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click here for freelancing tutoring sitesBSNL TTA Question Paper: Network Filters and Transmission LinesExam Name: TTA (Telecom Technical Assistant)Specialization: Section C - Network Filters and Transmission LinesSection (Network Filters and Transmission Lines)1. Pick up wrong statement(a) A group of interconnected individual components known as circuit elements is called a network.(b) A humped network is an arrangement of physically separate resistors, inductors and capacitors.(c) Distributed network is one, which the resistive, inductive and capacitive effects are inseparable for network analyses.(d) A branch is a network having four elements. 2. Kirchoff’s laws for networks are:(a) The algebraic sum of branch currents meeting at any node is zero.(b) The algebric sum of voltage drops in any set of branches forming a closed circuit or loop must be equal to zero.(c) Both (a) and (b)(d) Neither (a) and (b) 3. Mutually coupled circuit is a circuit which is:(a) Bilateral(b) Unilateral(c) None of these(d) Either (a) or (b) 4. Duality is a(a) Transformation in which current and voltages are interchanged

(b) Active sources become passive sources(c) Passive sources become active sources(d) Both (b) and (c) 5. Combined inductance of two inductors L1 and L2 connected and voltages are interchanged(a) L1 + L2(b) (L1 + L2)/ L1(c) (L1 + L2) / (L1 X L2)(d) (L1 X L2) / (L1 + L2) 6. Normal analysis techniques are based on(a) Thevenin’s theorem(b) Tellegan’s theorem(c) Superposition theorem(d) Kirchoff’s Law 7. Two voltage sources can be connected in parallel when they are equal in(a) Magnitude(b) Frequency(c) Phase(d) All the above 8. The kirchoff’s law fail in(a) Linear circuits(b) Non-linear circuits(c) Lumped parameter circuits(d) Distributed parameter circuits 9. Which of the following is a nonreciprocal network ?(a) A network consisting of all resistances(b) A network consisting of all capacitances(c) A network consisting of all inductances(d) A transistor model 10. When two systems obey equations of the same form the systems are said to be(a) Similar system(b) Identical system(c) Analogous system(d) Digital system 11. For a highly selective circuit(a) It must have large value of Q(b) It must have high value of capacitance to produce resonance at fixed frequency(c) Either (a) or (b)(d) Neither (a) nor (b)

12. A network consisting of four terminals is called a(a) One port network(b) Two port network(c) Four port network(d) None of the above 13. Driving point of a network is(a) A port where voltage or current source is connected(b) A terminal where load is connected(c) A port where load is connected(d) None of the above 14. Ceramic filters are similar in construction to(a) Crystal filters(b) Crystal ladder filters(c) Crystal lattice(d) Mechanical filters 15. When two port networks are connected in parallel the resultant(a) Z parameters are the some of individual parameters(b) Y- parameters are the some of individual parameters(c) Both (a) and (b)(d) Neither (a) nor (b) 16. Electric wave filters(a) Allow electric signals with specified frequency range(b) Suppress signals outside a specified range(c) Both (a) and (b) occurs simultaneously(d) Either (a) or (b) occur at a time 17. A cascade connection of low pass filter and high pass filter is called(a) Band pass filter(b) Band elimination filter(c) Neither (a) nor (b)(d) Both (a) and (b) 18. The response of a network is decided by the location of(a) Its poles(b) Its zeros(c) Either (a) nor (b)(d) Both (a) and (b) 19. Example of two port network is(a) Transformer(b) Transmission line(c) Bridge circuit and transistor circuit(d) All of the above 20. The circuit whose properties are same in either direction is called(a) Universal circuit

(b) Reversible circuit(c) Unilateral circuit(d) Bilateral circuit 21. Distortion in transmission line is due to(a) Delay distortion(b) Phase distortion(c) Frequency distortion(d) All the above 22. The general parameters distributed along a transmission line are(a) R&L only(b) L&C only(c) C&G only(d) R, L, C&G 23. Phase distortion is prominently caused by(a) circuit transients(b) non linear characteristics(c) linearity(d) none 24. The voltage or current from the receiving end towards the sending end, decreasing in amplitude with increasing distance from the load is called(a) incident wave(b) medium wave(c) reflected wave(d) none of above 25. E.M. Waves of UHF is propagated efficiently via(a) parallel wire transmission lines(b) open wire transmission lines(c) wave guides(d) coaxial cables 26. Norton theorem is valid for network containing only(a) linear elements(b) no linear elements(c) resistance(d) reactance 27. The maximum power is absorbed by one network from other, joined to it at two terminals when the impedance of one is(a) complex conjugate of other(b) square root of other(c) same as other(d) none of above 28. The decrease in effective conductor cross section at high frequencies(a) decrease the conductor resistance(b) increase the conductor resistance(c) no change in conductor resistance

(d) none of above 29. Voltage standing wave ratio lies in the range(a) 0 to 1(b) 1 to infinity(c) 0 to infinity(d) -1 to +1 30. Attenuators have applications(a) in AC circuits only(b) in DC circuits only(c) in AC as well DC circuits(d) in low frequency circuits only 31. In an network(a) the number of tree branches is equal to the number of links(b) the number of tree branches cannot be equal to the number of links(c) the number of tree branches has no relation with the number of links branches(d) none of these 32. In open line transmission systems, attenuation is more at(a) lower frequencies(b) medium frequencies(c) higher frequencies(d) remains constant 33. a power ratio 100 is equivalent to(a) 10 dB(b) 20 dB(c) 50 dB(d) 100 dB 34. The velocity factor for small widely spaced conductors such as open wire line in air is very nearly(a) 0.66(b) 0.98(c) 0.82(d) 0.76 35. Transmission of power to a load over a transmission line achieves optimum value when standing wave ratio (SWR) becomes(a) 2 : 1(b) 1 : 2(c) 1 : 1(d) 1 : 10 36. The VSWR in a short circuited loss less transmission line equals(a) infinity(b) unity(c) zero(d) none of above

37. The velocity factor of a transmission line(a) is always greater than unity(b) depend upon the permittivity of the surrounding medium(c) is lease for air medium(d) is governed by skin effect 38. Which of the following is not correct(a) voltage source is an active element(b) current source is a passive element(c) resistance is a passive element(d) conductance is a passive element 39. A network is said to be nonlinear if it does not satisfy(a) superposition condition(b) homogeneity condition(c) both superposition and homogeneity conditions(d) associative condition 40. An capacitor with zero initial condition at t = 0+ act as a(a) short circuit(b) open circuit(c) current source(d) voltage source 41. An inductor stores energy in(a) electrostatic field(b) electromagnetic field(c) magnetic field(d) core 42. In series LCR circuits, at resonance,(a) current is maximum, power factor is zero(b) current is maximum, power factor is unity(c) current is minimum, power factor is unity(d) none of above 43. In an RCL series circuit, during resonance, the impedance will be(a) zero(b) minimum(c) maximum(d) none of above 44. When a source is delivering maximum power to load, the efficiency of the circuit is always(a) 50%(b) 75%(c) 100%(d) None of above 45. In a linear network, when the ac input is doubled, the ac output becomes(a) two times

(b) four times(c) half(d) one forth 46. A passive network has(a) current sources but no voltage sources(b) voltage sources but no current sources(c) both current and voltage sources(d) no voltage or current sources 47. Two resistances are connected in parallel and each dissipates 50 waits. The total power supplied by the source is(a) 25 watts(b) 50 watts(c) 100 watts(d) 200 watts 48. Three bulbs of 60 watts each are connected is parallel across 220v, 50 Hz supply. If one bulb burns out(a) only remaining two will operate(b) remaining two will not operate(c) all of three will operate(d) there will be heavy current from the supply 49. The amplitude of an audio signal is 10 and that of carrier wave is 50. Percentage modulation is:(a) 0.2(b) 20(c) 5(d) 60 50. The main advantage of PCM system is:(a) lower bandwidth(b) lower power(c) lower noiseSample Question Paper - BSNL TTA ExamPaper - II (Basic Engineering) BSNL TTA Exam1. X2 - 4X - 2Y + Y2 = 4 represents a circle with(a) radius = 3(b) radius = 4(c) radius = 2(d) radius = 52. Which of these represent two parallel lines:(a) Y - 4X - 4 = 0(b) Y + AX - 4 = 0(c) Y - 4X - 1 =0(a) (i) and (ii)(b) (i) and (iii)(c) (ii) and (iii)(d) None of these.

