Previous 50 << 51-100 >> Next 150
UNIT I - Introduction to Electronics MCQs 51-100
51.A half wave rectified sinusoidal waveform has a peak voltage of 12V. Its average value and rms value of the fundamental components are; respectively given by
a. 15/p V, 7.5 V
b. 20/p V, 10/Ö2 V
c. 12/p V, 6 V
d. none of these
Ans: c
52. In a bridge rectifier circuit we use
a. no centre-tapping and diode having peak inverse voltage Vm
b. no centre tapping and diode having inverse voltage 2Vm
c. centre tapping and diode having reverse voltage Vm
d. centre- tapping and diode having reverse voltage 2Vm
Ans: a
53.A device converting a.c. to d.c. is called
a. comparator
b. inverter
c. rectifier
d. regulator
Ans: c
53. PIV rating of diode in a bridge rectifieris
a. Vm
b. 2Vm
c. Vm/2
d. none of these
Ans: a
54. In HWR the peak value of ac voltage across secondary of transformer is 20√2 V if no filter circuit is used, the maximum d.c. voltage across the load will be
a. 28.28 V
b. 14.14 V
c. 20 V
d. 9 V
Ans: d
55. If Vm is the peak voltage across secondary of transformer in HWR (without any filter circuit. , then the maximum voltage on reverse biased diode is
a. Vm
b. 1/2Vm
c. 2Vm
d. none of the above
Ans: a
56. If Vm is the peak voltage across secondary of transformer in HWR ,if we use shunt capacitor filter, the maximum voltage that occurs on reverse biased diode is
a. Vm
b. 1/2Vm
c. 2Vm
d. none of the above
Ans: a
57. In Center tap FWR Vm is the peak voltage between center tap and one end of secondary, the maximum voltage that occurs on reverse biased diode is
a. Vm
b. 1/2Vm
c. 2Vm
d. none of the above
Ans: c
58. In HWR the load current flowsfor
a. the complete cycle of inputsignal.
b. only for positive half cycle of inputsignal.
c. less than half cycle of inputsignal.
d. more than half cycle but lass than complete cycle of inputsignal.
Ans: b
59.What is the dc output voltage of an unfiltered half-wave rectifier whose peak output voltage is 9.8 V?
a. 6.23 V
b. 19.6 V
c. 9.8 V
d. 3.1 V
Ans : d
60.What is the frequency of the capacitor ripple voltage in a full-wave rectifier circuit if the frequency of the transformer secondary voltage is 60 Hz?
a. 60Hz
b. 50 Hz
c. 20 Hz
d. this is impossible to determine
Ans: c
61. In a full-wave rectifier, the dc load current equals 1A. How much dc current is carried by each diode?
a. 1⁄2 A
b. 1 A
c. 2 A
d. 0 A
Ans: a
62.A half wave rectified sinusoidal waveform has a peak voltage of 12V. Its average value and rms value of the fundamental components are; respectively given by
a. 15/p V, 7.5 V
b. 20/p V, 10/Ö2 V
c. 12/p V, 6 V
d. none of these
Ans: c
63. In a bridge rectifier circuit we use
a. no centre-tapping and diode having peak inverse voltage Vm
b. no centre tapping and diode having inverse voltage 2Vm
c. centre tapping and diode having reverse voltage Vm
d. centre- tapping and diode having reverse voltage 2Vm
Ans : a
64. In a full wave rectifier with R-C filter, the conduction angle of the diode is
a. 0
b. less than 180
c. Equal to 180
d. More than 0
Ans: b
65. The average value of a half wave rectified voltage with a peak value of 200V is
a. 63.7V
b. 127.3 V
c. 141V
d. 0V
Ans : a
66.When a 60 Hz sinusoidal voltage is applied to the input of a half wave rectifier, the output frequency is
a. 120 Hz
b. 30 Hz
c. 60 Hz
d. 0 Hz
Ans : c
67. The peak value of the input to a half wave rectifier is 10V. the approximate peak value of the output is
a. 10 V
b. 3.18 V
c. 10.7 V
d. 9.3 V
Ans :d
68. The average value of full wave rectified voltage with a peak value of 75V is
a. 53 V
b. 47.8 V
c. 37.5 V
d. 23.9 V
Ans :b
9.When a 60Hz sinusoidal voltage is applied to the input of a full wave rectifier, the output frequency is
a. 120 Hz
b. 60 Hz
c. 240 Hz
d. 0 V
Ans : a
70. The total secondary voltage in a centre tapped full wave rectifier is 125 V rms. Neglecting the diode drop, the rms output voltage is
a. 125V
b. 177 V
c. 100 V
d. 62.5 V
Ans : d
71.When the peak output voltage is 100V, the PIV for each diode in a centre- tapped full wave rectifier is( neglecting the diode drop.
a. 100 V
b. 200 V
c. 141 V
d. 50V
Ans : b
72.When the rms output voltage of a bridge full- wave rectifier is 20V, the peak –inverse voltage across the diodes is ( neglecting the diode drop.
