A Best Way To Crack Gorenment Job Exams

ECE Objective Questions { Power Semiconductor Devices and Their Applications }

57. UJT when used for triggering an SCR, has wave form,
A. sine wave
B. square wave
C. saw tooth wave
D. trapezoidsl

58. A resistor connected across the gate and cathode of a thyristor increases its
A. turn offtime
C. noise immunity
D. holding current

59. Inverter converts
A. dc to ac
B. ac to ac
C. dc to dc
D. ac to ac

60. In series connected thyrstors
A. L, is used for tuning out junction capacitance
B. L & C is used for filtering out the ripple
C. R, C iscalled a snubber act.di
D. L is intended to increase ? at switch dt on

61. When a thyristor and transistor as a switch are compared, true statement is
A. thyristor requires turn off circuit while transistor does not
B.the voltagedrop of thyristor is less than transistor
C. thyristor requires a continuous gate current
D. transistor does not draw continuously base current

62. In dc choppers, the waveforms for input and output voltages are respectively
A. both discontinuous
B. both continuous
C. continuous, discontinuous
D. discontinuous, continuous

63. In dc choppers, per unit apple is maximum whenduty cycle a is

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