electrical ntpc

8/13/2019 Electrical NTPC

http://slidepdf.com/reader/full/electrical-ntpc 1/24

MODEL QUESTION PAPER NO.1

1) Steady state acceleration error of type 1 system,a. 0 b. 1c. Infinityd.

2) Position and velocity of type 2 system,

a. Constant, Infinity. b. Zero, Constant.c. Zero, Zero.d. Constant, Constant.

3) In a diode ‘cut-in’ & ‘forward voltage drop’ a. 0.7, 0.7 b. 0.7, 1c. 0.7, 0.6d. 1, 0.7

4) Potential value of α in a transistor? β a. 1.

b. 1.c. Negative.d. Between 0.95 & 0.99

5) What is the relation between α & β of a transistor? 6) In SCR dv/dt protection achieved by

a. RL in Series. b. RC across.c. L in series.d. RC in Series.

7) Placing inverter between both input of S-R Flip-Flop results in,a. J-K Flip Flop.

b. D Flip-Flop.c. T Flip-Flop.d. Master Slave J-K Flip-Flop.

8) Which have Max. Distortion?a. Class A Amplifier. b. Class B Amplifier.c. Class AB Amplifier.d. Class C Amplifier.

9) Which is Initial Value Theorem,4 options were there.

10) By increasing Frequency, power dissipation in CMOS,

a. reduce. b. Increase.c. Unchanged.

11) Anderson Bridge used to measurea. Inductance b. Capacitance.c.

d.12) Laplace transform of e-atsin wt.13)Lap winding is mostly suitable for

a. Low Voltage, High Current Machines.



b. High Voltage, High Current Machines.c. High Voltage, Low Current Machines.d. Low Voltage, Low Current Machines.

14) Turn-on time of SCR in Series with RL circuit can be reduced by,a. Increasing ckt resis. R. b. Decreasing ckt resis R.c. Increasing ckt ind. L.d. Decreasing ckt. Ind. L.

15) In Two-Wattmeter Method of measuring power, the reading of 2 W.M. will bea. VLILcos(30+φ), VLILcos(30+φ) b. VLILcos(30 –φ), VLILsin(30 –φ) c. VLILcos(30 –φ), VLILcos(30+φ) d. VLILcos(30 –φ), VLILsin(30+φ)

16) In Railways the CB used isa. SF6. b. ABCB.c. VCB.d. OCB.

17) What is the short-circuit admittance parameter Y11 of the following п-Network?

____________Yc____________| || |

Ya Yb| || |

18) What is 7483?4 options were given.

19) 8080 isa. 16 bit. b. 24 bit.

c. 64 bit.d. 32 bit.20) A question on 4 types of CRO with their application . You have to match them.21) Kirchoff’s Law is applicable for.

a. AC ckt. only. b. DC ckt. only.c. Both AC & DC ckt.d. Passive ckt. Only.

22) What is Synchronous Reactance?23) A Q was from DC M/c.; 4 type Generators(series, shunt, cumulative, ______ ) and their appl.(arc

welding, booster, ______, ______ ) Given, you have to match them.

24) Q came from II-quadrant operation of DC drive .25) An inverted sawtooth wave form was given which had (-)ve Y-axis magnitudeon 30 and time value onX-axis were 5 & 7.You have to choose the correct mathematical form of that wave from 4 options.

26) A simple ckt with a 20V source, a diode and a 10 Ohm resistance in series was given,The condition was 'if the diode is ideal' then what will be the current value?

27) Which is universal GATE?a. NAND & NOR. b. NAND.c. NOR.



MODEL QUESTION PAPER NO 2

1.differential relay is used for which type of protectiona) internal b)2.Type of CB's used in railway servicea)air blast b)SF6 c)vacuum d)oil3.L[e^-at .sinwt]4.what are the positional and velocity constants of a type 2 system

5.what type of compensation is made if a pole is added to T.F6.what are universal gatesa)NAND and NOR b)NAND c)NOR d)none of these.7.which f/f is formed if both the inputs of SR f/f are inverted.a)JK b)D c)T d)8. formula for initial value theorem9.how many circuits are to be solved in a super position theorema)equal to no of nodes b)no of sources...10.KVL is applied to which networksa)linear b)ac circuits c) dc circuits d )both ac and dc circuits11.A match the following about CRO's

p.storage croq.sampling cror.high fre. cros.low fre. cro12. A match the following about power plantsp.hydal 1.high initial costq.thermal 2.high maintainencer.nuclear 3.high operating costsdiesel 4.high life13.how the turn on time of an SCR can be reduced14A match the following about different scr's

p.triacq.gtor.rcts.15.how dv/dt triggering is applied to an scra) by using series RCb)placing RC across scrc)d)16.what are the values of cut in and forward voltage drops of a diodea)0.7v,0.7v

b)1v ,0.6v

17.alpha value range in a transistora)unity b)0.95 to 0.99 c)more than unity18.relation between alpha and beta in a transistor19.what is 7423a) full adder b)TTL adder c) 8 bit adder/subtractor20.A match the following about dc generatorsp. series 1.battery chargingq.shunt 2.booster



r.compound 3.transmissions.differential 4.arc welding21. A simple ckt with a dc voltage and a diode is connected to it FB conditon and a MI meter isconnected to it then asked about the amount of rms value of current shown by the multimeter22.

