Power Electronics Questions and Answers in Quiz Form 7 for Practice

91. For a buck converter to reduce the conduction losses in diode

1. A low on – resistance switch can be added in parallel
2. A high on – resistance switch can be added in series
3. A high on – resistance switch can be added in parallel
4. A low on – resistance switch can be added in series

92. For bidirectional operation of converters

1. A parallel combination of controllable switch and capacitor is used
2. A series combination of controllable switch and a diode is used
3. A parallel combination of controllable switch and a diode is used
4. A series combination of controllable switch and a capacitor is used

93. For similar carrier and modulating signals, the line current used in CSI is

1. Identical to line current in VSI
2. Identical to phase voltage in VSI
3. Identical to line voltage in a VSI
4. Identical to phase voltage in CSI

94. For sweptfrequency measurements, the input impedance of the mismatched transmission line would vary with frequency as the electrical length ofthe transmission line would

1. Remains same with change in frequency
2. Increase with frequency
3. Decrease with frequency
4. Either (a or b)

95. Harmonics in 3 phase inverters can be reduced by using

1. Active filter
2. Both passive and active filters
3. Passive filter
4. None of these

96. In a 3 phaseCSI, if the required line output voltages are balanced and 120 degreeout of phase, then the chopping angles are used to eliminate only theharmonics at frequencies

1. 7
2. 11
3. 5
4. All of these

97. In a load commutated DC – DC chopper, the capacitor has a

1. Symmetric rectangular voltage across itself
2. Symmetric trapezoidal voltage across itself
3. Symmetric triangular voltage across itself
4. Symmetric sinusoidal voltage across itself

98. In a three phase converter, the number of notches per cycle is

1. Three
2. Six
3. One
4. Nine

99. In a UJT, the p-type emitter is ……………. doped

1. Heavily
2. Moderately
3. Lightly
4. None of the above

100. In bipolar modulation, the carrier is symmetric about zero with amplitude equal to Cm, the PWM output

1. Switches between – 1 / 2 and + 1 / 2
2. Switches between – 1 and + 1
3. Zero
4. Switches between 0 and + 1

101. In current commutated DC-DC choppers, the voltage spike appears across the load when

1. The capacitance voltage adds to the supply voltage
2. Both (a and b)
3. Voltage across the commutating inductances collapses
4. None of these

102. In EMCsignal, the source delivers maximum power to the input of transmissionline when the transmission line input impedance

1. Greater than the source resistance
2. Smaller than the source resistance
3. Is equal to the source resistance
4. None of these

103. In radiative coupling, the emitter radiation field

1. Decays as R, where R is the separation distance between the emitter and the receptor
2. Decays as 1 / 2 R, where R is the separation distance between the emitter and the receptor
3. Decays as 1 / R, where R is the separation distance between the emitter and the receptor
4. Decays as 2R, where R is the separation distance between the emitter and the receptor

104. In single phase VSI, the harmonic which is not present is

1. 3rd
2. 5th
3. 2nd
4. 7th

105. LISN is a device used to measure conducted emissions. LISN stands for

1. Line impedance stabilization network
2. Line integrated stored network
3. Line integrated stabilization network
4. Laser integrated stabilization networking