### Solved Sample Paper For BSNL JTO Examination (Part -1)

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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