2nd section (35 bits)consists of general awareness (5 bits),aptitude(10) ,reasoning (10) ,comprehensionand grammatical mistakes(3)

general awareness 51.who donated land to golden temple at amritsara)akbar b)humayan c)shahjahan d)jahangir52.what is Fahrenheit 9/1153.who is christiano Ronaldo54. what a student should possess to participate in municipal council electionsaptitude blood relations -------1time and work ..........1about volume of a conebar chars and pie charts ..........5

reasoning serie completion of numbers ......2coding.........1non verbal reasoning ........3a no preceeding by some no and followed by bit ...1permutations and combinations .........3

MODEL PAPER NO 3

1. what is the use of 'aqudag'in cro?(a) .to absorb primary electrons (b).both primary and secondary (c)only secondary electrons2. modulation index in AM chnages from 0 to1 ,effect on transmitted power is-(a)no change (b)50% increase (c) (d)3.exp. for FM is given and asked to calculate modulation index and deviation.4.at a node ,sum of incoming current 5+j4 ,the outgoing will be..5.quantization error is related to..6.in satellite communication ,military use the access technique7.memeory mapped i/o and i/o mappedi/o has address lines8.12 bit address lines has memeory capacity9 .final value theorem experession.

10. ques .about 8085 flags.11. limitation of kiechoffs law .12. z-transform of unit step signal13. poission ratio given ,gauge factor asked14.FET can be used as...which device can be used as double SCR.

MODEL PAPER NO 4



Part - 1 , ( Technical)

1. What is ABC Analysis? - Inventory cost management2. What is farenheit 9 / 11 ? - A Micheal More,s Documentary film of 2004. They confused it otheroptions like unit of temp, device used to count the no of cells in body etc..3. What is Kaplan Turbine - A high head low discharge , Low head high discharge etc were the options.4. Chip formation occurs during which of the following conditions :

a) High speed low rake angle

b) Low speed High rake anglec) Low Lowd) High High

5. What is centrifugal Pump?6. Problems related to Speed of the Flywheel?7. Booting Information is stored in:

a) RAM b) ROM c) EPROM d) PROM

8. C 177 S - 6 denotes which type of fit? Options were clearance fit , Running Fit, Push Fit etc

9. Pre heating in welding is done for ?? - To prevent Cold cracks

10. Precautionary measures used in Welding?11. Problems on Efficiency of rankine cycle?12. Hook,s law MOSTLY applies for which of these materials? - Rubber , Plastic, carbon steel , Tungsten.13.When does Break Even Point occur?14. What is meant by Discretionary cost?15 .Methods to improve efficiency of heat Exchanger?16. NGL interferometer is used for??? ( A question from metrology)17. problems on Emissivity?

Part - 2

1. How do you Identify Cristiano Ronaldo?

2. Few questions on the following:a) Comprehensive passage reading,b) Bar chart interpretationc) Missing no,s in a seriesd) Coding of alphabetse) Permutation & combinationf) Gramatically Correcting a sentenceg) Arranging the bits of sentences in proper order which forms a meaningful storyh) Diagrams from the options which follows a particular sequence

MOCEL PAPER NO 5

TECHNICAL - Mechanical:

1.in centrifugal pump the discharge varies asspeed, square of speed ,root of speed ,inverse to speed

2.for welding what are the precautions need to be taken?

3.what is a-b-c analysis done for



4. what is a kaplan turbine ?

5.a numerical to find out sink temp ,efficiency was given nd source T was given

6.welding arc depends on ?

7.what is scheduling

8. what is concurrent engineering?

9.X=Fn.(t)

find the time when vel. is zero

10. a numerical on NTU...

11. A numerical on LMTD?

12.where is the program written for boot up of computera.RAM b. ROM c.PROM d. EPROM

13.A Numerical on thrmal power plant efficiency was given .

14.value of transmissibilty was to be found out if W/Wn is <1.414?

15.what is the value of velocity & accelaration nera bottom dead centre ?

16.a question on the format of nc machine if the point moves from one point to the other

17.a numerical on linear programming .

three constraints were given and you the maximu profit for eq 5X1 +2x2 was to be found out ?

18.if load on a beam is doubled what is the effect on bending moment ?

19.one nnumerical on emmisvity .

20.why preheating is done before welding?