3. The conjugate of complex numbers 3 + 2j is(a) 3 - 2j(b) 2 + 3j(c) 2 - 3j(d) 3 + 4j4. A Square matrix each of whose diagonal element is 1 and each of the non-diagonal element is zero is called(a) Null matrix(b) Unit matrix(c) Diagonal matrix(d) Orthogonal matrix5. The determinant of matrix <image> is(a) 1(b) 9(c) 15(d) 216. The charge of an electron is equal to(a) 1.6 x 10-16 C(b) -1.6 x 10-16 C(c) 1.6 x 1019 C(d) -1.6 x 1019 C7. The potential energy of a charged conductor is(a) 1/2 CV2(b) 1/2 QV(c) Both (a) and (b)(d) None of these8. Capacitors are mainly used in(a) Electrical instruments(b) Storage of electrical energy(c) Overcoming voltage fluctuations(d) All the above9. Two capacities of 4 µF and 12 µF are joined in parallel. The total capacitance is(a) 8 µF(b) 16 µF(c) 3 µF(f) 2 µF10. What is the total resistance between points 'A' and 'B' in the given circuit<image>(a) 12/7 O(b) 15 O(c) 7 O(d) 7/12 O11. A current of 12 A is passing through a pure resistive circuit when the potential difference of 60 volts is applied across it, if the potential difference applied is reduced to 12 V, the current would be(a) 12/5 A(b) 60 A(c) 12 A(d) 2 A12. Which of these normally used household electrical bulbs will be having maximum resistance.(a) 100 Watt bulb

(b) 50 Watt bulb(c) 200 Watt bulb(d) 25 Watt bulb13.The distance of point P (4, 3) from the origin will be(a) 7(b) 1(c) 5(d) 914. The slope of the line passing from points (7, 3) and (5, 1) is(a) 1(b) 2(c) 3(d) 415. A line perpendicular to line 3x + 4y + 5 = 0 can be(a) 4x + 3y + 4 = 0(b) 4x - 3y + 3 = 0(c) 3x - 4y + 5 = 0(d) 3x - 4y + 2 = 0.16. The centre of the circle x2 + 6x - 4y + y2 + 12 = 0 will be at(a) (-3, 2)(b) (3, -2)(c) (-2, 3)(d) (2, -3)17. The product of (3 + 4j) and its conjugate is(a) 7(b) 25(c) 12(d) 2118. During charging of a lead acid cell, the specific gravity of electrolyte will(a) Increase(b) Decrease(c) Remain constant(d) Increase then Decrease19. The decimal number '12' is represented in binary system as(a) 1100(b) 0110(c) 1010(d) 111020. What is the value of current that will flow when a p. d. 200 V is applied across a circuit of 50 O resistance?(a) 4 A(b) 0.4 A(c) 10 A(d) 1 A21. If both the inputs to a Nand Gate are '1', the output would be(a) 1(b) 022. If input 'A' is 1 and input 'B' is 0, then output X will be<image>(a) 0(b) 123. The truth-table of a Nand Gate is

(a)A B X0 0 10 1 11 0 11 1 0(b)A B X0 0 00 1 01 0 01 1 1(c)A B X0 0 00 1 11 0 01 1 1(d) None of these24. IC chip is usually made of(a) Lead(b) Silicon(c) Chromium.(d) None of these.25. Below given network is connected to a 16 V battery with internal resistance of 1 O. What will be current drawn from the battery?<image>(a) 2 A(b) 3 A(c) 12/7 A(d) 7/12 A26.Determine the equivalent resistance of the following network:<image>(a) 6 O(b) 12 O(c) 3 O(d) 9 O.27. A Zener diode is(a) Forward biased heavily doped silicon p-n junction(b) Reversed biased heavily doped silicon p-n junction(c) Forward biased diode operating at breakdown point(d) Is used as rectifying device28. Crystal oscillator is used when frequency required is(a) High(b) Low(c) Constant(d) Varying.29. What is the energy in a quantum of radiation having a wave length of 5000 A?(a) 3.98 x 10-19 J(b) 3.98 x 10-9 J(c) 2.9 x 10-19 J(d) 7.9 x 10-19 J.30. Which of these cannot store energy?

(a) Capacitor(b) Inductor(c) Resistance(d) LC circuit.31. A short bar of magnet placed with its axis at 300 with a uniform external magnetic field of 0.16 T experiences a torque of magnitude 0.032 J. What is the magnetic moment of the magnet?(a) 0.40 JT-1(b) 4.0 JT-1(c) 0.04 JT-1(d) 0.2 JT-132. The total force on a charge 'q' with velocity "V" in an electric field 'E' and magnetic field 'B' will be(a) q (E + V x B)(b) q(E + V.B)(c) qE + VxB(d) q(B + V x E)33. The magnetic field B at the centre of a circular current loop of radius 'a' is given by(a) B =µ0 I/2a(b) B = µ0 I/a(c) B = 2µ0 I/a(d)B = µ0 a/2I34. If f = x2 + 4xy + y2 + 9, then which of the following is not true:(a) ?f/?x = 2x + 4y(b) ?f/?y = 4x + 2y(c) ?2f/?x2 = 2(d) ?2f/?x?y = 435. A hollow metal ball 8 cm in diameter is given a charge of - 4 x 10-8 C. The potential on the surface of the ball is(a) - 9000 V(b) - 900 V(c) - 90 V(d) Zero.36. The effective capacitance between X and Y is<image>(a) 8/3 µF(b) 7/6 µF(c) 5/6 µF(d) 2 µF.37. The amount of work done is joules in carrying a charge + Q alongwith path ABCD and back to A between two oppositely charged plates is:<image>(a) Q(b) 4Q(c)Q/2(d) Zero.38. How many electrons are contained in 1C?(a) 6.25 x 1018(b) 6.25 x 1019(c) 6.25 x 1020(d) 6.25 x 1021

39. The phase angle between voltage and current in an a. c. circuit through a pure capacitance is(a) 180°(b) 90°(c) 60°(d) 0°40. The permeability of a material is 0.998. It is:(a) Diamagnetic(b) Paramagnetic(c) Ferromagnetic(d) Anti ferromagnetic.41. The ratio of the specific charge of an electron to that of a positron is(a) 1:1(b) 1:2(c) 2:1(d) 4:1.42. With increase in temperature, the electrical conductivity of intrinsic semiconductor(a) Increases(b) Decreases(c) First increases then decreases(d) First decreases then increases.43. In a common collector circuit, input resistance is:(a) Very high(b) Very low(c) Zero(d) Moderate.44. A electron jumps from the 4th orbit to the 2nd orbit of hydrogen atom. If R = 107/m, the frequency of emitted radiations will be(a) 3/16 x 105 Hz(b) 3/16 x 1015 Hz(c) 9/16 x 1015 Hz(d) 3/4 x 1015 Hz.45. I amu. equals(a) 1.67 x 10-27 g(b) 1.67 x 10-28 g(c) 1.67 x 10-29 g(d) 1.67 x 10-27 kg46. A tuning fork produces 4 beats/sec both with 50 and 40 cms of a stretched wire of a sonometer. The frequency of the tuning fork is(a) 36 Hz(b) 50 Hz(c) 90Hz(d) 110 Hz47. A particle is executing SHM with an amplitude 4 cm. At what displacement its energy is half kinetic and half potential(a) 2v2cm(b) v2 cm(c) 2 cm(d) 1 cm.

48. An electron moves with a constant velocity V parallel to the direction of uniform magnetic field 'B'. The force experienced by the electron is(a) BeV(b) eV/B(c)B/eV(d) Zero.49.A charged particle is moving along the axis of X. If an electric field is applied along the axis of Y, the motion of the particle in Y-Y plane will be(a) Elliptical(b) Parabolic(c) Circular(d) Linear50. An electric or magnetic field cannot accelerate(a) Electrons(b) Protons(c) Neutrons(d) Alpha particlesBSNL TTA Exam Papers - Computer Related Question Papers1. What is the name of the software that allows us to browse through web pages?(a) Browser(b) Mail Client(c) FTP Client(d) Messenger2. What is the address given to a network called?(a) System Address(b) SYSID(c) Process ID(d) IP Address

3. Which one of the following is a valid DOS command?(a) LIST *.*(b) LIST???.(c) RECOVER A:(d) RENAME A:SAMPLE.TXT C:TEST.DOC4. All system settings in WINDOWS are stored in:(a) CONTROL.INI(b) MAIN.INI(c) SYSTEM.INI(d) SETTING.INI5. Which number system is usually followed in a typical 32-bit computer?(a) 2(b) 10(c) 16(d) 326. Which of the following is not an output device:(a) Printer(b) Scanner

(c) Flat Screen(d) Touch Screen7. A microprocessor is a processor with reduced(a) instruction set(b) power requirement(c) MIPS performance(d) none of the above8. Which of the following is not an output of an assembler?(a) executable program(b) source listing with line numbers and errors(c) a symbol table(d) object program9. Which layer of OSI model is responsible for routing and flow control:(a) Presentation(b) Transport(c) Network(d) Data Link10. Arrays are passed as arguments to a function by(a) value(b) reference(c) both a and b(d) none of the above11. Array is:(a) linear data structure(b) non-linear structure(c) none of the above12. A data structure in which elements are added and removed from only one end, is known as:(a) Array(b) Stack(c) Queue(d) None of the above13. A diamond-shaped box in an Entity-Relationship diagram refers to:(a) Entity(b) Relationship(c) Attribute14. The principle means of identifying entities within an entity set is:(a) Primary Key(b) Record(c) Attribute(d) Tuple15. Modem refers to:(a) Modulator(b) Modulation(c) Demodulator(d) Modulator and Demodulator16. C language is available for which of the following Operating Systems?(a) DOS(b) Windows(c) Unix(d) All of the above17. Which of the following have the fastest access time?

