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BSNL JTO Exam - 2005

1. If the voltage applied across a capacitance is
   triangular in waveform then the waveform of the current is-Answer is :- Rectangular
2. One of the following statement which is true for
   relative dielectric constant is -Answer is :- It is dimensionless
3. Pure metals generally have-Answer is :- high
   conductivity and large temperature coefficient
4. For small size, high frequency coils, the most common
   core material isAnswer is :- Air

5. For an abrupt junction Varactor diode, the dependence of device capacitance (C) on applied reverse
   bias (V) is given by-

   Answer is :- C
   a V^-1/3

6. A superconductor is a-

   Answer is :-A material showing perfect conductivity and Meissner effect below a critical temperature

7. When a semiconductor based temperature transducer has a temperature coefficient of –2500 mV/⁰C
   then this transducer is indeed a-

   Answer is :- Forward biased pn junction diode

8. The location of lightning arrestor is -

   Answer is :- Near the transformer

9. Time constant of an RC circuit increases if the value of the resistance is -
   Answer is :- Increased

10. Intrinsic semiconductors are those which -
    Answer is :- Are made of the semiconductor material in its purest from

11. The primary control on drain current in a JFET is exerted by -
    Answer is :- Gate reverse bias

12. The electrical conductivity of metals which is expressed in ohm^-1 m^-1
    is of the order of -
    Answer is :- 10⁵

13. When biased correctly, a zener diode –
    Answer is :- has a constant voltage across it

14. The current amplification factor a_dc is given by
    –
    Answer is :- I_C/I_E

15. Compared to bipolars, FETs have-
    Answer is :- high input impedance

16. The source-drain channel of JFET is -
    Answer is :- both a and b

17. A diac is equivalent to a -
    Answer is :- Pair of four layer SCRs

18. 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–
    Answer is :- 10³/ cm³

19. When the two networks shown in fig. are equivalent
    with respect to the terminals 1 and 2 at all frequencies then the values of
    C_A, L_B, L_C and C_C will be
    Answer is :- 0.5, 3, 6, 0.166
20. The transmission parameter of the network C when the
    transmission parameter of the network A and B are and respectively are - Answer is :-
21. 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 -
    Answer is :- Superposition theorem
22. 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
    –
    Answer is :- TE₀₁mode
23. A two-port network is symmetrical if –Answer is :-AD – BC = 1
24. For transmission line load matching over a range of
    frequencies, it is best to use a-
    Answer is :- double stub
25. 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 -
    Answer is :- only by an RLC network
26. Poles and zeros of a driving point function of a network are simple and interlace on the jw axis. The network consists of elements –
    Answer is :- L and C
27. For a two port reciprocal network, the output open circuit voltage divided by the input current is equal to –
    Answer is :- Z₁₂
28. In a short electric doublet the radiation properties
    are so that-
    Answer is :-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.
29. The frequency modulated (FM) radio frequency range is
    nearly -Answer is :-90 – 105 MHz
30. In an underground cable the distortion in the
    transmission of carrier frequency can be eliminated by using -
    Answer is :- Inductive loading
31. The characteristic impendence of a transmission line
    with inductance 0.294 mH
    /m and capacitance 60 pF/m is -
    Answer is :- 70 W
32. One of the following statements which is not true for
    a strip line compared to a waveguide is –
    Answer is :- It has a smaller bandwidth
33. For a quarter wavelength ideal transmission line of
    characteristic impedance 50 ohms and load impedance 100 ohms, the input
    impedance will be –
    Answer is :- 25W
34. The depth of penetration or skin depth for an
    electromagnetic field of frequency ‘f’ in a conductor of resistivity r
    and permeability m is-
    Answer is :- directly proportional to r
    and inversely proportional to f and m
35. 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 -
    Answer is :- 2.4456⁰
    
