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BSNL JTO Exam paper

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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 V_g – I_g

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) V_s, P
b) Vs/2, P
c) 2V_s, 2P
d) 2V_s, P
Answer is :- 2V_s, 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 I_CEO

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

56. What changes would be necessary in block C if FM signals are to be received -
a) Block becomes redundant
b) A FM detector would be required
c) A high frequency signal generator
1d) An additional local oscillator will be needed
Answer is :- A FM detector would be required

57. The main disadvantage of Diode-Transistor logic (DTL) is its-
a) greater speed
b) slower speed
c) average speed
d) none of the above
Answer is :- slower speed

58. Time delay Dt in digital signals in an SIS O shift register is given by –
a) Dt = N ´ Fc
b) Dt = N ´ 1/Fc
c) Dt = 1/N ´ Fc
d) Dt = N ¸ 1/Fc
Answer is :- 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 0
b) y and 1
c) 0 and y
d) 1 and y
Answer is :- y and 0

60. Basic memory cell of dynamic RAM consists of –
a) a flip flop
b) a transistor acting as a capacitor
c) a transistor
d) a capacitance
Answer is :- a transistor acting as a capacitor

61. The 2’s complement of 10002 is –
a) 0111
b) 0101
c) 1000
d) 0001
Answer is :-1000

62. Master slave flip-flop is made up of –
a) two flip flops connected in series
b) two flip flops connected in parallel
c) a debouncer circuit
d) a-D- latch
Answer is :-two flip flops connected in series

63. Number of nybbles making one byte is –
a) 2
b) 4
c) 8
d) 16
Answer is :- 2

64. The intrinsic impedance of free space-
a) is independent of frequency
b) decreases with increase of frequency
c) increases with increase of frequency
d) varies as square root of frequency
Answer is :-is independent 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/decade
b) –240 dB/decade
c) –230 dB/decade
d) –320 dB/decade
Answer is :- –200 dB/decade

66. Considering the conditions-
1. High loop gain 2. Less ringing 3. Greater damping 4 Negative dB gain margin
System stability requirements would include?

a) 1 and 3
b) 1, 2 and 3
c) 1 and 4
d) 2, 3 and 4
Answer is :-2, 3 and 4

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