21.TDS=dU+Pdv is used for :

friends i remember these questions only;

NON TECHNICAL

the questions here were a mix of apti reasoning and english ...

for this section nothing much to worry friends

this time there were 4 questions of general awareness.

1.who is chritiano ronaldo

2.what is fahrenheight 9/11?

3. which mughal emperor donated land in amritsar to build golden temple



4.economic liberalisation?

inenglish there was a easy passage and 4 questions on it ?

3 sentence correction

1 jubled up sentences

apti questions were from cone , men and work ,pricing

reasoning comprised of 3 questions where a certain pattern was shown in pictorial form nd you had findout the odd one out OR the next one which will continue the pattern

2 question on fill the series

1 question on blood relation

friends this section was easier and it did nt have any antonyms or synonyms

MODEL PAPER NO 6

1 A system has poles at 0.01 Hz, 1 Hz and 80 Hz; zeros at 5 Hz, 100 Hz and 200 Hz. The approximatephase of the system-response at 20 Hz isA) – 90°B) 0°C) 90°D) – 180°Answer : (A)

2 In an abrupt p-n junction, the doping concentrations on the p-side and n-side are NA = 9x 1016/cm3and ND = 1 x 1016/cm3 respectively. The p-n junction is reverse biased and the total depletion width is 3m m. The depletion width on the p-side isA) 2.7 mmB) 0.3 mm.C) 2.25 mmD) 0.75 mmAnswer : (B)

3 A master-slave flip-flop has the characteristic thatA) change in the input immediately reflected in the outputB) change in the output occurs when the state of the master is affectedC) change in the output occurs when the state of the slave is affectedD) both the master and the slave states are affected at the same timeAnswer : (C)

4 A parallel plate air-filled capacitor has plate area of l0-4 m2 and plate separation of 10-3 m. It is

connected to a 0.5 V, 3.6 GHz source. The magnitude of the displacement current is (e0 = 1/36p x 10-9F/m)A) 10 mAB) 100 mAC) 10 AD) 1.59 mAAnswer : (A)5 The phase velocity of an electromagnetic wave propagating in a hollow metallic rectangular waveguidein the TE10 mode isA)equal to its group velocityB) less than the velocity of light in free spaceC) equal to the velocity of light in free space



D) greater than the velocity of light in free spaceAnswer : (D)

6 Noise with uniform power spectral density of N0W/Hz is passed through a filter H (w) = 2 exp(-jwtd)followed by an ideal low pass filter of bandwidth BHz. The output noise power in Watts isA) 2N0BB) 4N0BC) eN0BD) 16 N0B

Answer : (B)

7 The cascade amplifier is a multistage configuration ofA) CC-CBB) CE-CBC) CB-CCD) CE-CCAnswer : (B)

8 Consider a lossless antenna with a directive gain of +6dB. If 1 mW of power is fed to it the total powerradiated by the antenna will beA) 4 mW

B) 1 mWC) 7 mWD) 1/4 mWAnswer : (A)

9 The bandgap of Silicon at room temperature isA) 1.3 eVB) 0.7 eVC) 1.1 eVD) 1.4 eVAnswer : (C)

10 In a PCM system, if the code word length is increased from 6 to 8 bits, the signal to quantization noiseratio improves by the factorA) 8/6B) 12C) 16D) 8Answer : (C)

11 A device with input x(t) and output y(t) is characterized by: y(t) = x2(t). An FM signal with frequencydeviation of 90 kHz and modulating signal bandwidth of 5 kHz is applied to this device. The bandwidth ofthe output signal isA) 370 kHzB) 190 kHz

C) 380kHzD) 95kHzAnswer : (C)

12 For the polynomial P(s) = s5 + s4 + 2s3 + 2s2 + 3s + 15, the number of roots which lie in the righthalf of the s-plane isA) 4B) 2C) 3D) 1Answer : (B)



13 An AM signal is detected using an envelope detector The carrier frequency and modulating signalfrequency are 1 MHz and 2 kHz respectively. An appropriate value for the time constant of the envelopedetector isA) 500 msecB) 20 msecC) 0.2 msecD) 1 msecAnswer : (B)

14 In a PCM system, if the code word length is increased from 6 to 8 bits, the signal to quantization noiseratio improves by the factorA) 8/6B) 12C) 16D) 8Answer : (C)

15 Consider the following statements S1 and S2.S1: The b of a bipolar transistor reduces if the base width is increased.S2: The b of a bipolar transistor increases if the doping concentration in the base is increased. Which oneof the following is correct?