(a) Magnetic Tapes(b) Magnetic Disks(c) Semiconductor Memories(d) Compact Disks18. DMA stands for:(a) Direct Memory Allocation(b) Distinct Memory Allocation(c) Direct Memory Access(d) Distinct Memory Access19. Array subscripts in C always start at:(a):1(b) 0(c) 1(d) Value provided by user20. Which type of commands in DOS needs additional files for their execution?(a) Batch Commands(b) Internal Commands(c) External Commands21. Which of the following statements in regard to Directories is false?(a) Directories can exist inside directories(b) The root directory is always at the highest level(c) Directories with files can be deleted(d) Directories cannot be renamed22. It is better to buffer a table when(a) When a table is read infrequently(b) When a table is linked to check tables(c) When a table is read frequently and the data seldom changes(d) When a single record is to be picked up23. The Operating System is responsible for:(a) Controlling peripheral devices such as monitor, printers, disk drives(b) Provide an interface that allows users to choose programs to run and to manipulate files(c) Manage users’ files on disk(d) All of the above24. A company whishes to connect two sites in different parts of the country together. It is decided to use the telephone system. What device should be connected to the fileservers on each site?(a) Router(b) Modem(c) Switch(d) Hub25. What is a file server?(a) A computer that performs a service for other computers(b) A computer that controls the printers on the network(c) A computer that stores files that are created by network users

26. What is the Protocol used for the Internet?(a) IPX/SPX(b) NetBIOS/NetBEUI(c) CDMA/CA(d) TCP/IP27. Which one of the following is not a Normal Forms (Normalization) rule with regards to the Relational Model?(a) All fields within a table must relate to or directly describe the Primary Key.(b) Repeating Groups must be eliminated from tables.(c) Fields that can contain non-numeric data are to be removed and placed within their own tables with an associated Primary Key.(d) Redundant data is to be eliminated by placing the offending fields in another table.28. Choose the answer which best describes the term Primary Key:(a) The Primary Key is a field that contains data that can be duplicated.(b) The Primary Key is a field that contains data that is unique.(c) The Primary Key is a field that is never associated with any field in other tables.(d) The Primary Key field is a concept used only in Microsoft Access.29. Which technique is used to reduce the size of a file:(a) Compression(b) Decompression(c) Encryption(d) Decryption30. BIOS stands for(a) Binary Input Output Set(b) Binary Input Output System(c) Basic Input Output Set(d) Basic Input Output System

31. A floppy disk is consisting of 40 tracks, each track contains 100 sectors, and the capacity of a sector is 512 bytes, what is the approx. size of that disk?(a) 1 MB(b) 2 MB(c) 4 MB(d) 8 MB32. What is the binary equivalent of a decimal number 68:(a) 1000100(b) 1100100(c) 1000010(d) 100000133. Assembly language to machine language translation is:(a) One-to-One(b) One-to-Many(c) Many-to-One

(d) Many-to-Many34. Maximum size of IP address is:(a) 12 bits(b) 24 bits(c) 32 bits(d) 48 bits35. RAM stands for(a) Read Access Memory(b) Read After Memory(c) Random Access Memory(d) Random After Memory36. What is the final value of sum?main (){int sum=1;for(;sum<=9;)printf(%d\n, ++sum);}(a) 9(b) 10(c) 11(d) none of the above37. If c is a variable initialized to 1, how many times the following loop be executed:while(c>0 && c<60){c++;}(a) 59(b) 6(c) 61(d) none of the above38. The declaration void fun(int) indicates the fun is a function which:(a) has no arguments(b) returns nothing(c) both a and b(d) none of the above39. Out of the following which is not valid network topology:(a) Bus(b) Star(c) Circle(d) Tree40. The overall logical structure of a database can be expressed graphically by:(a) Data Flow Diagram(b) Flow Chart(c) Directed Graph(d) Entity-Relationship Diagram41. CARRY, in a half-adder, can be obtained using:(a) OR gate(b) AND gate(c) EX-OR gate(d) EX-AND gate42. The memory that requires refreshing of data is:(a) SROM(b) DROM

(c) SRAM(d) DRAM43. The minimum number of bits required to represent numbers in the range:28 to +31 is-(a) 5(b) 6(c) 7(d) 844. Which bus carries information between processors and peripherals?(a) Data bus(b) Control bus(c) Address bus(d) Information bus45. Which part of the computer perform arithmetic calculations?(a) Control unit(b) Registers(c) ALU(d) CPU46. A gigabyte represents:(a) 1 billion bytes(b) 1000 kilobytes(c) 230 bytes (d) 10 megabytes47. The minimum number of bits required to store the hexadecimal number FF is:(a) 2(b) 4(c) 8(d) 1648. Cache memory enhances:(a) memory capacity(b) memory access time(c) secondary storage capacity(d) secondary storage access time49. A UPS:(a) increases the storage capacity of a computer system(b) increases the processor speed(c) provides backup power in the event of a power cut\(d) none of the above50. An RDBMS is a:(a) Remote DBMS(b) Relative DBMS(c) Reliable DBMS(d) Relational DBMSBSNL Telecom Technical Assistant (TTA) Recruitment Test: Sample Paper1. One of the following statement which is true for relative dielectric constant is -a) It is dimensionlessb) It is not equal to unity for vacuumc)) It?s value for all substances is less than oned)) None2. Pure metals generally have-

a) high conductivity and low temperature coefficientb) high conductivity and large temperature coefficientc) low conductivity and zero temperature coefficientd) low conductivity and high temperature coefficient3. For small size, high frequency coils, the most common core material isa) Airb) Ferritec) Powdered iond) Steel4. For an abrupt junction Varactor diode, the dependence of device capacitance (C) on applied reverse bias (V) is given by-a) C a V1/3b) C a V-1/3c) C a V1/2d) C a V-1/25. A superconductor is a-a) A material showing perfect conductivity and Meissner effect below a critical temperatureb) A conductor having zero resistancec) A perfect conductor with highest dimagnetic susceptibilityd) A perfect conductor which becomes resistive when the current density through it exceeds a critical value6. When a semiconductor based temperature transducer has a temperature coefficient of ?2500 mV/0C then this transducer is indeed a-a) Thermistorb) Forward biased pn junction diodec) Reverse biased pn junction dioded) FET7. The location of lightning arrestor is -a) Near the transformerb) Near the circuit breakerc) Away from the transformerd) None8. Time constant of an RC circuit increases if the value of the resistance is -a) Increasedb) Decreasedc) Neither a nor bd) Both a and b9. Intrinsic semiconductors are those which -a) Are available locallyb) Are made of the semiconductor material in its purest fromc) Have more electrons than holesd) Have zero energy gaps10. The primary control on drain current in a JFET is exerted by -a) Channel resistance

b) Size of depletion regionsc) Voltage drop across channeld) Gate reverse bias11. The electrical conductivity of metals which is expressed in ohm-1 m-1 is of the order of -a) 1010b) 105c) 10-4d) 10-612. When biased correctly, a zener diode ?a) acts as a fixed resistanceb) has a constant voltage across itc) has a constant current passing through itd) never overheats13. The current amplification factor adc is given by ?a) IC/IEb) IC/IBc) IB/ICd) IB/IC14. Compared to bipolars, FETs have-a) high input impedanceb) low input impedancec) same input impedanced) none15. The source-drain channel of JFET is -a) ohmicb) bilateralc) unilaterald) both a and b16. diac is equivalent to a -a) Pair of SCRsb) Pair of four layer SCRsc) Diode and two resistorsd) Triac width17. When a sample of N type semiconductor has electron density of 6.25 ? 1011 /cm3 at 300K and if the intrinsic concentration of carriers in this sample is 2.5 ? 1013/cm3 then the hole density will be ?a) 106/cm3b) 103/ cm3c) 1010/ cm3d) 1012/ cm318. The statement ‘In any network of linear impedances, the current flowing at any point is equal to the algebraic sum of the currents caused to flow at that point by each of the sources of emf taken separately with all other emf’s reduced to zero? represents -a) Kirchhoff’s lawb) Norton’s theoremc) Thevenin’s theoremd) Superposition theorem19. One of the following modes which has the characteristics of attenuation

