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                                             BSNL JTO Exam 2011

      PART I

1.    Modern capacitors which have high capacitance in small size use a dielectric of 

        (A) paper     (B) rubber    (C) ceramic    (D) Mylar

2.    The Maximum spectral response of the germanium and silicon is in the 

        (A) infrared region    (B) ultraviolet region    (C) visible region    (D) x-ray region

3. For an insulating material, dielectric strength and dielectric loss should be respectively

        (A) high and high    (B) low and high    (C) high and low    (D) low and low.

4. In a distortion factor meter, the filter at the front end is used suppress

        (A) odd harmonics    (B) even harmonics    (C) fundamental component    (D) dc component

5. The coefficient of coupling between two air core coils depends on

        (A) mutual inductance between two coils only    (B) self inductances of the two coils only     (C) mutual inductance 
         and self inductances of the two coils    (D) none

6. For a parallel plate capacitor which  is being charged out of the following the incorrect statement is 

        (A) Energy stored in the capacitor does not enter it through the connecting wire through the space around            
              the wires and plates of capacitor.

        (B) Rate at which energy flows into this volume is equal to the integration of the poynting vector over the boundary 
             of the volume between the plates.

        (C) The poynting vector points everywhere radially outward of the volume between plates.

        (D) The poynting vector points everywhere radially  in to the volume between the plates.

7. The presence of alkali oxides in alumino silicate ceramics is likely to result in dielectric breakdown due to

        (A) Polarization     (B) Conductivity    (C) Structural homogeneties     (D) Ionization

8. Which of the following will  serve as a donor impurity in silion

        (A) Boron    (B) Indium    (C) Germanium    (D) Antimony

9. Electrical contact materials used in switches, brushes and relays must possess

        (A) high thermal conductivity and high melting point    (B) Low thermal conductivity and low melting point     

        (C) High thermal conductivity and low melting point    (D) Low thermal conductivity and high melting point.

10. An SCR can only be turned off via it's

        (A) cathode    (B) anode    (C) gates    (D) none

11. Gold is often diffused into silicon PN junction devices to 

        (A) increase the recombination rate    (B) reduce the recombination rate    

        (C) make silicon a direct gap semiconductor    (D) make silicon semi-metal

12 With n nodes and b branches a network will have

        (A) (b+n) links    (B) b - n +1 links    (C) b -n-1 links    (D) b + n + 1 links

13. When a network has 10 nodes and 17 branches in all then the number of node pair voltages would be 

        (A) 7    (B) 9    (C) 10    (D) 45

14. In any atom the potential energy of an orbiting electron is

        (A) always positive    (B) always negative  

         (C) sometime positive, sometime negative     (D) numerically less then its kinetic energy.

15. A delition MOSFET differs from a JFET in the sense that it has no

        (A) channel     (B) gate    (C) P-N junctions    (D) substrate

16. The advantage of a semiconductor strain gauge cover the wire round strain guage is that

        (A) it is more sensitive    (B) it is more linear    (C) it is less temperature dependent    (D) it's cost is low

17. Barrier potential in a P-N junction is caused by 

        (A) thermally generated electrons and holes    (B) diffusion of majority carriers across the junction    

        (C) migration of minority carriers across the junction    (D) flow of drift current.

18. When an NPN transistor is properly biased then most of the electrons from the emitter

        (A) recombine with holes in the base    (B) recombine in the emitter itself    

        (C) pass through the base to the collector    (D) are stopped by the junction barrier

19. The deplition voltage for silicon diode at m0  bias is 

        (A) 0.5 volt    (B) 0.3 volt    (C) 0.7 volt    (D) 1.1 volt

20. A UJT can

        (A) be triggered by any one of it's three terminals    (B) not be triggered   

         (C) be triggered by two of its three terminal only     (D) be triggered by all of  its terminals only.

21. The energy of electric field due to a spherical charge distribution of radius r and inform charge density in vacuum is

       

22. Maxwells divergence equation for the magnetic field is given by

                __    __                          __   __

        A.    ?*   B   = 0            B.   ? . B = 0

                 __    __                         __   __

        C.     ?*  B   = p            D.   ? . B  =  p

23. When a short grounded vertical antenna has a length L which is 0.05 1 at frequency f and if it's radiation resistances 
       at f is R Ohms, then its radiation resistance at a frequency 2f will be 

        (A) R/2 ohms    (B) R ohms    (C) 2R ohms    (D) 4R ohms

24.In a cylindrical cavity resonator, the two modes which are degenerate would include

        (A) TE111 and TM111    (B) TE011 and TM011    (C) TE022 and TM111    (D) TE111 and TM011