A) S1 is FALSE and S2 is TRUEB) Both S1 and S2 are TRUEC) Both S1 and S2 are FALSED) S1 is TRUE and S2 is FALSEAnswer : (D)

16. A digital-to-analog converter with a full-scale output voltage of 3.5 V has a resolution close to 14m V.Its bit size isA) 4B) 8C) 16D) 32

Answer : (B)

17. A single-phase half-controlled rectifier is driving a separately excited dc motor. The dc motor has aback emf constant of 0.5 V/rpm. The armature current is 5 A without any ripple. The armature resistanceis 2W. The converter is working from a 280 V, single phase ac source with a firing angle of 80°. Under thisoperating condition, the speed of the motor will beA) 339 rpmB) 359 rpmC) 366 rpmD) 386 rpmAnswer : (C)

17. In relation to the synchronous machines, which one of the following statements is false?A) In salient pole machines, the direct-axis synchronous reactance is greater than the quadrature-axissynchronous reactanceB) The damper bars help the synchronous motor self startC) Short circuit ratio is the ratio of the field current required to produce the rated voltage on open circuitto the rated armature currentD) The V-curve of a synchronous motor represents the variation in the armature current with fieldexcitation, at a given output powerAnswer : (C)

18. A parallel plate air-filled capacitor has plate area of l0-4 m2 and plate separation of 10-3 m. It isconnected to a 0.5 V, 3.6 GHz source. The magnitude of the displacement current is (e0 = 1/36p x 10-9



F/m)A) 10 mAB) 100 mAC) 10 AD) 1.59 mAAnswer : (A)

19 The 8085 assembly language instruction that stores the content of H and L registers into the memorylocations 2050H and 2051H, respectively, isA) SPHL 2050H B) SPHL2051H C) SHLD 2050H D) STAX 2050H Answer : (C)

20 If E is the electric field intensity, Ñ(Ñ x E ) is equal toA) EB) | E |

C) null vectorD) zeroAnswer : (D)

21 The insulation strength of an EHV transmission line is mainly governed byA) load power factorB) switching over-voltagesC) harmonicsD) coronaAnswer : (B)

22.The Q – meter works on the principle of

A) mutual inductanceB) self inductanceC) series resonanceD) parallel resonanceAnswer : (C)

23.A 800 kV transmission line is having per phase line inductance of 1.1 mH/km and per phase linecapacitance of 11.68 nF/km. Ignoring the length of the line, its ideal power transfer capability in MW isA) 1204 MWB) 1504 MWC) 2085 MWD) 2606 MWAnswer : (C)

24.In a PCM system, if the code word length is increased from 6 to 8 bits, the signal to quantization noiseratio improves by the factorA) 8/6B) 12C) 16D) 8Answer : (C)

25. At an industrial sub-station with a 4 MW load, a capacitor of 2 MVAR is installed to maintain the loadpower factor at 0.97 lagging. If the capacitor goes out of serivce, the load power factor becomesA) 0.85



B) 1.00C) 0.80 lagD) 0.90 lagAnswer : (C)

26. The conduction loss versus device current characteristic of a power MOSFET is best approximated byA) a parabolaB) a straight lineC) a rectangular hyperbola

D) an exponentially decaying functionAnswer : (A)

27. High Voltage DC (HVDC) transmission is mainly used forA) bulk power transmission over very long distancesB) inter-connecting two systems with the same nominal frequencyC) eliminating reactive power requirement in the operationD) minimizing harmonics at the converter stationsAnswer : (A)

28. For the equation,s3 – 4s2+ s + 6 = 0

the number of roots in the left half of s-plane will be

A) 0B) 1C) 2D) 3Answer : (C)

29. For the function f(x) = x2 e-x, the maximum occurs when x is equal toA) 2B) 1C) 0D) -1Answer : (B)

29.The drain of an n-channel MOSFET is shorted to the gate so that VGS = VDS. The threshold voltage(VT) of MOSFET is 1 V. If the drain current (ID) is 1 mA for VGS = 2V, then for VGS = 3V, ID isA) 2 mAB) 3 mAC) 9 mAD) 4 mAAnswer : (D)

30. The first and the last critical frequency of an RC-driving point impedance function must respectivelybe

A) a zero and a poleB) a zero and a zeroC) a pole and a poleD) a pole and a zeroAnswer : (D)

31. In what range should Re(s) remain so that the Laplace transform of the function e (a+2)t+5 exits?A) Re (s) > a + 2B) Re (s) > a + 7C) Re (s) < 2D) Re (s) > a + 5Answer : (A)



32.A parallel plate air-filled capacitor has plate area of l0-4 m2 and plate separation of 10-3 m. It isconnected to a 0.5 V, 3.6 GHz source. The magnitude of the displacement current is (e0 = 1/36p x 10-9F/m)A) 10 mAB) 100 mAC) 10 AD) 1.59 mAAnswer : (A)33.For the polynomial P(s) = s5 + s4 + 2s3 + 2s2 + 3s + 15, the number of roots which lie in the right

half of the s-plane isA) 4B) 2C) 3D) 1Answer : (B)

