtorque developed will be(a) 40 Nm(b) 60 Nm(c) 90 Nm(d) 120 NmQ48. Hysteresis motors are used for Hi-Q recordplayers because of their(a) Constant (synchronous) speed


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(b) Extremely steady torque(c) Insensitivity to supply voltage fluctuations(d) Non- dependence on centrifugal switchrequirementQ49. If a synchronous motor fails to pull intosynchronism after applying dc field current, theprobablecause may be(a) High core losses

(b) Low field current(c) High field current(d) Low short circuit ration.Q50. A series motor is working drawing a loadcurrent of 1 ampere form the lines. If now the loadisreduced such that the current drawn is halved, thespeed of the machine (neglecting saturation andarmature resistance) would be(a) Unchanged(b) Reduced by 50%(c) Reduced by100%(d) Increased by 100%Solution

1:- (d)2:- (a) 50%3:- (a) The power density generated in dielectricheating is not proportional to capacitance. Thefrequencyused in dielectric heating lies in the range of 1-50MHz. In dielectric heating, non-uniform heating

occursfor higher frequencies.4:- (d) =With connected,== = ===Where, =5:- (a)G (s) =Let the system be a unity feedback system.Then the ch.eqn Is:S(s+2) (s+a) + k(s+10) =0Or s (s2+s) (2+a) +ks+10k = 0Or s2+s2 (2+a) +s (2a+k) +10k = 0s3 1 (2k+k) second row constraints that as2 (2+a) 10k the next row inform us that (2a+k)(2+a)s1 0 a ands 10k 0 Smallest non-negative value of k= 0 aThus when a(2+a) condition also is satisfied.6:- (d) Disk capacity = 1000x5x17x512 Bytes= 435x1000 Bytes=42.5 MB.

7:- (c)= ; =1+= 1+1+ = 1+= 9= = 3 mA/ V8:- (b) the correct sequence of the operationswhich such a repeater performs is timing,equalization and

decision making.9:- (a) STC CY 1 1CMC CY CY 0MOV A, B A10:- (d) All four temperatures will be identical.11:- (b) The current density due to electrons in thevalence band of a completely filled valence ban is= ne ()Where n () is the sum of the velocity of all theelectrons in this band, n is the number of electionsper unit volume and is the average drift velocity ofelectrons.The total current density in a semiconductor or aninsulator is the sum of the current density dueto holes and the current density due to electrons.The electronic current is in a direction opposite tothehole current. The total current density J isobtained by the relationJ = Jh + Je = (p e h + n e e) Electrical ConductivityI = 2e ( ) 3/ ()For (Eg) (Eg)B12:- (b) Disc type coils are used for high voltagewinding.13:- (c) It will cause negative sequence componentcurrent.

14:- (a) It is to reduce sparking at brushed.15:- (c) The parameters are power factor andarmature current.16:- (b) In series parallel control, when the motorsare in parallel,Speed(Series motors)Since, is approximately equal to the appliedVoltage V,SpeedWhen the motor s are in series,SpeedThus speed in series arrangement is one fourth of

the motors when in parallel.17:- (a) Grounding is done in transmission line atthe supply end.18:- (b)

19:- (d)


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20:- (c)21:- (a) It is an elementary piece of knowledge. ForLow resistance measurements, if circuit 2 is used,theammeter resistance which may be comparablewith the low resistance being measured getsadded to theunknown and thereby causing larger error.22:- (b) G (s) =

Since there is a pole in RHP of complex s-plane,the open loop system is unstable.K(s+2) +(s+1) (s-7) =0Or s2 + s (k-6) (s-7) = 0s2 1 (2k-7) It is seen that for k the first column ofthes1 (k 0 Routh table has all entries of the samesign; hence thes (2k-) 0 system is stable.23:- (b) A relation is reflexive if every element ofthe set is related to itself. This is true; R includes(x,x),(y,y), and (z,z)A relation is irreflexive, if, no element is related toitself. This is clearly untrue for R.A relation is symmetric if, for any tow distinctelements of the set, say, x and y, then if x isrelated to y, y is related to x.Now, since R contains (x, y) and also (y, x), it mayappear to be symmetric at first sight.However, R also contains (y, z) but (z, y) is absent.We conclude that R not symmetric.A relation is Antisymmetry if for any tow distinctelements x and y, if x is related to y, y is notrelated to x. We observe (x, y) and (y, x) present isR, so R is not Antisymmetry.24: - (a) 10 ms.25:- (d) Optical communication, radio