25. When an antenna of input resistance 73 ohm is connected to a 50-ohm line and if the losses are ignored then its 
       efficiency will be nearly

        (A) 0.19    (B) 0.81    (C) 0.97    (D) 1.19

26.The transformer utilization factor of full wave bridge rectifier is 

        (A) 0.812    (B) 0.286    (C) 0.693    (D) 0.782

27. When a dominant mode wave guide not terminated in its characteristic impedance is excited with a 10 GHZ signal 
       then if d is the distance between two successive minima of the standing wave in the guide then

        (A) d = 1.5 cm    (B) d is less then 1.5 cm    (C) d is greater then 1.5 cm    (D) d = 3cm

28. A two port network having a 6 dB loss will give 

        (A) an output power which is one - quarter of the input power    (B) an output power which is one -                   
              half of the input power

        (C) an output  voltage which is 0.707 of the input voltage.    (D) an output power which is 0.707                         
              of the input power.

29. While transporting a sensitive galvanometer

        (A) the terminals are kept shorted    (B) critical damping resistance is connected across the terminals    

        (C) the terminals are kept open circuited    (D) it does not matter as to what is connected across the terminals.

30. A T type attenuator is designed for an attenuation of 40 dB and terminating resistance of 75 ohms.                  
      Which of the following values represent full series arm R1 and shunt arm R2?

         1.R1 = 147 Ω    2. R1 = 153 Ω    3. R1 = 1.5 Ω     4.  R1= 3750 Ω

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

31. For a transmission line, the characteristic impedance with inductance 0.294  µH/m and capacitance 60pF/m is

        (A) 49 Ω     (B) 60 Ω   (C) 70 Ω   (D) 140 Ω

32. When the graph of a network has six branches with three tree branches then the minimum number                          
        of equations required for the solution of the network is

        (A) 2    (B) 3    (C) 4    (D) 5

33. Consider the following statement for a 2-port network

        1.  Z11 =Z22    2. h12 = h21    3.Y12 = -Y21    4.BC - AD = -1

        then the network is reciprocal if and only if

        (A) 1 and 2 are correct    (B) 2 and 3 are correct    (C) 3 and 4 are correct    (D) 4 alone is correct.

34. As a network contains only independent current sources and resistors then if the values of all                            
      resistors are doubled then the values of the node voltages are

        (A) will become half    (B) will remain unchanged    

        (C) will become double    (D) cannot be determined unless the circuit configuration and the values                        
             of the resistors are known.

35. A iron cored choke is a 

        (A) Linear and active device (B) Non linear and passive device  (C) Active device only  (D) Linear device only

36. Poynting vector wattmeter is based on

        (A) Seebeck effect    (B) Ferranti effect    (C) Induction effect    (D) Hall effect

37. Which one of the following is not a transducer in the true sense?

        (A) Thermocouple    (B) Piezoelectric pick-up    (C) Photo voltaic cell     (D) LCD.

38. The term used to denote a static device that converts ac to dc, de to ac, dc to dc or ac to ac is

        (A) Converter system    (B) Inverter    (C) Chopper    (D) Thyristor

39. When a dipole antenna of 1/8 length has an equivalent total resistance of 1.5 Watt then the                             
       efficiency of the antenna is

        (A) 0.89159%    (B) 8.9159%    (C) 89.159%    (D) 891.59%

40. In commercial FM broadcasting, the maximum frequency deviation is normally

        (A) 5 KHz    (B) 15 KHz    (C) 75 KHz    (D) 200 KHz

41. Weins bridge is used for measurement of frequency in the applied voltage waveform is measurement                       
      of frequency in the applied voltage waveform is

        (A)sinusoidal    (B) square    (C) rectangular    (D) triangular

42.Strain gauge is 

        (A) not a transducer    (B) an active transducer    (C) not an electronic instrument

43.A high Q coil has

        (A) large band width    (B) high losses    (C) low losses    (D) flat response

44. In the case of an instrument reading of 8.3 V with a 0 to 150 voltmeter having a guaranteed accuracy of                
      1% full scale reading, the percentage limiting error is

        (A) 1.810%    (B) 0.181%    (C)12.45%    (D) 0.0018%

45. The 'h' parameter equivalent circuit of a junction transistor is valid for

        (A) High frequency, large signal operation    (B) High frequency, small signal operation    (C) Low frequency,  
               large signal operation.

