power electronics MCQs – Page 9

Practise focused power electronics questions with marked answers for exam preparation and subject revision.

power electronics Mcqs
161. SCRs are used in series to meet_______________?
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A. low voltage demand

B. high current demand

C. low current demand

D. high voltage demand
162. Materials used in heat sink should have_____________?
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A. high melting point

B. large surface area

C. All of these

D. high thermal conductivity

163. Between the incoming and outgoing devices in voltage commutation
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A. Large overlapping takes place

B. Small overlapping operation

C. No overlapping operation

D. None of these

164. An ideal diode is___________?
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A. Unidirectional

B. Fixed voltage polarity

C. Only (a) and (c)

D. Bidirectional

165. The output current in PWM DC DC converters is equal to___________?
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A. Product of an average inductor current and a function of duty ratio

B. None of these

C. Average value of the output inductor current

D. Either A. or B.
166. During the commutation period in 3 phase converter, overlap time is____________?
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A. Dependent on the load current

B. Dependent on the voltage

C. Dependent on both the load current and load voltage behind the short circuit current

D. Independent on both the load current and load voltage

167. Single phase VSI are mainly used in___________?
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A. Multilevel configuration

B. Ups

C. Power supplies

D. All of these
168. AC power in a load can be controlled by using_____________?
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A. four SCRs in series

B. two SCRs in parallel opposition

C. three SCRs in series

D. two SCRs in series

169. In radiative coupling, the emitter radiation field_____________?
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A. Decays as 1 / R, where R is the separation distance between the emitter and the receptor

B. Decays as R, where R is the separation distance between the emitter and the receptor

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

D. Decays as 2R, where R is the separation distance between the emitter and the receptor

170. BCT is used for____________?
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A. Low power phase control

B. Low power current control

C. High power phase control

D. High power current control

171. Double edge modulation eliminates certain harmonics when the reference is a__________?
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A. Sine wave

B. Square wave

C. Trapezoidal wave

D. Triangular wave

172. Spread time is defined as the interval during which_____________?
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A. anode voltage drops from 10 % of its initial value to zero

B. anode current rises from 90 % to its final value

C. both (A) and (B)

D. anode current rises from 10 % to 90 % of its final value

173. After proper turn on of thyristor____________?
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A. gate signal should present but can be removed

B. none of the above.

C. gate signal must be removed

D. gate signal is always present

174. In a full wave rectifier, the rectification ratio is approximately equal to____________?
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A. 81%

B. 71%

C. 61%

D. 91%

175. An SCR is made up of silicon because_____________?
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A. silicon has small leakage voltage than germanium

B. silicon has small leakage current than germanium

C. silicon has large leakage voltage than germanium

D. silicon has large leakage current than germanium

176. IGBT stands for___________?
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A. Inductive gate bidirectional transistor

B. Insulated gate bipolar transistor

C. Inductive gate bipolar transistor

D. Insulated gate bidirectional transistor

177. A Triac has three terminals viz ___________?
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A. Drain, source, gate

B. Two main terminal and a gate terminal

C. Cathode, anode, gate

D. None of the above

178. Any electrical signal present in a circuit other than the desired signal is known as______________?
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A. All of these

B. Distortion

C. Noise

D. Interference

179. In a silicon controlled rectifier, the load is connected___________?
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A. Across cathode

B. In series with anode

C. In series with cathode

D. Across anode

180. MOSFET stands for______________?
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A. Metal oxide semiconductor field effect transistor

B. Molybdenum oxide semiconductor field effect transistor

C. Metal oxide semiconductor field effect transmitter

D. Metal oxide silicon field effect transistor