becoming less as the frequency is increased and is attractive at icrowave frequencies of circular cylindrical wave guides is ?a) TE1 modeb) TM01 modec) TE01 moded) Higher order mode20. A two-port network is symmetrical if ?a) z11z22 ? z12z21 = 1b) h11h22 ? h12h21 = 1c) AD ? BC = 1d) y11y22 ? y12y21 = 121. For transmission line load matching over a range of frequencies, it is best to use a-a) balunb) broad band directional couplerc) double stubd) single stub of adjustable position22. The poles and zeros of a driving point function of a network are simple and interlace on the negative real axis with a pole closest to the origin. It can be realised -a) by an LC networkb) as an RC driving point impedancec) as an RC driving point admittanced) only by an RLC network23. Poles and zeros of a driving point function of a network are simple and interlace on the jw axis. The network consists of elements ?a) R and Cb) L and Cc) R and Ld) R, L and C24. For a two port reciprocal network, the output open circuit voltage divided by the input current is equal to ?a) Bb) Z12d) h1225. In a short electric doublet the radiation properties are so that-a) The induction field diminishes as the square root of the distance and is only appreciable in the vicinity of the conductor.b) In the radiation, magnetic field is minimum when the current is maximum.c) The radiation resistance of a short doublet antenna is extremely high.d) Mean rate of power through a unit area of spherical sphere surrounding this doublet is proportional to the square of the elemental length, other factors remaining constant.26. The frequency modulated (FM) radio frequency range is nearly -a) 250 ?300 MHz

b) 150 ? 200 MHzc) 90 ? 105 MHzd) 30-70 MHz27. In an underground cable the distortion in the transmission of carrier frequency can be eliminated by using -a) Inductive loadingb) Resistive loadingc) Capacitive loadingd) Shielding28. The charachteristic impendance of a transmission line with inductance 0.294 mH /m and capacitance 60 pF/m is -a) 49 Wb) 60 Wc) 70 Wd) 140 W30. For a quarter wavelength ideal transmission line of characteristic impedance 50 ohms and load impedance 100 ohms, the input impedance will be ?a) 25Wb) 50Wc) 100Wd) 150W31. The depth of penetration or skin depth for an electromagnetic field of frequency ?f? in a conductor of resistivity r and permeability m is-

a) inversely proportional to r and f and directly proportional to mb) directly proportional to r and inversely proportional to f and m

c) directly proportional to f and inversely proportional to r and m

d) inversely proportional to r and m and directly proportional to f

32. When an antenna has a gain of 44dB then assuming that the main beam of the antenna is circular in cross-section the beam width will be -

a) 0.4456 0b) 1.44560c) 2.44560d) 3.44560

33. Lens antennas used for microwaves are usually made of -

a) Polystyreneb) Glass of low refractive indexc) Paraboloid surfacesd) Dielectric media having large refractive index

34. One of the following types of instrument which is an electrometer is -

a) Electrodynamometerb) PMMCc) Electrostaticd) Moving iron

35. When an ac current of 5A and dc current of 5A flow simultaneously through a circuit then which of the following statement is true ?

a) An ac ammeter will read less than 10A but more than 5Ab) An ac ammeter will read only 5Ac) A dc ammeter will read 10Ad) A dc ammeter will read zero36. When Q factor of a circuit is high, then -

a) power factor of the circuit is highb) impedance of the circuit is highc) bandwidth is larged) none of these

37. The resolution of a logic analyser is -

a) the maximum number of input channelsb) the minimum duration of the glitch it can capturec) it’s internal clock periodd) the minimum amplitude of input signal it can display38. A memoryless system is ?

a) causalb) not causalc) nothing can be saidd) none39. An air capacitor is a ?

a) time variantb) active devicec) time invariantd) time invariant and passive device

40. Thermistors are made of -

a) pure metalsb) pure insulatorsc) sintered mixtures of metallic oxidesd) pure semiconductor

41. Pirani gauge is used to measure ?a) very low pressuresb) high pressuresc) pressures in the region of 1 atmd) fluid flow

42. These circuits converts input power at one frequency to output power at a different frequency through one stage conversion ?

a) AC voltage controllersb) Cyclo convertersc) Phase controlled rectifiersd) Inverters

43. In a forward voltage Triggering thyristor changes from ?

a) off state to on stateb) on state to off statec) on state to on stated) off state to off state

44. A thyristor, when triggered, will change from forward blocking state to conduction state if its anode to cathode voltage is equal to -

a) peak repetitive off state forward voltageb) peak working off state forward voltagec) peak working off state reverse voltaged) peak non-repetitive off state forward voltage

45. Gate characteristic of a thyristor-

a) is a straight line passing through originb) is of the type Vg = a + bIgc) is a curve between Vg and Igd) has a spread between two curves of Vg ? Ig

46. A four quadrant operation requires-

a) two full converters in seriesb) two full converters connected back to backc) two full converters connected in paralleld) two semi converters connected back to back47. If for a single phase half bridge inverter, the amplitude of output voltage is Vs and the output power is P, then their corresponding values for a single phase full bridge inverter are ?

a) Vs, Pb) Vs/2, Pc) 2Vs, 2Pd) 2Vs, P

48. In an enhancement type MOSFET the output V-I characteristics has ?

a) only an ohmic regionb) only a saturation region

c) only ohmic region at 10 W voltage value followed by a saturation region at higher voltagesd)an ohmic region at large voltage values preceded by a saturation region at lower voltages

49. The energy gap in a semiconductor -

a) increases with temperatureb) remains constantc) slightly increase with temperatured) decrease with temperature50. In an electronic circuit matching means -

a) connecting a high impedance directly to low impedanceb) selection of components which are compatiblec) transferring maximum amount of signal between different kinds of circuits.d) RC coupled stages

51. P channel FETs are less superior than N channel FETs because

a) They have higher input impedanceb) They have high switching timec) They consume less powerd) Mobility of electrons is greater than that of holes

52. Small increase in temperature in the CE connected transistor is the -

a) Increase in ICEOb) Increase in ac current gainc) Decrease in ac current gaind) Increase in output resistance

53. An amplifier has a band width of 20 KHz and a midband gain of 50 without feedback. If a negative feedback of 1% is applied then bandwidth with feedback is -

a) 13. 3 KHzb) 30KHzc) 10KHzd) 40KHz

54. The output of a class B amplifier -

a) is distortion freeb) consists of positive half cycles onlyc) is like the output of a full wave rectifierd) comprises short duration current pulses

55. An amplifier with negative feedback -

a) lowers its lower 3 dB frequencyb) raises its upper 3 dB frequencyc) increases its bandwidthd) all of the above

56. What changes would be necessary in block C if FM signals are to be received -

a) Block becomes redundantb) A FM detector would be requiredc) A high frequency signal generatord) An additional local oscillator will be needed

57. The main disadvantage of Diode-Transistor logic (DTL) is its-

a) greater speedb) slower speedc) average speedd) none of the above

58. Time delay Dt in digital signals in an SIS O shift register is given by ?

a) Dt = N ? Fcb) Dt = N ? 1/Fcc) Dt = 1/N ? Fcd) Dt = N ? 1/Fc

59. The output Qn is 1 in a JK flip flop and it does not change when clock pulse is applied) The possible combination of Jn and Kn can be ?

(y denotes don’t care)

a) y and 0b) y and 1c) 0 and yd) 1 and y

60. Basic memory cell of dynamic RAM consists of ?

a) a flip flopb) a transistor acting as a capacitorc) a transistord) a capacitance61. The 2′s complement of 10002 is ?

a) 0111b) 0101c) 1000d) 0001

62. Master slave flip-flop is made up of ?

a) two flip flops connected in seriesb) two flip flops connected in parallel

c) a debouncer circuitd) a-D- latch

63. Number of nybbles making one byte is ?

a) 2b) 4c) 8d) 16

64. The intrinsic impedance of free space-

a) is independent of frequencyb) decreases with increase of frequencyc) increases with increase of frequencyd) varies as square root of frequency

65. A system consists of 12 poles and 2 zeroes. Its high frequency asymptote in its magnitude plot has a slope of -

a) ?200 dB/decadeb) ?240 dB/decadec) ?230 dB/decaded) ?320 dB/decade

66. Considering the conditions-

1. High loop gain 2. Less ringing3. Greater damping 4 Negative dB gain margin

System stability requirements would include

a) 1 and 3b) 1, 2 and 3c) 1 and 4d) 2, 3 and 4

67. In the equatorial plane only Geosychronous satellite are launched because it is the only plane which provides ?

a) 24 hour orbitb) stationary satellitec) global communicationd) zero-gravity environs

68. Radio Broadcasting is an example of ?

a) space multiplexingb) time multiplexingc) frequency multiplexingd) none of the above

69. PAM signals can be demodulation by using a ?

a) Low pass filters (LPE) aloneb) A Schmitt trigger followed by a LPFc) A differentiator followed by a LPFd) A clipper circuit by a LPF