36. Lens antennas used for
    microwaves are usually made of -Answer is :- Polystyrene
37. One of the following types of instrument which is an
    electrometer is -
    Answer is :- Electrostatic
38. When an ac current of 5A and dc current of 5A flow
    simultaneously through a circuit then which of the following statement is true
    ?Answer is :- An ac ammeter will read less than 10A but more than 5A
39. When Q factor of a circuit is high, then -
    Answer is :- none of these
40. The resolution of a logic analyser is -
    Answer is :- the minimum amplitude of input signal it can display
41. The aperture time of an A to D converter is given by
    Answer is :-
42. A memory less system is –
    Answer is :- causal
43. An air capacitor is a –
    Answer is :-time invariant and passive device
44. Thermistors are made of -
    Answer is :- sintered mixtures of metallic oxides
45. Pirani gauge is used to measure –Answer is :- very low pressures
46. These circuits converts input power at one frequency
    to output power at a different frequency through one stage conversion –
    Answer is
    :-Cyclo converters
47. In a forward voltage Triggering thyristor changes
    from –Answer is :- off state to on state
48. Q factor of a coil in Maxwell bridge is obtained as
    –
    Answer is :-
49. A thyristor, when triggered, will change from forward
    blocking state to conduction state if its anode to cathode voltage is equal to
    -
    Answer is :- peak working off state forward voltage
50. Gate characteristic of a
    thyristor-
    Answer is :-has a spread between two curves of V_g – I_g
51. A four quadrant operation requires-
    Answer is :-two full converters connected back to back
52. . If for a single phase half bridge inverter, the
    amplitude of output voltage is V_s and the output power is P, then
    their corresponding values for a single phase full bridge inverter are –
    Answer is :- 2V_s, 2P
53. For critical damping of the resonant circuit
    consisting of R_d, L, C in series is –
    Answer is :-
54. In an enhancement type MOSFET the output V-I
    characteristics has –
    Answer is :- only ohmic region at 10 W voltage value followed by a
    saturation region at higher voltages
55. The energy gap in a
    semiconductor -
    Answer is :-decrease with temperature
56. In an electronic circuit
    matching means -
    Answer is :-transferring maximum amount of signal between
    different kinds of circuits.
57. P channel FETs are less
    superior than N channel FETs because
    Answer is :- Mobility of electrons is
    greater than that of holes
58. Small increase in temperature
    in the CE connected transistor is the -
    Answer is :- Increase in I_CEO
59. 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 -
    Answer is :- 30KHz
60. The output of a class B
    amplifier -
    Answer is :- consists of positive half cycles only
61. An amplifier with negative
    feedback
    Answer is :- all of the above
62. What changes would be
    necessary in block C if FM signals are to be received -Answer is :- A FM detector would be required
63. The main disadvantage of Diode-Transistor logic (DTL)
    is its-
    Answer is :- slower speed
64. Time delay Dt
    in digital signals in an SIS O shift register is given by –
    Answer is :- Dt
    = N ´ 1/Fc
65. 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)Answer is :- y and 0
66. Basic memory cell of dynamic RAM consists of –
    Answer is :- a transistor acting as a capacitor
67. The 2’s complement of 1000₂ is –
    Answer is :-1000
68. Master slave flip-flop is made up of –
    Answer is :-two flip flops connected in series
69. Number of nybbles making one byte is –Answer is :- 2
70. The intrinsic impedance of free space-
    Answer is :-is independent of frequency
71. A system consists of 12 poles and 2 zeroes. Its high
    frequency asymptote in its magnitude plot has a slope of -Answer is :- –200 dB/decade
72. In a unity feed back control system the open loop
    transfer function is The closed loop transfer unit will have pole at –Answer is :-–2, +j1,-j1
73. In a compensating network the transfer function is of
    the form If this is a phase log network
    the value of should be –
    Answer is :- between 0 and 1
74. Considering the conditions-1. High loop gain
    2. Less ringing3. Greater damping
    4 Negative dB gain marginSystem stability requirements would include
    Answer is :-2, 3 and 4
75. A typical control system is shown.Assuming
    R(s)=1/5 the steady state errors is given
    by
    Answer is :- zero
76. The centre and radius
    of M of circles are given respectively by
    Answer is :-
77. The open –loop
    transfer function for a unity feedback system is –what is the steady state
    error if the input is,r(t) = (2 + 3t + 4t²)
    u(t)
    Answer is :- 1
78. The correct sequence of steps required to improve system stability is –
    Answer is :-Use negative feedback, reduce gain, insert derivative action.