34. The phase velocity of an electromagnetic wave propagating in a hollow metallic rectangular waveguidein the TE10 mode isA) equal to its group velocityB) less than the velocity of light in free spaceC) equal to the velocity of light in free spaceD) greater than the velocity of light in free spaceAnswer : (D)

35.A device with input x(t) and output y(t) is characterized by: y(t) = x 2(t). An FM signal with frequencydeviation of 90 kHz and modulating signal bandwidth of 5 kHz is applied to this device. The bandwidth ofthe output signal isA) 370 kHzB) 190 kHzC) 380kHzD) 95kHzAnswer : (C)

36. The Q – meter works on the principle of

A) mutual inductanceB) self inductanceC) series resonanceD) parallel resonanceAnswer : (C)

37. The Fourier transform of a conjugate symmetric function is alwaysA) imaginaryB) conjugate anti-symmetricC) realD) conjugate symmetricAnswer : (C)

38. An ideal op-amp is an idealA) voltage controlled current sourceB) voltage controlled voltage sourceC) current controlled current sourceD) current controlled voltage sourceAnswer : (B)

q-1 A circuit has a resistance of 11 W, a coil of inductive reactance 120 W, and a capacitor with a 120-Wreactance, all connected in series with a 110-V, 60-Hz power source. What is the potential differenceacross each circuit element?



A) (a) VR = 110 V, (b) VL = VC = 1.2 KvB) (a) VR = 120 V, (b) VL = VC = 2.4 kVC) (a) VR = 4.8 V, (b) VL = VC = 0 kVD) (a) VR = 5.0 V, (b) VL = VC = 8.0 V

Q-2 Applying DeMorgan’s theorem to the expression , we get

A) (A+B)+CB) A(B + C)

C) Both A & BD) None of above

Q-4 Refer Below figure to Determine the resonant frequency…

A) 123.4 kHzB) 61.7 kHzC) 45.97 kHzD) 23.1 kHz

Q-4 Express the decimal number 57 in binary.

A) 100101B) 111010C) 110010D) 111001

Q-5 A vertical electric dipole antenna

a) radiates uniformly in all directions.b) radiates uniformly in all horizontal directions, but more strongly in the vertical direction.c) radiates most strongly and uniformly in the horizontal directionsd) does not radiate in the horizontal directions

Q-6 A particle oscillates according to the equation y=5.0 cos 23 t, where y is in centimeters. Find itsfrequency of oscillation and its position at t=0.15 s.

a) f = 23 Hz, y = -4.8 cmB) f = 3.7 Hz, y = -5.0 cmC) f = 3.7 Hz, y = -4.8 cmD) f = 3.7 Hz, y = +4.8 cm

Q-7 A 10.0-µF capacitor is in series with a 40.0-W resistance, and the combination is connected to a 110-V, 60.0-Hz line. Calculate (a) the capacitive reactance, (b) the impedance of the circuit, (c) the current inthe circuit, (d) the phase angle between current and supply voltage

A) (a) 0.0038W (b) 305W (c) 0.415 A (d) voltage lags by 8.58°B) (a) 266W (b) 269W (c) 0.409 A (d) voltage lags by 81.4°C) (a) 16 kW (b) 72 kW (c) 2.75 A (d) voltage lags by 6.63°D) (a) 2.6 kW (b) 262W (c) 0.256 MA (d) voltage leads by 81.4°

Q-8 A circuit has a resistance of 11 W, a coil of inductive reactance 120 W, and a capacitor with a 120-Wreactance, all connected in series with a 110-V, 60-Hz power source. What is the potential differenceacross each circuit element?

A) (a) VR = 110 V, (b) VL = VC = 1.2 KvB) (a) VR = 120 V, (b) VL = VC = 2.4 kV



C) (a) VR = 4.8 V, (b) VL = VC = 0 kVD) (a) VR = 5.0 V, (b) VL = VC = 8.0 V

Q-9 What is the primary function of multiplexing?

A ) To match the frequency range of a signal to a particular channel.B ) To reduce the bandwidth of a signal.C ) To select one radio channel from a wide range of transmitted channels.D ) To allow a number of signals to make use of a single communications channel.

Q-10 A second step to further increase system capacity is a digital access method called TDMA (TimeDivision Multiple Access). Using the same frequency channelization and reuse as FDMA analog but addinga time sharing element, the effective capacity is:

A) DoubledB) TripledC) Reduced by one thirdD) Unchanged

Q-11 What are Pseudo-Random noise sequences, or P/N Sequences?

A) P/N Sequences are known sequences which exhibit the properties or chracteristics of randomsequencesB) P/N Sequences can be used to logically isolate users on the same physical (frequency) channelC) P/N Sequences appear as random noise to everyone else, except to the transmitter and intendedreceiverD) All of the above

Q-12 An op-amp integrator has a square-wave input. The output should be

A ) a sine wave.B) a triangle waveC) a square wave.