70. In an FDM receiver channels can be separated by using ?

a) AND gatesb) Band passc) differentiationd) Integration

71. The most common modulation system used for telegraphy is-

a) frequency shift keyingb) two ? tone modulationc) pulse code modulationd) single tone modulation

72. Use of varoctor diode in generation of modulated segial be-a) FM generation onlyb) 100AM generation onlyc) PM generation onlyd) both PM and AM generation

73. In colour picture tube shadow mask is used to-a) reduce x-ray emissionb) ensure that each beam strikes only its own dotsc) increase screen brightnessd) provide degaussing for the screen

74. The circuit that separates composite video warefore from the sync pulses is-a) the keyed AGC amplifarb) a clipperc) an integratord) a sawtooth current

75. Band width of microwaves is-a) 1GHz -103 GHzb) 1GHz ?100 GHzc) 1 GHz ?10 GHzd) 1 GHz ? 106 GHz

76. In transverse Magnetic mode-a) no electric line is in direction of propagationb) no magnetic line is in direction of propagationc) bath magnetic & electric lines are is direction of propagationd) neither magnetic nor electric lines in direction of propagation

77. Signal transmission in sky wave propagation is due to ?

a) Reforction of wave

b) Reflection of wavec) Pierus through Inosphered) None

78. According to Barkhausen Criterion Phase shift of signal should be ?

a) 600b) 900c) 1800d) 3600

79. The transmission does not have -a) Partition noiseb) Flicker noisec) resistanced) Short noise

80. Varoctor diode has non linearity of -a) capacitanceb) Inductancec) Resistanced) Is a linear device

81. Noise figure is calculated as ?a) i/p signal to noise ratio X o/p signal to noise ratio

b) i/p S/N Ratio / O/P S/N Ratio

c) i/p S/N Ratio / O/P S/N Ratio X 100

d) i/p S/N Ratio + O/P S/N Ratio

82. You can determine quickly the effect of adding poles and zeros by ?

a) Nicholas chartb) Nyquist plotc) Bode plotd) Root locus.

83. The polar plot of G(S) = intercepts real axis at w = wo. Then, the real part and wo are given by-

a) ?5, 1b) ?2.5, 1c) ?5,0-5d) ?5, 2

84. Laplace transform F (s) of a function f (E) is given by

The initial and final values of F (t) will be respectively-

a) zero and 1b) zero and 10c) 10 and zerod) 70 and 80

85. A satellite link uses different frequencies for receiving and transmitting in order to ?

a) avoid interference from terrestrial microwave linksb) avoid interference between its powerful transmitted signals and weak in coming signalc) minimize free-space lossesd) maximize antenna gain

86. The first determining factor in selecting a satellite system is its-

a) EIRPb) Antenna sizec) Coverage aread) Antenna gain

87. Equalizing pulses in TV are sent during-

a) horizontal blankingb) vertical blankingc) the serrationsd) the horizontal retrace

88. The son seems to have ——– from his father a somewhat gloomy and moody manner-

a) washedb) inheritedc) admiredd) attempt

b) Reflection of wavec) Pierus through Inosphered) None

89. Essayist works with words as sculptor with-a) waterb) stonec) aird) hills90. What is a collection of sheep called ?a) bunchb) flockc) herdd) comet91. Join these sentences meaningfully by choosing the correct alternative from the following :You can buy a book. You can read it.a) and

b) norc) eitherd) neither92. What is the opposite of Asperity ?a) gentilityb) superiorityc) kindnessd) clarity93. The Election Commission functions under-a) Ministry of Home Affairsb) Ministry of Lawc) Prime Minister’s Secretariatd) None of these94. Article 352 of Indian Constitution needs to be revoked in case-a) President’s Rule is to be imposedb) Emergency is declaredc) Services of a Government servant are to be terminated without any enquiryd) A political party of national level is to be banned

95. Radio-activity was first discovered by-a) Becquerelb) Madam Curiec) Rutherfordd) Jenner

96. Ninth Plan in India ranges from-a) 1995-2000b) 1996-2001c) 1997-2002d) 1998-2003

97. How much electricity does India propose to generate through nuclear power by the year 2000 AD?a) 5,000 MWb) 10,000 MWc) 15,000 MWd) 20,000 MW

98. In which year did the fall of Bastille take place?a) 1769b) 1789c) 1889d) 1869

99. To form a quorum how many members of the Lok Sabha or Rajya Sabha should be present?a) 1/10th of total membershipb) 1/6th of total membershipc) 1/4th of total membershipd) 1/5th of total membership

100. How may countries are non-permanent members of the Security Council?

a) 6b) 7c) 9d) 10BSNL TTA Question Paper-Electrical Specialization 20071. In a D.C. generator, if the brushes are given a small amount of forward shift, the effect ofarmature isa. Totally demagnetizingb. Totally magnetizingc. Partly demagnetizing and partly cross magnetizingd. Totally cross magnetizing2. The air gap between stator and armature of an electric motor is kept as small as possiblea. To get a stronger magnetic fieldb. to improve the air circulationc. To reach the higher speed of rotationd. To make the rotation easier.3. Two series motors are coupled. One motor runs as generator and other as motor. The frictionlosses of the two machines will be equal whena. Both operates at same voltageb. Both have same back emfc. Both have same speedd. both have same excitation4. Plugging of D.C. motor is normally executed bya. Reversing the field polarityb. Reversing the armature polarityc. Reversing both the armature and field polarityd. Connecting a resistance across the armature.5. Transformer oil transformer providesa. Insulation and coolingb. B. Cooling and lubricationc. Lubrication and insulationd. Insulation, cooling and lubrication6. Leakage fluxes of transformer may be minimized bya. Reducing the magnetizing current to the minimumb. Reducing the reluctance of the iron core to the minimumc. Reducing the number of primary and secondary turn to the minimumd. Sectionalizing and interleaving the primary and secondary windings7. Electric power is transformed upon one coil to other coil in a transformera. Electricallyb. Electro Magneticallyc. Magneticallyd. Physically

8. The most suitable and economical connection for small high voltage transformer isa.Star- Delta connectionb. Delta- Delta connectionc. Delta- Star connectiond. Star- Star connection9. An alternator is said to be over excited when it is operating ata. Unity power factorb. Leading power factorc. Lagging power factord. Either lagging or leading power factor10. In an A.C. machine, the armature winding is kept stationary while the field winding is keptrotating for the following rasona. Armature handles very large currents and high voltagesb. Armature friction involving deep slots to accommodate large coils is easy if armature is keptstationaryc. Ease of cooling the stator than rotord. None of the above.11. In a synchronous motor, the torque angle is thea. Angle between the rotating stator flux and rotor polesb. Angle between the magnetizing current and back emfc. Angle between the supply voltage and back emfd. None of the above12. A 3-phase synchronous motor is said to be "floating" when it operatesa. On no load and without lossb. On constantly varying loadc. On pulsating loadd. On high load and variable supply voltage13. Speed of synchronous motor depends upona. Number of polesb. Supply frequencyc. Both (a) and (b)d. Neither (a) nor (b)14. Imbalance in the shaft of an induction motor occurs due toa. Slip ringsb. Overheating of windingc. Non uniform of air gapd. Rigid consturcion15. Squirrel cage induction motor hasa. Zero starting torqueb. Very small starting torquec. Medium starting torqued. Very high starting torque16. The principle of operation of a 3-phase induction motor is similar to that of aa. Synchronous motor

b. Repulsion - start induction motorc. Transformer with a shorted secondaryd. Capacitor - start, induction - run motor17. The speed/load characteristics of a universal motor are similar to thosea. D.C. shunt motorb. D.C. series motorc. A.C. motord. None of the above18. Single phase A.C. motor generally used for vacuum cleaners isa. Universal motorb. Repulsion motorc. Hysteresis motord. Reluctance motor19. Buchholz relay is used for the protection ofa. Switch yardb. Transformersc. Alternatorsd. Transmission lines20. The type of braking used in traction system isa. Mechanical brakingb. Electro - pneumatic brakingc. Vacuum braking systemd. All the above21. The function of processing zenger diode in a UJT circuit used for triggering of SCRs is toa. Expedite the generation of triggering pulsesb. Delay the generation of triggering pulsesc. Provide a constant voltage to UJT to prevent erratic firingd. Provide a variable voltage to UJT as the source voltage changes22. The frequency of a ripple in the output voltage of a 3 - phase semi converter depends upona. Firing angle and load resistanceb. Firing angle and supply frequencyc. Firing angle and load inductanced. Only on load circuit parameters23. The SCR is turned off when the anode currents falls belowa. Forward current ratingb. Break - over voltagec. Holding currentd. Latching24. V4 characteristics of emitter of a UJT isa. Similar to CE with linear and saturation regionb. Similar to FET with a linear and pinch of regionc. Similar to tunnel diode in some respectsd. Linear between the peak point and valley point