a. 20 V
b. 40 V
c. 28.3 V
d. 56.6 V
Ans : c
73.A 60 V peak full wave rectified voltage is applied to a capacitor input filter. If f=120 Hz, RL =10K and C= 10 μF, the ripple voltage is
a. 0.6 V
b. 6 mV
c. 5 V
d. 2.88 V
Ans : d
74. If one of the diodes in a bridge full wave rectifier opens, the output is
a. 0V
b. one-fourth the amplitude of the input voltage
c. a half wave rectified voltage
d. a 120Hz voltage
Ans : c
75. If you are checking a 60 Hz full wave bridge rectifier and observe that the output has 60Hz ripple
a. the circuit is working properly
b. there is an open diode
c. the transformer secondary is shorted
d. the filter capacitor is leaky
Ans : b
76.With a half wave rectified voltage across the load resistor, load current flows for what part of a cycle?
a. 0 degree
b. 90 degree
c. 180 degree
d. 360 degree
Ans : c
77. Suppose line voltage may be as low as 105 V rms or as high as 125 V rms in a half wave rectifier. With a 5 : 1 step down transformer, the minimum peak load voltage is closestto
a. 21 V
b. 25 V
c. 29.7 V
d. 35.4 V
Ans : c
78. The voltage out of a bridge rectifier is a
a. half wave signal
b. full wave signal
c. bridge rectified signal
d. sine wave
Ans : b
79.What is the peak load voltage in a full wave rectifier if the secondary voltage is 20 V rms?
a. 0 V
b. 0.7 V
c. 14.1 V
d. 28.3 V
Ans : c
80.We want a peak load voltage of 40 V out of a bridge rectifier. What is the approximate rms value of secondary voltage?
a. 0 V
b. 14.4 V
c. 28.3 V
d. 56.6 V
Ans : c
81.With a full wave rectified voltage across a load resistor, load current flows for what part of a cycle?
a. 0 degree
b. 90 degree
c. 180 degree
d. 360 degree
Ans : d
82.With the same secondary voltage and filter, which of the following has the mostripple?
a. half wave rectifier
b. full wave rectifier
c. bridge rectifier
d. impossible to say
Ans : a
83.With the same secondary voltage and filter which of the following produces the least load voltage?
a. half wave rectifier
b. full wave rectifier
c. bridge rectifier
d. impossible to say
Ans : a
84. If the filtered load current is 10 mA, which of the following has a diode current of 10mA?
a. half wave rectifier
b. full wave rectifier
c. bridge rectifier
d. All above
Ans : d
85. The diodes in a bridge rectifier each have a maximum dc current rating of 2 A. this means the dc load current can have maximum value of
a. 1 A
b. 2 A
c. 4 A
d. 8 A
Ans : b
86. Efficiency of half wave rectifier is
a. 81.2 %
b. 40.6 %
c. 45.6 %
d. 82.1 %
Ans : b
87. Ripple factor of half wave rectifier is
a. 2.122
b. 1.112
c. 1.211
d. 2.11
Ans : c
88. Efficiency of full wave rectifier is
a. 81.2 %
b. 40.6 %
c. 45.6 %
d. 82.1 %
Ans : a
89. Ripple factor of full wave rectifier is
a. 0.122
b. 0.4
c. 0.48
d. 0.05
Ans : c
90. Efficiency of bridge rectifier is
a. 81.2 %
b. 40.6 %
c. 45.6 %
d. 82.1 %
Ans : a
91. Ripple factor of bridge rectifier is
a. 0.122
b. 0.4
c. 0.48
d. 0.05
Ans : c
92. In a full-wave rectifier, the current in each of the diodes flows for
a. the complete cycle of the input signal
b. half cycle of the inputsignal
c. less than half cycle of the inputsignal
d. zero time
Ans : b
93. To minimize the ripple content in the circuit
a. Diode circuit is used
b. filter circuit is used
c. bridge circuit is used
d. none of the above
Ans: b
94.What is the frequency of the capacitor ripple voltage in a full-wave rectifier circuit if the frequency of the transformer secondary voltage is 60 Hz?
a. 60Hz
b. 50Hz
c. 120Hz
d. this is impossible to determine
Ans: c
95. The ideal dc output voltage of a capacitor input filter is equal to
a. the peak value of the rectified voltage
b. the average value of the rectified voltage
c. the rms value of the rectified voltage
d. none of the above
Ans: a
96.A certain power supply filter produces an output with a ripple of 100 mV peak-to-peak and dc value of 20V. the ripple factoris
a. 0.05
b. 0.005
c. 0.0005
d. 0.02
Ans: b
97. Line regulation is determined by
a. load current
b. zener current and load current
c. changes in load resistance and output voltage
d. changes in output voltage and input voltage
Ans: d
98. Load regulation is determined by
a. changes in load current and input voltage
b. changes in load current and output voltage
c. changes in load resistance and input voltage
d. changes in zener current and load current
Ans: d
99. If you are checking a 60 Hz full wave bridge rectifier and observe that the output has 60Hz ripple
a. the circuit is working properly
b. there is an open diode
c. the transformer secondary isshorted
d. the filter capacitor isleaky
Ans: b
100. Types of filter are
a. Capacitor input filter
b. choke input filter
c. resister input filter
d. both A and B
Ans: d
Post a Comment