D) pure DC.

Q-13 What is the relationship between the series and parallel resonant frequencies of a quartz crystal?

A) They are equal.B) Parallel resonant frequency is approximately 1 kHz higher than series resonant frequencyC) Series resonant frequency is approximately 1 kHz higher than parallel resonant frequency.D) none of the above

Q-14 Refer Below figure to Determine the resonant frequency…

A) 123.4 kHz

B) 61.7 kHzC) 45.97 kHzD) 23.1 kHz

Q-15 Which FET amplifier(s) has (have) a phase inversion between input and output signals?

A) common-gateB) common-drainC) common-sourceD) all of the above



section -1 b.

1. The order of the differential equation 2 3 4 t 2 d y dy y e

dt dt _ _ − + _ _ + = _ _ is

(A) 1 (B) 2 (C) 3 (D) 4

2. The Fourier series of a real periodic function has only P. Cosine terms if it is even Q. Sine terms if it is even R. Cosine terms if it is odd

S. Sine terms if it is odd Which of the above statements are correct? (A) P and S (B) P and R (C) Q and S (D) Q and R

3. A function is given ( ) 2 f t = sin t + cos2t. Which of the following is true? (A) f has frequency components at 0 and 1/2p Hz (B) f has frequency components at 0 and 1/p Hz (C) f has frequency components at 1/2p and 1/p Hz (D) f has frequency components at 0, 1/2p and 1/p Hz

4. A fully charged mobile phone with a 12V battery is good for a 10minute talktime. Assume that, during the talk-time, the battery delivers a constant current of 2A and its voltage drops linearly from 12 V to 10V as shown in the figure. How much energy does the battery deliver during this talk-time?

(A) 220J (B) 12kJ (C) 13.2kJ (D) 14.4kJ

5. In an n-type silicon crystal at room temperature, which of the following can have a concentration of 19 3 4 ×10 cm− ? (A) Silicon atoms (B) Holes (C) Dopant atoms (D) Valence electrons

6. The full form of the abbreviations TTL and CMOS in reference to logic families are (A) Triple Transistor Logic and Chip Metal Oxide Semiconductor (B) Tristate Transistor Logic and Chip Metal Oxide Semiconductor 10min t 0 10V 12V v (t)



(C) Transistor Transistor Logic and Complementary Metal Oxide Semiconductor (D) Tristate Transistor Logic and Complementary Metal Oxide Silicon

7. The ROC of Z-transform of the discrete time sequence ( ) ( ) ( ) n n 1 1

x n u n u n 1 is 3 2 _ _ _ _ = _ _ − _ _ − − _ _ _ _ (A) 1 1 z 3 2 < < (B) 1

z 2 > (C) 1 z 3 < (D) 2 < z < 3

8. The magnitude plot of a rational transfer function G(s) with real coefficients is shown below. When of the following compensators has such a magnitude plot?

(A) Lead compensator (B) Lag compensator (C) PID compensator (D) Lead-lag compensator

9. A white noise process X(t) with two-sided power spectral density 1×10-10 W/Hz is input to a filter whose magnitude squared response is shown below The power of the output process Y(t) is given by

(A) 7 5 ×10− W (B) 6 1×10− W (C) 6 2 ×10− W (D) 5 1×10− W

10. Which of the following statements is true regarding the fundamental mode of the metallic waveguides shown?

(A) Only P has no cutoff-frequency (B) Only Q has no cutoff-frequency (C) Only R has no cutoff-frequency (D) all three have cutoff-frequency P. Coaxial Q. Cylindrical R:Rectangular −40dB 20dB G(jw) logw −10kHz 10kHz 1 ( )2



H f X(t) Y (t) F

11. A fair coin is tossed 10times. What is the probability that ONLY the first two tosses will yield heads? (A)

2 1 2 _ _ _ _ _ _ (B) 2 10 2 1

C 2 _ _ _ _ _ _ (C) 10 1 2 _ _ _ _

_ _ (D) 10 10 2 1 C 2 _ _ _ _ _ _

12. If the power spectral density of stationary random process is a sine-squared function of frequency, the shape of its autocorrelation is (A) (B) (C) (D) 13. ( ) ( ) 1 0 1 unit circle 1 f z If f z c c z , then dz is given by



z − + = + __

(A) 2pc1 (B) ( ) 0 2p 1 + c (C) 1 2pjc (D) ( ) 0 2pj 1 + c

14. In the interconnection of ideal sources shown in the figure, it is known that the 60V source is absorbing power Which of the following can be the value of the current source _ ?