46. A system is causal if the output of any time depends only on

        (A) Values of input in the past and in the future    (B) Values of input at that time and in the past    

        (C) Values of input at that time and in the future    (D) none

47. Form the hot metal surface electrons escape because

        (A) of change of state from metal to gas due to heat.    (B) of change of state from gas to metal    

        (C) the energy supplied is greater than the work function    (D) the energy is greater than Fermi level

48. The most common device used for detection in radio receivers is

        (A) amplifier    (B) triode    (C) diode    (D) transistor

49. In a full wave rectifier the negative point in a circuit is 

        (A) cathode    (B) anode    (C) The central tap on the high voltage secondary     (D) plate.

50.Negative feedback amplifier has a signal corrupted by noise as its input. The amplifier will

        (A) Amplify the noise as much as the signal    (B) Reduce the noise    (C) Increase the noise                              
         (D) Not effect the noise

      PART - II

51. It is an unidirectional device that blocks the current flow from cathode to anode

        (A) SCR    (B) PCR    (C) VCR    (D) DCR

52. An ideal constant current source is connected in series with an ideal constant voltage source. Considering together 
      the combination will be a 

        (A) constant voltage source    (B)constant current source    

        (C) constant voltage and a constant current source or a constant power source.    (D) resistance

53. Anode current in an thyristor is made up of 

        (A) electrons only    (B) electrons or holes    (C) electrons and holes    (D) holes only

54. For a pulse transformer, the material used for its core and the possible turn ration from primary to secondary are 
       respectively

        (A) ferrite : 20 : 1    (B) laminated iron : 1 :1    (C) ferrite : 1 : 1    (D) powered iron : 1: 1

55. A converter which can operate in both 3 pulse and 6 pulse mode is a 

(A) 1 phase full converter    (B) 3 phase half wave converter    (C) 3 phase semi converter    (D) 3 phase full converter.

56. A single phase CSI has capacitor C as the load.  For a constant source current, the voltage across the capacitor is

        (A) square wave    (B) triangular wave    (C) step function    (D) pulsed wave

57. a single phase full wave midpoint thyristor converter uses a 230/200V transformer with centre tap                          
      on the secondary side. The P.I.V per thyristor is

        (A) 100V    (B)141.4V    (C)200V    (D)282.8V

58. In dc choppers for chopping period T, the output voltage can be controlled by FM by varying

        (A) T keeping Ton constant    (B) Ton keeping T constant   

         (C) Toff keeping T constant    (D) None of the above

59.An ideal power supply consist of

        (A) Very small output resistance    (B) Zero Internal resistance  

        (C) Very large input resistance    (D) Very large output resistance

60. The linearity error for a digital input is indicated by

        (A) ξ     (B) γ    (C) η    (D) ε

61. In the 8421 BCD code the decimal number 125 is written as 

        (A) 1111101    (B) 0001 0010 0101    (C) 7D    (D) None of the bove

62. Match the given feedback circuit with its proper nomenclatures

        

        (A) Current series feedback    (B) Current shunt feedback    

        (C) Voltage series feedback    (D) Voltage shunt feedback

63. Class A amplifier is used when

         (A) No phase inversion is required    (B) Highest voltage gain is required   

         (C) dc voltages are to be amplified    (D) Minimum distortion is desired.

64. Identity the correct match for the given transister

         

        (A) Enhancement type P channel MOSFET    (B) Depletion type N channel MOSFET    

        (C) Enhancement type N channel MOSFET    (D) Depletion type P channel MOSFET

65. In case a signal band limited to fermimeter is sampled at a rate less than 2 fermimeter, the constructed signal will be

        (A) Distortionless    (B) Small in amplitude    (C) Having higher frequencies suppressed     (D) Distorted

66.IC which has quad 2 input AND gates

        (A) 7411    (B) 7404    (C)7400    (D) 7408

67. Registers in which data is entered or taken out in serial form are referred as

        (A) left shift register    (B) right shift register    (C) shift registers    (D) none of the above

68. The expression ABC can be simplified to

           __ __ __

    A.    A  B   C                     B.   AB+BC+CA

                    __                               __   __   __     

    C.    AB+ C                         C.    A + B + C

69. Read the following

        (i) Routh Herwitz's criterion is in time domain

        (ii)Root locus plot is in time domain

        (iii) Bode plot is in frequency domain

        (iv) Nyquist criterion is in frequency domain.

        (A) 2,3 and 4 are correct    (B) 1,2 and 3 are correct    (C) 3 and 4 are correct     (D) all four are correct

70. Register and counters are similar in the sense that they both

         (A) count pulses    (B) store binary operation    (C) shift operation   

         (C) made from an array of flip flops and gates integrated on a single chip.

71. In D/A converter, the resolution required is 50mv and the total maximum input is 10v. The number of                    
      bits required is 

        (A) 7    (B) 8    (C) 9    (D) 200

feedback