25. A transformer works ona. DCb. ACc. AC & DC bothd. Neither AC not DC26. Which of the following device is used in transformer?a. Tube lightb. Electric heaterc. Mobile phoned. Rectifier module27. Earth electrodes can be in the form ofa. rods or piperb. stripesc. platesd. any of above28. Carbone or metal brushes are used ina. DC generators onlyb. AC generators onlyc. Both AC & DC generationd. None of above29. Energy is lost due to Joule's heating effects in winding of transformer. This is calleda. Copper lossb. Eddy current lossc. Flux lossd. None30. In refrigeration cycle heat is lost ina. Cooling coilb. Condenserc. Compressord. Expansion valve31. The power factor of AC circuit isa. R/Xb. R/Zc. Z/Rd. Zero32. Silicon controlled output is good if ripple factor isa. Switchb. Transformerc. Amplifierd. None of above33. The rectifier output is good if ripple factor is\a. Moreb. Lessc. Constantd. None of above34. Protective relays can monitor large AC current by means ofa. Current transformerb. Potential transformerc. Micro transformerd. None of above35. The combines AM of two similar batteries connected in parallel is:a. halvedb. doubled

c. remain constantd. none of above36. The current in circuit having 5 V EMI source and 10 Ohm resistance is:a. 2 Ampb. 50 Ampc. 5 Ampd. ½ Amp37. The chopper is a device to changea. Voltageb. Currentc. Frequencyd. None of these38. The power consumption, in case of centrifugal loads (like pump, fan, blower etc) isproportional to:a. speedb. square of speedc. cube of speedd. none of these39. Which of these need to be measured after rewinding the motor:a. no load currentb. air gapc. winding resistanced. all of the above40. Five percent increase in supply frequency will change the synchronous speed of motor by:a. -5%b. +5%c. -10%d. +10%41. Which of the following is the best inverter?a. square wave inverterb. sine wave inverterc. pure sine wave inverterd. triangular wave inverter42. For driving a motor in a tape recorder or record player, the motor used is generally:a. a synchronous motorb. a hydraulic motorc. an induction motord. a dc series motor43. The DC motor starter used with a constant speed shunt motor is:a. 2 point starterb. 3 point starterc. 4 point starterd. 5 point starter44. A commutator in a DC motor convertsa. AC to DCb. DC to ACc. Both AC to DC and DC to ACd. None of these45. Two transformers running in parallel will share the load according to their:a. leakage reactance

b. pu impedancec. efficiencyd. rating46. The size of the Earth Wire is determined by:a. the ampere capacity of the service wiresb. the atmospheric conditionsc. the voltage of service wiresd. none of these47. The function of lightning arrester is:a. to limit the short circuit fault currentb. to provide path to high voltage surge to earthc. to reduce arcingd. none of these48. Surge protector provide:a. high impedance to normal voltageb. low impedance to surgec. both (a) and (b)d. none of these49. Earthing is necessary to give protection againsta. voltage fluctuationb. overloadingc. danger of electric shockd. high temperature of conductors50. The primary function of fuse is toa. protect the applianceb. open the circuitc. prevent excessive currentd. protect the lineBSNL TTA Question Paper-Communication Specialization 2007(1) The most common modulation system used for telegraphy is(a) FSK(b) PSK.(c) PCM(d) single tone modulation(e) Two tone modulation(2)VSB is an abbreviation of vestigal sideband, is derived by filtering(a) DSB(b) AM(c) either (a) or (b)(d) PM(3) The Hartely law states that(a) The maximum rate of information transmission depends on the depth of modulation(b) The maximum rate of information depends on the channel bandwidth.(c) Only binary codes may be used(d) Redundancy is essential(4) The FM signal with, a modulation index mf is passed through a frequency tripler. The wave inthe output of the tripler will have a modulation index of(a) mf/9

(b) mf/3(c) mf(d) 3 mf(e) 9mf(5) In high power AM transmission, modulation is done at(a) Buffer stage(b) Oscillator stage(c) RF power stage(d) If stage(6) Companding is used(a) In delta modulator to combat noise(b) To limit amplitude in PCM transmitters.(c) In PWM for working it with TDM(d) To protect small signals in PCM from quantizing distortion(e) In PCM to reduce the SNR(7) In PCM system the SNR of the output signal increases(a) Inversely with bandwidth(b) Exponential with bandwidth(c) With rate of sampling(d) At low frequencies only(8) Armstrong modulator generates(a) Phase modulated signal(b) Frequency modulated signal(c) Both of these(d) Pulse code modulated signal(e) AM and PCM signals(9) A Klystron is a cavity acting as buncher and catcher is used as microwave tube for(a) Guiding waves(b) Velocity modulation(c) frequency modulation(d) impedance matching(e) All of these(10) Easily adjustable tuning component in a waveguide is(a) plunger(b) plunger and stub(c) screw(d) both (a) and (c)(e) both (b) and (c)(11) A ferrite is(a) A non-conductor with magnetic properties(b) A conductor with magnetic properties(c) A semiconductors(d) An insulator which attenuates magnetic fields(e) A compound with good conductivity.(12) Vacuum tubes eventually fail at microwave frequencies because of their(a) Inter electrode capacitance(b) Small series inductance(c) Large shunt capacitance(d) Short transit time(e) Increased noise figure

(13) The biggest disadvantage the IMP ATT diode has is its(a) Low Efficiency(b) high noise(c) Low BW(d) inability to provide pulse operation(e) low power handling ability(14) In AM transmission the frequency, which is not transmitted is(a) carrier frequency(b) audio frequency(c) upper side frequency(d) lower side frequency(15) FM broadcast band lies in(a) VHF(b) UHF(c) SHF(d) HF(16) Automatic gain control is used(a) to maintain the tuning correct(b) to reduce the voltage of loud passage of music(c) to maintain the same amount of output, when stations of different strength are received(d) to increase the amplification at high frequencies(17) The modulation system inherently is most noise resistant in(a) SSB suppressed carrier(b) FM(c) PPM(d) PCM(18) In practical waveguide act as(a) low pass filter(b) high pass filter(c)band pass filter(d)band stop filter(19) The antenna efficiencies achieved in practice depend upon(a) wave length(b) impedance(c) frequency(d) none of above(20) The process of compressing the digital codes at the transmitter and then expanding themback to their original form at receiver is known as(a) Quantizing(b) companding(c) step sizing(d) modulation(21) Digital transmission efficiency is given by(a) information bits/total bits(b) total bits/information bits(c) redundant bits/information bits(d) none of the above(22) The speed of BRI ISDN interface is(a) 2B + D(b) 2D + B

(c) 30B + D(d) 30D + B(23) Which of the following is not a microwave generation source?(a) Klystron(b) Magnetron(c) TWT(d) Diode(24) A signal of maximum frequency of 1 KHz is sampled at Nyquist Rate. The interval betweentwo successive samples is:(a) 50 micro seconds(b) 100 micro seconds(c) 500 micro seconds(d) 1000 micro seconds(25) In order to get back the original signal, it is necessary to use:(a) low pass filter(b) high pass filter(c) band pass filter(d) band reject filter(26) Man made noise id caused by:(a) Solar eruptions(b) Distant Stars(c) Lightning Discharges(d) Arc discharge in electric machines(27) At microwave frequencies, the size of antenna becomes(a) very large(b) large(c) small(d) very small(28) Due to curvature of earth, microwave repeaters are placed at distance of about(a) l0 Km(b) 50 Km(c) 200 Km(d) 500 Km(29) For handling large microwave power, the best medium is(a) coaxial line(b) rectangular waveguide(c) stripline(d) circular wave guide(30) An attenuator is used with TWT to(a) prevent oscillations(b) increase gain(c) prevent saturation(d) help bunching(3l) TWT is basically(a) an oscillator(b) tuned amplifier(c) wideband amplifier(d) an audio amplifier(32) The negative resistance in Gunn diode is due to(a) electron transfer to a less mobile energy level(b) high reverse bias

(c) electron domain formation at the junction(d) tunneling across the junction(33) Which of the following sinusoidal oscillator is preferred for microwave frequencies?(a) resonant circuit oscillator(b) RC phase shift oscillators(c) negative resistance oscillators(d) all of the above(34) When electromagnetic waves are propagated in a waveguide(a) they travel along the walls of the waveguide(b) they travel through the dielectric without touching the walls(c) they are reflected from the walls but do not travel along the walls(d) none of above(35) Wave guides are generally made of(a) Cast iron or steel(b) White metal or gun metal(c) bronze or aluminium(d) plastic or bakelite(36) The cut off frequency of a wave guide means(a) lower frequencies will not be propagated(b) it determines the dimensions of the wave guide(c) frequency at which zero transmission takes place(d) None of above(37) In case of matched load(a) Transmission is zero(b) reflection is zero(c) reflection is unity(d) transmission is equivalent to reflection(38) In an AM wave with 100% modulation, the carrier is suppressed. The percentage of powersaving will be(a) 100%(b) 50%(c) 25%(d) 66.7%(39) The function of AM detector circuit is(a) to rectify the input signal(b) to discard the carrier(c) to provide the audio signal(d) All of the above(40) In FM, the noise can be further decreased by(a) decreasing deviation(b) increasuig deviation(c) keeping deviation constant(d) none of these(41) In PPM, message resides in(a) Pulses(b) time location of pulse edges