(A) 10A (B) 13A (C) 15A (D) 18A

15. The ratio of the mobility to the diffusion coefficient in a semiconductor has the units

(A) 1 V− (B) 1 em× V− (C) 1 V × cm− (D) V . s

16. In a microprocessor, the service routine for a certain interrupt starts from a fixed location of memory which cannot be externally set, but the interrupt can be delayed or rejected. Such an interrupt is (A) non-maskable and non-vectored (B) maskable and non-vectored (C) non-maskable and vectored (D) maskable and vectored

_ +− 60V 12A + − 20V R (t) t R (t) t R (t) t

R (t) t

17. If the transfer function of the following network is ( ) ( ) 0 i V s 1 V s 2 s CR =

+ The value of the load resistance RL is (A) R/4 (B) R/2 (C) R (D) 2R

18. Consider the system dx Ax Bu with A 1 0 and B p dt 0 1 q = + = _ = _ _ _ _ _ where p and q are arbitrary real numbers. Which of the following statements about the controllability of the system is true?



(A) The system is completely state controllable for any nonzero values of p and q (B) Only p=0 and q=0 result in controllability (C) The system is uncontrollable for all values of p and q (D) We cannot conclude about controllability from the given data

19. For a message signal ( ) ( ) m m t = cos 2pf t and carrier of frequency fc, which of the following represents a single side band (SSB) signal?

(A) ( ) ( ) m c cos 2pf t cos 2pf t (B) ( ) c cos 2pf t (C) ( ) c m cos __2p f + f t (D) ( ) ( ) m c __1 + cos 2pf t cos 2pf t

20. Two infinitely long wires carrying current are as shown in the figure below. One wire is in the y-z plane and parallel to the y-axis. The other wise is in the x-y plane and parallel to the x-axis. Which components of the resulting magnetic field are non-zero at the origin? (A) x, y, z components (B) x, y components (C) y, z components (D) x, z components R

C i V + − 0 V + − L R 1A 1A z

x y

21. Consider two independent random variables X and Y with identical distributions. The variables X and Y take values 0, 1 and 2 with probabilities 1 1 1 , and 2 4 4 respectively. What is the conditional probability P (X + Y = 2| X − Y = 0) ? (A) 0 (B)

1 16 (C) 1 6 (D) 1

22. The Taylor series expansion of sinx at x is given by



x = p − p (A) ( )2 x 1 ... 3! − p

+ + (B) ( )2 x 1 ... 3! − p − − + (C) ( )2 x 1 ... 3! − p − + (D)

( )2 x 1 ... 3! − p − + +

23. If a vector field V __ is related to another vector field A __

through V = Ñ × A, __ __ which of the following is true? Note: C and SC refer to any closed contour and any surface whose boundary is C. (A) C C S _ V × d = __ A × dS __ ___ __ ____ _ _ (B) C C S

_ A × d = __ V × dS __ ___ __ ____ _ _ (C) C C S _ Ñ × V × d = __ Ñ × A × dS __ ___ __ ____ _ _ (D) C C S _ Ñ × A × d = __ V × dS __ ___ __ ____



_ _

24. Given that F(s) is the one-sided Laplace transform of f(t), the Laplace transform of ( ) t 0 _ f t dt is

(A) sF (s) − f (0) (B) ( ) 1 F s s (C) ( ) s 0 _ F t dt (D) ( ) ( ) 1 F s f 0 s __ −

25. Match each differential equation in Group I to its family of solution curves from Group II. Group – I Group – II P. dy y dx x = 1. Circles Q. dy y

dx x = − 2. Straight lines R. dy x dx y = 3. Hyperbolas S. dy x dx y = − (A) P-2,Q-3,R-3,S-1 (B) P-1,Q-3,R-2,S-1

(C) P-2,Q-1,R-3,S-3 (D) P-3,Q-2,R-1,S-2

26. The eigen values of the following matrix are -1 3 5 -3 -1 6 0 0 3 _ _ _ _ _



(A) 3,3 + 5j,6 − j (B) −6 + 5j,3 + j,3 − j (C) 3 + j,3 − j,5 + j (D) 3, −1 + 3j, −1 − 3j

27. An AC source of RMS voltage 20V with internal impedance ( ) S Z = 1 + 2j W feeds a load of impedance ( ) L Z = 7 + 4j W in the figure below. The reactive power consumed by the load is

(A) 8VAR (B) 16VAR (C) 28VAR (D) 32VAR

28. The switch in the circuit shown was on position a for a long time, and is moved to position b at time t=0. The current i(t) for t>0 is given by (A) 125t ( ) 0.2e u t mA − (B) 1250t ( ) 20e u t mA − (C) 1250t ( ) 0.2e u t mA − (D) 1000t ( ) 20e u t mA − ( ) L Z = 7 + 4j W ( ) S Z = 1 + 2j W 20Ð0ºV +− +− 5kW

i (t)

MODEL PAPER NO 7

1. What is causal system?

2. Shunt reactor is used in EHV transmission line for

3. 20w, 40W, & 200w lamps are connected to three phases if neutral wire breaks then which lamp will

fuse first? 1) 20 2)40 3)200 three lamps will fuse together.