79. In the equatorial plane
    only Geosychronous satellite are launched because it is the only plane which
    provides –
    Answer is :- stationary satellite

80. Radio Broadcasting is an
    example of –
    Answer is :- frequency multiplexing

81. PAM signals can be demodulation by using a –
    Answer is :- A clipper circuit by a LPF
82. In an FDM receiver channels can be separated by using
    –
    Answer is :- AND gates
83. The most common modulation system used for telegraphy
    is-
    Answer is :-
    frequency shift keying
84. Use of varoctor diode in generation of modulated
    segial be-
    Answer is :-
    FM generation only
85. In colour picture tube shadow mask is used to-Answer is :- increase screen brightness
86. The circuit that separates composite video warefore from the sync
    pulses is-Answer is :- a
    sawtooth current
87. Band width of microwaves is-Answer is :-
    1GHz -10³ GHz
88. In transverse Magnetic mode-
    Answer is :- no magnetic line is in direction of propagation

89. Signal transmission in sky
    wave propagation is due to –
    Answer is :- Reforction of wave

90. According to Barkhausen
    Criterion Phase shift of signal should be –
    Answer is :- 360⁰

91. . The transmission does not
    have -

    Answer is :-
    Partition noise

92. Varoctor diode has non
    linearity of -
    Answer is :- capacitance

93. Scattering matrix equation
    for directional coupler is –

    Answer is :-

     

94. Noise figure is calculated
    as –
    Answer is :- i/p S/N Ratio / O/P S/N
    Ratio

95. You can determine quickly the effect of adding poles
    and zeros by –
    Answer is :- Bode plot
96. The polar plot of G(S) = intercepts real axis at w
    = w_o.
    Then, the real part and w_o
    are given by-Answer is :-
    –5, 1
97. Laplace transform F (s)
    of a function f (E) is given byThe initial and final
    values of F (t) will be respectively-
    Answer is :-10 and zero

98. A satellite link uses
    different frequencies for receiving and transmitting in order to –
    Answer is :- avoid interference between
    its powerful transmitted signals and weak in coming signal

99. The first determining
    factor in selecting a satellite system is its-
    Answer is :- Coverage area

100. Equalizing pulses in TV are sent during-
     Answer is :-vertical blanking
101. The son seems to have ——– from his father a
     somewhat gloomy and moody manner-
     Answer is :-inherited
102. Essayist works with words as sculptor with-
     Answer is :- stone
103. What is a collection of sheep called ?
     Answer is :- flock
104. Join these sentences meaningfully by choosing the
     correct alternative from the following :You can buy a book.
     You can read it.
     Answer is :- and
105. What is the opposite of Asperity –
     Answer is :- superiority
106. The Election Commission functions under-
     Answer is :-None of these
107. Article 352 of Indian Constitution needs to be
     revoked in case-
     Answer is :- Emergency is declared
108. Radio-activity was first discovered by-Answer is :- Becquerel
109. Ninth Plan in India ranges from-
     Answer is :- 1997-2002
110. How much electricity does India propose to generate
     through nuclear power by the year 2000 AD?
     Answer is :- 10,000 MW
111. In which year did the fall of Bastille take place?
     Answer is :- 1789
112. To form a quorum how many members of the Lok Sabha
     or Rajya Sabha should be present?
     Answer is :- 1/10th of total membership
113. How may countries are non-permanent members of the
     Security Council?
     Answer is :- 10
114. The International Date Line is represented by-
     Answer is :- 180⁰ meridian
115. India’s first satellite was launched from-
     Answer is :- A Soviet cosmodrome
116. Name the author of the famous book
     “Politics”-Answer is :- Aristotle
117. “Guernica” is Picasso’s painting on-Answer is :- The Spanish Civil War
118. The object of the Supreme Court’s
     Keshvanand Bharati ruling is -Answer is :- To put a limit on Parliament’s amendatory powers
119. Which country in July ‘99 officially announced
     mastering of indigenously developed neutron bomb technology?
     Answer is :- China
120. Shifting cultivation is commonly used in which of
     the following states?
     Answer is :-Nagaland
     

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