(c) none of these(42) Which of the following pulse systems is preferred for communication in presence of noise?(a) PAM(b) PDM(c) PPM(d) none of above(43) Which of the following pulse systems requires higher bandwidth(a) PAM(b)PDM(c)PPM(d)none of these(44) The audio frequency range lies between(a) 20 to 20,000 Hz(b) 20 to 20,000 KHz(c) 400 to 8,000Hz(d) 500 to 5,000 Hz(45) Maximum undistorted power output of a transmitter is obtained when its modulation is:(a) more than 100%(b) 100%(c) less than 100%(d) 50%(46) The AGC voltage in a radio receiver is proportional to(a) the amount of modulation(b) the amplitude of audio signal(c) the amplitude of IF carrier(d) none of these(47) An FM transmitter has maximum frequency deviation of 75 KHz and reproduces audiosignal up to 15 KHz. Minimum channel width required, in KHz is(a) 180(b) 120(c) 90(d) 60(48) With 100% modulation, ratio of side band power to total power transmitted in an amplitudemodulated wave is(a) 2/3(b) l/3(c) l/2(d) l/4(49) To increase the Q factor of an induction, it wound with(a) thicker wire(b) thinner wire(c) longer wire(d) wire with heavy insulation(50) Power factor of a purely resistive circuit is:(a) zero(b) one(c) 0.5(d) infinity

BSNL TTA Question Paper-Instruments and MeasurementSpecialization 2007(1) Instrument is a device for determining(a) the magnitude of a quantity(b) the physics of a variable(c) either of the above(d) both (a) and (b)(2) Electronic instruments are preferred because they have(a) no indicating part(b) low resistance in parallel circuit(c) very fast response(d) high resistance in series circuit(e) no passive elements.(3) A DC wattmeter essentially consist of(a) two ammeters(b) two voltmeters(c) a voltmeter and an ammeter(d) a current and potential transformer(4) Decibel is a unit of(a) power(b) impedance(c) frequency(d) power ratio(5) A dc voltmeter may be used directly to measure(a) frequency(b) polarity(c) power factor(d)power(6) An accurate voltmeter must have an internal impedance of(a) very low value(b) low value(c) medium value(d) very high value(7) The insulation resistance of a transformer winding can be easily measured with(a) Wheatstone bridge(b) megger(c) Kelvin bridge(d) voltmeter(8) A 100 V voltmeter has full-scale accuracy of 5%. At its reading of 50 V it will give an error of(a) 10%(b) 5%(c) 2.5%(d) 1.25%(9) You are required to check the p. f. of an electric load. No p.f. meter is available. You woulduse:(a) a wattmeter(b) a ammeter, a voltmeter and a wattmeter(c) a voltmeter and a ammeter(d) a kWh meter

(10) The resistance of a field coil may be correctly measured by using(a) a voltmeter and an ammeter(b) Schering bridge(c) a Kelvin double bridge(d) a Maxwell bridge(11) An analog instrument has output(a) Pulsating in nature(b) Sinusoidal in nature(c) Which is continuous function of time and bears a constant relation to its input(d) Independent of the input quantity(12) Basic charge measuring instrument is(a) Duddel's oscillograph(b) Cathode ray oscillograph(c) Vibration Galvanometer(d) Bailastic Galvanometer(e) Battery Charging equipment(13) A.C. voltage can be measured (using a d.c. instrument) as a value obtained(a) by subtracting the d.c. reading from it's a.c. reading.(b) Using the output function of the multimeter(c) By using a suitable inductor in series with it(d) By using a parallel capacitor with it(e) None of the above(14) A moving coil permanent magnet ammeter can be used to measure(a) D. C. current only(b) A. C. current only(c) A. C. and D. C. currents(d) voltage by incorporating a shunt resistance(e) none of these(15) Select the wrong statement(a) the internal resistance of the voltmeter must be high(b) the internal resistance of ammeter must be low(c) the poor overload capacity is the main disadvantage of hot wires instrument(d) the check continuity with multimeter, the highest range should be used.(e) In moving iron voltmeter, frequency compensation is achieved by connecting a capacitor across itsfixed coil.(16) Which of the following instrument is suitable for measuring both a.c. and d.c.quantities.(a) permanent magnet moving coil ammeter.(b) Induction type ammeter.(c) Quadrant electrometer.(d) Moving iron repulsion type ammeter.(e) Moving iron attraction type voltmeter.

(17) Swamping resistance is used in moving coil instruments to reduce error due to(a) thermal EMF(b) temperature(c) power taken by the instrument(d) galvanometer sensitivity.(18) A power factor meter is based on the principle of(a) electrostatic instrument(b) Electrodynamometer instrument(c) Electro thermo type instrument(d) Rectifier type instrument.(19) A potentiometer recorder is used for(a) AC singles(b) DC signals(c) both (a) and (b)(d) time varying signals(e) none of these.(20) Transformers used in conjunction with measuring instruments for measuring purposes arecalled(a) Measuring transformers(b) transformer meters(c) power transformers(d) instrument transformers(e) pulse transformers.(21) Leakage flux in an electrical machine is measure by(a) Ballistic galvanometer(b) Flux meter(c) Either (a) or (b)(d) Vibration galvanometer(e) CRO(22) A C.R.O. is used to indicate(a) supply waveform(b) magnitude of the applied voltage(c) B.H. loop(d) all of these(e) Magnitude of the current flowing in it.(23) An oscillator is a(a) an amplifier having feedback network(b) a high gain amplifier(c) a wide band amplifier(d) a untuned amplifier(e) None of these(24) Distortion can be measured by(a) Wave meter(b) Digital filters(c) Wein bridge circuit(d) Bridge T filter circuit(25) Series connected Q- meter is preferable for measurement of components having(a) high impedance(b) low impedance(c) both (a) and (b)(d) high frequency(e) low capacitance(26) A potentiometer is(a) an active transducer

(b) a passive transducer(c) a secondary transducer(d) a digital transducer(e) a current sensing transducer(27) The basic components of a digital voltmeter are:(a) A/D converter and a counter(b) A/D converted and a rectifier(c) D/A converter and a counter(d) Ramp generator and counter(e) Comparator(28) Which of the following electrical equipment cannot convert ac into dc(a) diode(b) converter(c) transformer(d) mercury arc rectifier(29) Voltage measurement are often taken by using either a voltmeter or(a) an ammeter(b) an ohmmeter(c) an oscillator(d) a watt-meter(30)The electric device which blocks DC but allows AC is called:(a) capacitance(b) inductor(c) an oscilloscope(d) a watt-meter(31 ) The range of an ammeter can be extended by using a(a) shunt in series(b) shunt in parallel(c) multiplier in series(d) multiplier in parallel(32)A device that changes one form of energy to another is called(a) rheostat(b) oscillator(c) transducer(d) varicap(33) Aquadag is used in CRO to collect(a) primary electron(b) secondary electron(c) both primary and secondary(d) none of above(34) A vertical amplifier for CRO can be designed for(a) only a high gain(b) only a broad bandwidth(c) a constant gain time bandwidth product(d)all of the above(35) One of the following is active transducer(a) Strain gauge(b) Selsyn(c) Photovoltic cell(d) Photo emissive cell(36) The dynamic characteristics of capacitive transducer are similar to those of

(a) low pass filter(b) high pass filter(c) band pass filter(d) band stop filter(37) Thermocouples are(a) passive transducers(b) active transducers(c) both active and passive transducers(d) output transducers(38) The size of air cored transducers as compare to iron core counter part are(a) bigger(b) smaller(c) same(39) From the point of view of safety, the resistance of earthing electrode should be:(a) low(b) high(c) medium(d) the value of resistance of electrode does not effect the safety(40) In CRT the focusing anode is located(a) between pre accelerating and accelerating anodes(b) after accelerating anodes(c) before pre accelerating anodes(d) none of above(41) Which transducer converts heat energy into electrical energy(a) I. V. D. T.(b) thermocouple(c) photoconductor(d) none of the above(42) Which of photoelectric transducer is used for production of electric energy by convertingsolar energy(a) photo emission cell(b) photo diode(c) photo transistor(d) both (b) and (c)(43) Which of the following instruments consumes maximum power during measurement?(a) induction instruments(b) hot wire instruments(c) thermocouple instruments(d) electrodynamometer instruments(44) Which of the following meters has the best accurancy(a) moving iron meter(b) moving coil meter(c) rectifier type meter(d) thermocouple meter(45) The function of the safety resistor in ohm meter is to(a) limit the current in the coil(b) increase the voltage drop across the coil(c) increase the current in the coil