4. Synchronous machine can be operated at both lagging and leading power factor

5 What does synchronous speed mean?

6. Frequency of emf generated per rotation of rotor is equal to….

7. DC machine having wave winding is wounded as lap winding what will be the effect on emf generated

8 Which is remain unchanged in transformer action?

9. In transformer windings are connected………….?

10. In general how transformer is rated?

11. What is given on the name plate of motor? 1) KW 2) KVA 3) output shaft power

12. Short circuit test of transformer gives what?

13. Transformer core are laminated for what purpose?

14. What is supply voltage for heavy industry .1) 33KV 2) 11KV 3) 132 KV 4) 66KV 15. Basic structure SCR as a two transistor i.e. how they are connected?

16. What is Triac?

17. System admittance is (G+jB) what is reactive power absorbed if the voltage is V KV? (1) V (square)*B

(2) V (square)*g ….

18. In series R-L circuit what is phase difference between the voltage drop across R and L?

19. Power factor is cosine (delta ) delta is the angle between 1) phase voltage phase current 2)

Line voltage lone current 3) phase voltage line current 4) line voltage phase current.

20. Laplace of exp (-at)?



21. For series R-L-C circuit the load will be capacitive if the frequency is 1) greater than the resonant

frequency 2) less than the resonant frequency 3)….

22. In Wien’s bridge which circuit elements determine the frequency range?

23. What is the output if two booster having duty cycle K and (K-1) are connected in series?

24. If a DC shunt motor is loaded from unloaded condition what will be effect of on terminal voltage?

25. A second wire system having one pole one right half of the s-plane. When the system will be stable?

26. A system having repetitive pole what will be effect on the gain at the cross over frequency?

27. Hollow conductor is used to reduce corona loss how does it reduce the loss?

28. In DC machine how voltage is related to flux?

29. Nature of current and voltage in the armature and at the terminal in DC machine.

30. Motor acts on the principle of …………..rule

31. Which instrument measure both ac and dc?

32. How the rotation of induction motor is reversed?

33. If 3-phaseof a 3- phase balance load are reversed what will be the effect on the line current?

34. If the rating of VAR absorber is 50MVAR at 400KV. What will the VAR absorbed by the absorber at

300KV?

35. In regenerative breaking of DC series motor what is done?

36. Definitions of Fourier transform?

37. Laplace of f(t) is F(S) what is Laplace of f(t+T) . 38. Z-transform of sampled function x(n) for n>0.

39. Laplace transform of impulse function.

40. Z-transform of unity.

41. How many slip rings are there in 3phase synchronous motor?

42. How the speed of synchronous motor is controlled?

43. Speed control of induction motor?

44. When power supply is supplied to heater coil it glows while simple wire does not glow. Why?

45. A synchronous generator having inertia constant 4 and having rating of 100MVA. What will be energy

stored by the machine?

46. A transformer having ratio 20:1. The secondary load is 0.6 ohm and the voltage across it is 6 V whatwill be the primary current?

47. A RC circuit having r=0.8ohm, c=2.5micofarad what will be the time constant?

48. Find load impedance if c=0.1 micro farad?

49. Two capacitors connected in series the equivalent capacitance is 0.03uf and when connected in

parallel the equivalent capacitance is 0.16uf find out the ratio of the two capacitance?

50. An L-c circuit having frequency 1/sqrt (LC) what will the equivalent impedance?

51. An inverting op-am having input with resistance in series and a capacitance in feedback operates as

a……………….?

52. A current having fundamental and third harmonics what will be the rms value of the current?

53. Peak to peak value of voltage if rms voltage is 100V.

54. Rms voltage.

55. What is the approx efficiency of nuclear power plant?

56. What is the average current of a single phase full wave rectifier firing at angle alpha?

57. What is the function of freewheeling diode?

58. When SCR stops conduction? (holding current)

59. For measuring current why shunt resistance is used?

60. For economic operation of plant what is the condition?(taking into account the penalty factor)

61. Incremental fuel cost of two plants is given and a load is given. Find out the load sharing for economic

operation of the plant?



62. A two port network is represented by ABCD parameters. What will be condition for the two port

network to be symmetrical?

63. Size of the conductor is determined by ……………….

64. Which Surface is suitable for grounding?

1) Definition of synchronuous speed2) Steady state error formula3) Maths: Questions related to laplace, Z- transforms, and Forier series.. were asked

4) What is the transmisssion voltage for the bulk industries..5) Questions related to power plant applications and construction6) Electronics: from IGBTS, JFETS, BJT as mentioned above7) And also questions related to instrumentation were also asked

electrical ntpc

Documents