communication, Telephony and Microwavecommunication.26:- (c) 212 = 4096 4 K27:- (c) Glass rod.28:- (b) Schrodinger equation is:+ V= EThe wave vector governs the motion ofelectrons in the same way that light wavesdeterminethat the motion of photons. In case of completelyfilled band, is zero, for the bound electrons areallconfined to a finite region. However the total

velocity of all the electrons in the band is notnecessarilyzero.29:- (d) Buchholz relay is a mechanical device thatmay be fitted to an oil immersed transformer. Abreakdown of the insulation in a transformer isalways accompanied by the generation of gas inthe oil. Aserous fault that will result in the rapid generationof this gas which tries to escape by way of the oilexpansion chamber

30: -(c) Since torque is approximately proportionalto voltage squared, when applied voltage reducesto 0.9times, normal, the torque also reduces to (0.9)2 =0.81 times the normal torque. Hence, anapproximatereduction of 20%31:- (a) 1, 3 and 4 are correct,32:- (c) When the unbalanced voltage is supplied.

33:- (c) For a multiplex winding the number ofparallel paths is equal to n x p, where n is flux ofwindingand p is the number of poles.34:- (c) The tension of the conductor decreasesand its sag increases.35:- (c) Then1 = I (s). = . C = 1I (s) = s.I (t) s a doublet36:- (a) zero37:- (d)38: - (c) The error specified is always with respectto full scale reading and this is the maximum errorthatmay be present at any deflectionThe % = x150 x x 100= 2.039:- (d) A phase lag compensation will increaseovershoot40:- (b) Function of a modem is to convert digitaldata to analog signal and back.41:- (c) A-3, B-4, C-1, D-2.42:- (b) When power ratios are expressed in dBm,the reference power is 1mW. `43:- (d) It is both positive edge triggered and leveltriggered.

44:- (d) At 270 it will have negative peak value i.e.,170 V.45:- (a) Choice (a) provides the better answer.46:- (b) No load current = 0.5A = I . No loadcurrent energy= I Cos = = 0.3 ANo load current magnetizing component= =Magnetizing reactance of transformer1 = = 250 ohms.47:- (a) Now since the voltage across the windingreduces to 1 / times the voltage when in deltaconnection the torque becomes (1 / )2 times, i.e., 1

/ 3rd.Starting torque reduces to 120/3 =40 Nm.48:- (a) The more prominent reason is quietoperation and ability to start against large inertia.And abilityto start against large inertia49:- (b) The probable cause can be low fieldcurrent.50:- (d) Reduction in load will cause increase in

speed.


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ELECTRICAL ENGINEERINGPRACTICE SET- 5Q1. If in the circuit shown, v (t) = t. the current I (t)

will be a

(a) Ramp function(b) Step function(c) Impulse function(d) DoubletQ2. A metal sphere with 1 m radius and a surfacecharge density of 10 Coulombs / m2 is enclosed inacube of 10m side. The total outward electricdisplacement normal to the surface of the cube is(a) 40 Coulombs(b) 10 Coulombs(c) 5 Coulombs(d) None of the above.

