BSNL JTO Placement Papers

19/06/2011 17:33

Solved Sample Paper For BSNL JTO Examination

 

1. One of the following statement which is true for relative dielectric constant is -
a) It is dimensionless
b) It is not equal to unity for vacuum
c) It?s value for all substances is less than one
d) None
Answer is :- It is dimensionless


2. Pure metals generally have-
a) high conductivity and low temperature coefficient
b) high conductivity and large temperature coefficient
c) low conductivity and zero temperature coefficient
d) low conductivity and high temperature coefficient
Answer is :- high conductivity and large temperature coefficient


3. For small size, high frequency coils, the most common core material is
a) Air
b) Ferrite
c) Powdered ion
d) Steel
Answer is :- Air


4. For an abrupt junction Varactor diode, the dependence of device capacitance (C) on applied reverse bias (V) is given by-
a) C a V1/3
b) C a V-1/3
c) C a V1/2
d) C a V-1/2
Answer is :- C a V-1/3

5. A superconductor is a-
a) A material showing perfect conductivity and Meissner effect below a critical temperature
b) A conductor having zero resistance
c) A perfect conductor with highest dimagnetic susceptibility
d) A perfect conductor which becomes resistive when the current density through it exceeds a critical value
Answer is :-A material showing perfect conductivity and Meissner effect below a critical temperature

6. When a semiconductor based temperature transducer has a temperature coefficient of ?2500 mV/0C then this transducer is indeed a-
a) Thermistor
b) Forward biased pn junction diode
c) Reverse biased pn junction diode
d) FET
Answer is :- Forward biased pn junction diode

7. The location of lightning arrestor is -
a) Near the transformer
b) Near the circuit breaker
c) Away from the transformer
d) None
Answer is :- Near the transformer


8. Time constant of an RC circuit increases if the value of the resistance is -
a) Increased
b) Decreased
c) Neither a nor b
d) Both a and b
Answer is :- Increased


9. Intrinsic semiconductors are those which -
a) Are available locally
b) Are made of the semiconductor material in its purest from
c) Have more electrons than holes
d) Have zero energy gaps
Answer is :- Are made of the semiconductor material in its purest from


10. The primary control on drain current in a JFET is exerted by -
a) Channel resistance
b) Size of depletion regions
c) Voltage drop across channel
d) Gate reverse bias
Answer is :- Gate reverse bias


11. The electrical conductivity of metals which is expressed in ohm-1 m-1 is of the order of -
a) 1010
b) 105
c) 10-4
d) 10-6
Answer is :- 105


12. When biased correctly, a zener diode ?
a) acts as a fixed resistance
b) has a constant voltage across it
c) has a constant current passing through it
d) never overheats
Answer is :- has a constant voltage across it


13. The current amplification factor adc is given by ?
a) IC/IE
b) IC/IB
c) IB/IC
d) IB/IC
Answer is :- IC/IE


14. Compared to bipolars, FETs have-
a) high input impedance
b) low input impedance
c) same input impedance
d) none
Answer is :- high input impedance


15. The source-drain channel of JFET is -
a) ohmic
b) bilateral
c) unilateral
d) both a and b
Answer is :- both a and b


16. diac is equivalent to a -
a) Pair of SCRs
b) Pair of four layer SCRs
c) Diode and two resistors
d) Triac width
Answer is :- Pair of four layer SCRs


17. 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/cm3
b) 103/ cm3
c) 1010/ cm3
d) 1012/ cm3
Answer is :- 103/ cm3


18. 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 law
b) Norton?s theorem
c) Thevenin?s theorem
d) Superposition theorem
Answer is :- Superposition theorem


19. One of the following modes which has the characteristics of attenuation becoming less as the frequency is increased and is attractive at microwave frequencies of circular cylindrical wave guides is ?
a) TE1 mode
b) TM01 mode
c) TE01 mode
d) Higher order mode
Answer is :- TE01 mode


20. A two-port network is symmetrical if ?
a) z11z22 ? z12z21 = 1
b) h11h22 ? h12h21 = 1
c) AD ? BC = 1
d) y11y22 ? y12y21 = 1
Answer is :-AD ? BC = 1


21. For transmission line load matching over a range of frequencies, it is best to use a-
a) balun
b) broad band directional coupler
c) double stub
d) single stub of adjustable position
Answer is :- double stub


22. 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 network
b) as an RC driving point impedance
c) as an RC driving point admittance
d) only by an RLC network
Answer is :- only by an RLC network


23. 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 C
b) L and C
c) R and L
d) R, L and C
Answer is :- L and C


24. For a two port reciprocal network, the output open circuit voltage divided by the input current is equal to ?
a) B
b) Z12
c) ?
d) h12
Answer is :- Z12


25. 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.
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.