(d) protect the battery(46) Which of the following instruments is free from hysteresis and eddy current losses?(a) M.l. instrument(b) electrostatic instrument(c) electrodynamometer type instrument(d)all of these(47) The dielectric loss of a capacitance can be measured by(a) Wien bridge(b) Owen bridge(c) Schering bridge(d) Maxwell bridge(48) Reed frequency meter is essentially a(a) recording system(b) deflection measuring system(c) vibration measuring system(d) oscillatory measuring system(49) In measurements made using a Q meter, high impedance elements should preferably beconnected in(a) star(b) delta(c) series(d) parallel(50) A digital voltmeter measures(a) peak value(b) peak-to-peak value(c) rms value(d) average valueBSNL TTA Question Paper Control Systems Specialization 20071. An open loop control system has its(a) control action independent of the output or desired quantity(b) controlling action, depending upon human judgment(c) internal system changes automatically taken care of(d) both (a) and (b)(e) all (a),(b) and (c)2. A servo system must have(a) feedback system(b) power amplifier to amplify error(c) capacity to control position or its derivative(d) all of these(e) none of these3. The major disadvantage of a feedback system may be

(a) Inaccuracy(b) inefficiency(c) Unreliability(d) instability(e) Insensitivity4. Properties of a transfer function

(a) It is ratio of two polynomials is S and assumes zero initial conditions(b) It depends on system elements and not input and output of the system(c) Coefficients of the powers of S in denominator and numerator are all real constant. The order ofdenominator is usually greater than or equal to the order of numerator(d) All of these(e) It is a function which transfer one physical system into another physical system.5. The classical analogous of a simple lever is(a) Capacitor bridge(b) transformer(c) mutual inductor(d) either of these6. Two blocks G1(s) and G2(s) can be cascaded to get resultant transfer function as(a) G1(s) + G2(s)(b) G1(s) / G2(s)(c) G1(s) G2(s)(d) 1+G1(s) G2(s)(e) 1-G1(s)G2(s)(f) two blocks cannot be cascaded7. The principles of homogeneity and super position can be applied to(a) linear time invariant system(b) non-linear time invariant system(c) digital control system(d) both (a) and (b)8. Pick up the nonlinear system(a) automatic voltage regulator(b) d.c. servomotor with high field excitation(c) temperature control of a furnaces using thermistor(d) speed control using SCR(e) all of these9. Signal flow graph (SFG) is a(a) polar graph(b) semi log graph(c) log log graph(d) a special type of graph for analyzing modem control system(e) a topological representation of a set of differential equations10. Disadvantages of magnetic amplifier(a) time lag, less flexible, non-sinusoidal waveform(b) low power consumption and isolation of the active circuit(c) saturation of the core(d) all of these11. Pick up false statement regarding magnetic amplifiers(a) The gate coil of an ideal magnetic amplifier has either zero or infinite inductance

(b) Resistance of control and gate winding is very small(c) Magnetic amplifier gas dropping load characteristics(d) Magnetic amplifiers are not used to control the speed of d.c. shunt motor(e) Magnetic amplifiers can be used in automatic control of electric drivers of higher rating.12. High power amplification is achieved by using(a) push pull amplifier(b) amplidyne(c) magnetic amplifier(d) DC amplifier(e) D.C. generator13. Pick up false statement regarding servomotors(a) The d.c. servomotors are lighter than equivalent a.c. servomotors(b) The d.c. servomotors develops higher starting and reversing torque than equivalent a.c. servomotor.(c) A drag cup a.c. servomotor has one windings on stator and other on rotor(d) Output power of servomotors varies from 1/20 W to 100 W14. To reduce steady state error(a) decrease natural frequency(b) decrease damping(c) increase damped frequency(d) increase time constant(f) increase gain constant of the system15. A good factor for Mp should be(a) less than 1(b) lying between 1.1 and 1.5(c) more than 2.2(d) zero(e) infinity16. Pick up false statement. Routh-Hurwitz criterion(a) is used for determining stability of a system(b) is an algebraic procedure(c) gives the exact location of roots of the characteristic equation(d) does not indicate relative degree of stability or instability17. Which of the following is the time domain method of determining stability of a control system(a) Bode plot(b) Nyquist plot(c) Nicholos chart(d) Routh-Hurwitz array(e) Constant M and (fy) locus(f) Root locus technique18. The technique which gives transient response quickly as well as stability information is(a) Nyquist plot(b) Routh-Hurwitz criteria

(c) Bode plot(d) Root locus plot(e) Nichols plot19. The bandwidth can be increased by use of(a) phase lag network(b) phase lead network(c) both (a) and (b) in cascade(d) both (a) and (b) in parallel(e) none of these20. Nyquist plot is drawn on(a) semi log graph paper(b) log log graph paper(c) polar graph paper(d) centimeter graph paper21. If the gain margin is positive and the phase margin is negative the system is(a) stable(b) unstable(c) indeterminist22. The Bode plot is applicable to(a) all phase network(b) minimum phase network(c) maximum phase network(d) lag lead network(e) none of these23. The valid relation between setting time ts and rise time tr is(a) tr>ts(b) ts>tr(c) ts=tr(d) none of these24. As a root moves further away from imaginary axis the stability(a) increases(b) decreases(c) not affected(d) none of these25. Flat frequency response means that the magnitude ratio of output to input over thebandwidth is(a) variable(b) zero(c) constant(d) none of above26. How many octaves are between 200 Hz and 800 Hz(a) Two octave(b) One octave(c) Four octave(d) None of above27. Human system can be considered as(a) open loop system(b) close loop system with single feedback(c) close loop system with multivariable feedback(d) none of these28. In a feedback system the transient response(a) Decays at constant rate

(b) gets magnified(c) decays slowly(d) decays more quickly29. Transfer function of a system is used to calculate(a) the steady state gain(b) the main constant(c) the order of system(d) the output for any given input(e) all of the above30. Transfer function of a system is defined as the ratio of output to input in(a) Laplace transform(b) Z-transform(c) Fourier transform(d) Simple algebraic form31. Introduction of feedback decreases the effect of(a) disturbances(b) noise signals(c) error signals(d) all the above32. The system response of a system can be best tested with(a) unit impulse input signal(b) ramp input signal(c) sinusoidal input signal(d) exponentially decaying input signal33. Which of the following is a closed loop system(a) electric switch(b) car starter(c) de generator(d) auto-pilot for an aircraft34. Which of the following is used as an error detector(a) potentiometer(b) field controlled ac motor(c) amplidyne(d) armature controlled ac motor35. The break away point of root loci are(a) open loop poles(b) closed loop poles(c) open loop zeros(d) closed loop zeros36. Noise in a control system can be kept low by(a) reducing the bandwidth(b) attenuating such frequencies at which external signals get coupled into the system(c) both (a) and (b)(d) none of these37. Main cause of absolute instability in the control system is(a) parameters of controlling system(b) parameters of controlled system(c) parameters of feedback system(d) error detector where the two signals are compared38. Basically a controller is(a) a amplifier

(b) a clipper(c) a comparator(d) a summer39. A system with gain margin close to unity or a phase margin close to zero is(a) highly stable(b) highly oscillatory(c) relatively stable(d) none of these40. Which of following elements is not used in an automatic control system(a) sensor(b) error detector(c) oscillator(d) final control element41. AC systems are usually preferred to the DC systems in control applications because(a) AC systems are cheaper(b) AC systems are more stable(c) AC systems have better performance characteristics and smaller in size(d) all of these42. A system has the transfer function (1-s)/(1+s); It is known as(a) low pass system(b) high pass system(c) all pass system(d) none of the above43. In control systems, excessive bandwidth should be avoided because(a) noise is proportional to bandwidth(b) it leads to low relative stability(c) it leads to slow speed of response(d) none of these44. In most systems, an increase in gain leads to(a) larger damping ratio(b) smaller damping ratio(c) constant damping ratio(d) none of these45. A step function is applied to the input of a system and output is of the form y = t, the system is(a) stable(b) unstable(c) not necessarily stable(d) conditionally stable46. Which of the following can be magnified by magnetic amplifier(a) voltage(b) current(c) power(d) none of above47. The inductance is not used in lag network because of(a) big size(b) time delay and hysteresis losses(c) high reactance(d) none of these48. Saturation in a stable control system can cause

(a) conditional stability(b) over damping(c) low level oscillations(d) high level oscillations49. Excessive noise in control systems can cause(a) reduction in bandwidth(b) reduction in gain(c) saturation in amplifying stages(d) oscillations50. The type-0 system has(a) net pole at the origin(b) no pole at the origin(c) simple at one origin(d) two poles at the origin