Q3. The main reason for connecting a pulsetransformer at the output stage of a thyristortriggeringcircuits to(a) Amplify the power of the triggering pulse.(b) Provide electrical isolation(c) Reduce the turn on time of the thyristor(d) Avoid spurious triggering of the thyristor dueto nose.Q4. A simple dc potentiometer is to bestandardized by keeping the side wire setting at1.0813 V. If bymistake, the setting is at 1.0138 V and the

standardization is made to obtain a source voltageof 1.0318V, then the reading of the potentiometer will be(a) 1.0138 V(b) 1.0183 V(c) (1.0138)2 / 1.0183 V(d) (1.0138)2 /V.Q5. The maximum phase shift that can be obtainedby using a lead compensator with transfer functionGc (s) =Is equal to:(a) Improve relative stability.(b) Increase the speed of response.(c) Increase bandwidth.(d) Increase overshoot.Q6. Storage of 1 KB means the following numberof bytes:(a) 1000(b) 964(c) 1024(d) 1064.Q7. Consider the following statements regardingthe circuit given in the figure, where the outputvoltageis constant:1. The voltage at which the Zener breaks down.

2. The difference between 1 and the current atwhich the Zener breaks down.3. The Zener nominal resistance.

Of these statements:(a) 1, 2 and 3 are correct.(b) 1 and 2 are correct.(c) 2 and 3 are correct.(d) 1 and 3 are correct.Q8. High intermediate frequency in a superheatreceiver(a) Increases tracking problems.(b) Reduces adjacent channel rejection.(c) Improves selectivity.(d) None of the above.Q9. In a 16-bit microprocessor, words are stored intwo consecutive memory locations. The entirewordcan be read in one operations provided the first(a) Word is even.(b) Word is odd.(c) Memory location is odd.(d) Memory address is even.Q10. Polythene is(a) A polymer of ethylene.(b) Vulcanized rubber.(c) Impregnated cotton.(d) Cellulose derivative.Q11. Above the Curie temperature, the hysteresisloop of a ferroelectric material can be described by

a(a) Inversely proportional to temperature andproportional to the square of the permanentdipole moment.(b) Proportional to temperature as well as to thesquare of the permanent dipole moment.(c) Proportional to temperature and inverselyproportional to the square of the permanentdipole moment.(d) Inversely proportional to temperature as well asto the square of dipole moment.Q12. A 3-phase step down transformer isconnected to 6.6 KV mains and takes 10A. For

which of thefollowing connection the secondary line currentwill be least?(a) DeltaDelta(b) StarStar(c) DeltaStar(d) StarDelta.Q13. In an induction motor, if the air gap isincreased(a) Speed will reduce.(b) Efficiency will improve(c) Power factor will improve(d) Breakdown torque will reduce.


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Q14. Which of the following are the features of ashaded pole motor?1. Salient-pole stator.2. Uniform air-gap3. Tow stator windings one of which is a short-circuited ring.4. Squirrel cage rotor.Select the correct answer using the codes givenbelow:

Codes:-(a) 1 and 3(b) 2 and 4(c) 1, 3 and 4(d) 1, 2 and 3Q15. In a synchronous machine in case the axis offield flux is in line with the armature flux, then(a) The machine is working as synchronous motor.(b) The machine is working as synchronousgenerator.(c) The machine is said to be floating.(d) The machine will vibrate violently.Q16. A cumulatively compound dc generator issupplying 20 a at 200 V. Now if the series fieldwinding isshort circuited, the terminal voltage will(a) Remain unaltered at 200 V(b) Rise to 220 V(c) Shoot up to a high value(d) Will reduce to 150 V.Q17. An ACSR conductor having 7 steel strandsand 24 aluminum conductor surrounding the steelstrands is called(a) 24 / 7 ACSR(b) 7 / 24 ACSR(c) 41 / 7 ACSR(d) 7 / 31 ACSR

Q18. The current through a series RL circuit iswhen excited by a unit impulse voltage.The values of R and L are respectively,(a) 8,4(b) 4,2(c) 2,4(d) 1,4Q19. The critical frequency of an ionosphere layeris 10 MHz. What is the maximum launching anglefrom the horizon for which a 20 MHz wave will bereflected by the layer?(a) 0(b) 30

(c) 45(d) 90Q20. A half- wave thyristor converter supplies apurely inductive load, as shown in Figure. If thetriggering angle of the thyristor is 120, the

extinction angle.(a) 240

(b) 180(c) 200(d) 120Q21. In the ac bridge shown in the figure

Z= 450 ohm,

Z= (300-j600) ohm,

Z

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