26. The frequency modulated (FM) radio frequency range is nearly -
a) 250 ?300 MHz
b) 150 ? 200 MHz
c) 90 ? 105 MHz
d) 30-70 MHz
Answer is :-90 ? 105 MHz


27. In an underground cable the distortion in the transmission of carrier frequency can be eliminated by using -
a) Inductive loading
b) Resistive loading
c) Capacitive loading
d) Shielding
Answer is :- Inductive loading


28. The characteristic impedance of a transmission line with inductance 0.294 mH /m and capacitance 60 pF/m is -
a) 49 W
b) 60 W
c) 70 W
d) 140 W
Answer is :- 70 W


30. For a quarter wavelength ideal transmission line of characteristic impedance 50 ohms and load impedance 100 ohms, the input impedance will be ?
a) 25W
b) 50W
c) 100W
d) 150W
Answer is :- 25W


31. 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 m
b) 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
Answer is :- directly proportional to r and inversely proportional to f and m


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 0
b) 1.44560
c) 2.44560
d) 3.44560
Answer is :- 2.44560


33. Lens antennas used for microwaves are usually made of -
a) Polystyrene
b) Glass of low refractive index
c) Paraboloid surfaces
d) Dielectric media having large refractive index
Answer is :- Polystyrene


34. One of the following types of instrument which is an electrometer is -
a) Electrodynamometer
b) PMMC
c) Electrostatic
d) Moving iron
Answer is :- Electrostatic


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 5A
b) An ac ammeter will read only 5A
c) A dc ammeter will read 10A
d) A dc ammeter will read zero
Answer is :- An ac ammeter will read less than 10A but more than 5A


36. When Q factor of a circuit is high, then -
a) power factor of the circuit is high
b) impedance of the circuit is high
c) bandwidth is large
d) none of these
Answer is :- none of these


37. The resolution of a logic analyser is -
a) the maximum number of input channels
b) the minimum duration of the glitch it can capture
c) it?s internal clock period
d) the minimum amplitude of input signal it can display
Answer is :- the minimum amplitude of input signal it can display


38. A memoryless system is ?
a) causal
b) not causal
c) nothing can be said
d) none
Answer is :- causal


39. An air capacitor is a ?
a) time variant
b) active device
c) time invariant
d) time invariant and passive device
Answer is :-time invariant and passive device


40. Thermistors are made of -
a) pure metals
b) pure insulators
c) sintered mixtures of metallic oxides
d) pure semiconductor
Answer is :- sintered mixtures of metallic oxides


41. Pirani gauge is used to measure ?
a) very low pressures
b) high pressures
c) pressures in the region of 1 atm
d) fluid flow
Answer is :- very low pressures


42. These circuits converts input power at one frequency to output power at a different frequency through one stage conversion ?
a) AC voltage controllers
b) Cyclo converters
c) Phase controlled rectifiers
d) Inverters
Answer is :-Cyclo converters


43. In a forward voltage Triggering thyristor changes from ?
a) off state to on state
b) on state to off state
c) on state to on state
d) off state to off state
Answer is :- off state to on 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 voltage
b) peak working off state forward voltage
c) peak working off state reverse voltage
d) peak non-repetitive off state forward voltage
Answer is :- peak working off state forward voltage


45. Gate characteristic of a thyristor-
a) is a straight line passing through origin
b) is of the type Vg = a + bIg
c) is a curve between Vg and Ig
d) has a spread between two curves of Vg ? Ig
Answer is :-has a spread between two curves of Vg ? Ig


46. A four quadrant operation requires-
a) two full converters in series
b) two full converters connected back to back
c) two full converters connected in parallel
d) two semi converters connected back to back
Answer is :-two full converters connected back to back


47. 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, P
b) Vs/2, P
c) 2Vs, 2P
d) 2Vs, P
Answer is :- 2Vs, 2P


48. In an enhancement type MOSFET the output V-I characteristics has ?
a) only an ohmic region
b) only a saturation region
c) only ohmic region at 10 W voltage value followed by a saturation region at higher voltages
d)an ohmic region at large voltage values preceded by a saturation region at lower voltages
Answer is :- only ohmic region at 10 W voltage value followed by a saturation region at higher voltages


49. The energy gap in a semiconductor -
a) increases with temperature
b) remains constant
c) slightly increase with temperature
d) decrease with temperature
Answer is :-decrease with temperature


50. In an electronic circuit matching means -
a) connecting a high impedance directly to low impedance
b) selection of components which are compatible
c) transferring maximum amount of signal between different kinds of circuits.
d) RC coupled stages
Answer is :-transferring maximum amount of signal between different kinds of circuits.


51. P channel FETs are less superior than N channel FETs because
a) They have higher input impedance
b) They have high switching time
c) They consume less power
d) Mobility of electrons is greater than that of holes
Answer is :- Mobility of electrons is greater than that of holes


52. Small increase in temperature in the CE connected transistor is the -
a) Increase in ICEO
b) Increase in ac current gain
c) Decrease in ac current gain
d) Increase in output resistance
Answer is :- Increase in ICEO


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 KHz
b) 30KHz
c) 10KHz
d) 40KHz
Answer is :- 30KHz


54. The output of a class B amplifier -
a) is distortion free
b) consists of positive half cycles only
c) is like the output of a full wave rectifier
d) comprises short duration current pulses
Answer is :- consists of positive half cycles only


55. An amplifier with negative feedback -
a) lowers its lower 3 dB frequency
b) raises its upper 3 dB frequency
c) increases its bandwidth
d) all of the above
Answer is :- all of the above

 

 

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Warm Regards,

Soumya Sourabha Patnaik(SSP)