MCQ in Power Generators, Sources, Principles, Applications Part 8 | ECE Board Exam

(Last Updated On: May 11, 2018)

MCQ in Power Generators, Sources, Principles, Applications Part 8 | ECE Board Exam

This is the Multiples Choice Questions Part 8 of the Series in Power Generators, Sources, Principles and Applications as one of the Electronics Engineering topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Exam Questions in Electronics Engineering field, Electronics Books, Journals and other Electronics References.

MCQ Topic Outline included in ECE Board Exam Syllabi

  • MCQ in Cells and Batteries
  • MCQ in Electric Generator
  • MCQ in Electronic Power Supply
  • MCQ in Voltage Regulation
  • MCQ in Photovoltaic/Thermoelectric Generator
  • MCQ in Distribution Transformer
  • MCQ in Uninterrupted Power Supply (UPS)
  • MCQ in Float-Battery System
  • MCQ in Converters
  • MCQ in Inverters

Continue Practice Exam Test Questions Part 8 of the Series

351.  Practically how many percent is copper loss to the total loss in transformers?

A.  15%

B.  50%

C.  85%

D.  100%

View Answer:

Answer: Option C

Solution:

352.  What is the purpose of laminating the core of a transformer?

A.  to decrease eddy current loss

B.  to increase eddy current loss

C.  to decrease copper loss

D.  to decrease hysteresis loss

View Answer:

Answer: Option A

Solution:

353.  Large transformers have approximately an efficiency of

A.  25%

B.  45%

C.  75%

D.  95%

View Answer:

Answer: Option D

Solution:

354.  The loss in a transformer due to the changing field is called

A.  leakage

B.  hysteresis loss

C.  eddy loss

D.  keeper

View Answer:

Answer: Option B

Solution:

355.  The ratio of the amount of magnetic flux linking a secondary coil compared to the flux generated by the primary coil:

A.  coupling factor

B.  mutual coupling

C.  coefficient of coupling

D.  hysteresis factor

View Answer:

Answer: Option C

Solution:

356.  Mutual inductance between two coils can be decreased by

A.  moving the coils apart

B.  inserting an iron core

C.  moving the coils close

D.  reducing the reluctance

View Answer:

Answer: Option A

Solution:

357.  An advantage of full-wave rectifier over half-wave rectifier.

A.  Each diode can cool-off during half of each input cycle

B.  The ripple frequency is lower

C.  The tube will conduct during both halves of the input cycle

D.  Output voltage is lower with more ripple

View Answer:

Answer: Option C

Solution:

358.  One of the following items below is not one of the main components of an alternating current power supply.

A.  Power transformer

B.  Voltage regulator

C.  Rectifier

D.  Filter

View Answer:

Answer: Option C

Solution:

359.  Most  electronic  devices/circuits  require  dc-voltage  to  operate.  A  battery  is  a  good power source, however, its operating time is limited. The use of battery also proves to be expensive. A more practical alternative is to use the household main supply, and since  this  is  an  ac-voltage,  it  must  be  converted  to  a  dc-voltage.  The  circuit  that converts this ac-voltage to a dc-voltage is called

A.  rectifier

B.  clamper

C.  filter

D.  regulator

View Answer:

Answer: Option A

Solution:

360.  A rectifier that uses either the positive or negative portion only of the main ac-supply

A.  half-wave

B.  full-wave

C.  full-wave bridge

D.  all of the above

View Answer:

Answer: Option A

Solution:

361.  For a half-wave rectifier, the average output voltage is _______ of the maximum ac voltage.

A.  31.8%

B.  45%

C.  63.6%

D.  90%

View Answer:

Answer: Option A

Solution:

362.  Percent ripple of a half-wave rectifier.

A.  24%

B.  48%

C.  63.6%

D.  121%

View Answer:

Answer: Option D

Solution:

363.  Calculate the dc-voltage at the output of a half-wave rectifier with a 12Vrms input.

A.  2.7 V

B.  3.8 V

C.  4.5 V

D.  5.4 V

View Answer:

Answer: Option D

Solution:

364.  To double the capability of the half-wave rectifier, a __________ must be used.

A.  full-wave rectifier

B.  full-wave bridge

C.  dual-supply

D.  A or B is correct

View Answer:

Answer: Option D

Solution:

365.  Full-wave rectifier defers from full-wave bridge in what aspect?

A.  full-wave uses two diodes, while four for full-wave bridge

B.  diode’s PIV in full-wave is twice that of full-wave bridge

C.  full-wave generates less heat than full-wave bridge

D.  all of the above

View Answer:

Answer: Option D

Solution:

366.  Common to both full-wave and full-wave bridge rectifiers

A.  dc-voltage

B.  ripple factor

C.  ripple frequency and percent ripple

D.  all are correct

View Answer:

Answer: Option D

Solution:

367.  Find direct current voltage from a full-wave rectifier with 120 V peak rectified voltage.

A.  60 V

B.  7.639 V

C.  76.39 V

D.  6.0 V

View Answer:

Answer: Option C

Solution:

368.  The dc-voltage of a full-wave bridge rectifier.

A.  0.318 Vmax

B.  0.45 Vmax

C.  0.636 Vmax

D.  0.90 Vmax

View Answer:

Answer: Option C

Solution:

369.  Relate the magnitude of the dc-output voltage to the ac input rms voltage of a full-wave rectifier.

A.  VDC = 0.318 Vrms

B.  VDC = 0.45 Vrms

C.  VDC = 0.636 Vrms

D.  VDC = 0.90 Vrms

View Answer:

Answer: Option D

Solution:

370.  Determine the dc-voltage of a full-wave bridge rectifier when the input ac-voltage is 24 Vrms.

A.  7.63 V

B.  10.8 V

C.  15.3 V

D.  21.6 V

View Answer:

Answer: Option D

Solution:

371.  Ripple factor of a full-wave rectifier.

A.  0.318

B.  0.48

C.  0.9

D.  1.21

View Answer:

Answer: Option B

Solution:

372.  To improve the dc output voltage of a power supply, a __________.

A.  shunt resistor may be installed

B.  limiting resistor may be installed

C.  feedback element may be installed

D.  filter capacitor may be installed

View Answer:

Answer: Option D

Solution:

373.  Factor(s) that can reduce the ripple voltage of a power supply.

A.  filter capacitance

B.  reduction of load current

C.  increase in input frequency

D.  all of the above

View Answer:

Answer: Option D

Solution:

374.  Making the filter capacitor large in a power supply results to

A.  an increase of the ripple voltage

B.  an increase of the dc-voltage

C.  a decrease of the ripple frequency

D.  A and B above

View Answer:

Answer: Option B

Solution:

375.  Find  the  ripple  factor  (kr)  of  a  sinusoidal  signal  with  peak  ripple  of  4  volts  on  an average of 30.

A.  0.094

B.  0.013

C.  0.130

D.  0.94

View Answer:

Answer: Option A

Solution:

376.  Calculate the peak-to-peak ripple voltage of a 20 V full-wave power supply with a filter capacitor C = 220 µF when delivering a load current of 50 mA.

A.  2.0 Vpp

B.  3.79 Vpp

C.  5.67 Vpp

D.  7.9 Vpp

View Answer:

Answer: Option A

Solution:

377.  In capacitor-filtered power supply, what will happen to the ripple voltage if the load is disconnected?

A.  increases

B.  becomes infinite

C.  becomes unpredictable

D.  drops to zero

View Answer:

Answer: Option D

Solution:

378.  For  a  power  supply  with  a  peak-to-peak  ripple  voltage  of  5  Vpp,  determine  its  rms ripple.

A.  1.44 Vrms

B.  1.77 Vrms

C.  2.88 Vrms

D.  3.54 Vrms

View Answer:

Answer: Option B

Solution:

379.  A 20-Vdc power supply was found to have a ripple voltage of 2 Vrms when supplying 1.5 amps load. Calculate its percent ripple.

A.  7.5 %

B.  10.0 %

C.  12.5 %

D.  15.0 %

View Answer:

Answer: Option B

Solution:

380.  Which power supply filter gives the smallest ripple voltage?

A.  capacitor filter

B.  RC-filter

C.  LC-filter

D.  multi-section LC-filter

View Answer:

Answer: Option D

Solution:

381.  Ripple voltage in power supplies causes unwanted effects on the load it is supplying, i.e. a hum in audio amplifiers. To minimize this effect several filtering techniques are used,  however,  ripple  still  exists.  What  is  a  better  alternative  to  reduce  further  the ripples?

A.  truncation

B.  clipping

C.  clamping

D.  regulation

View Answer:

Answer: Option D

Solution:

382.  A voltage regulator connected in parallel with the load.

A.  series regulator

B.  parallel regulator

C.  shunt regulator

D.  switching regulator

View Answer:

Answer: Option C

Solution:

383.  Which regulator is the most efficient?

A.  series

B.  shunt

C.  switching

D.  modulating

View Answer:

Answer: Option B

Solution:

384.  Voltage reference element in most voltage regulators

A.  diac

B.  thyrector

C.  zener diode

D.  transistor

View Answer:

Answer: Option C

Solution:

385.  In voltage regulators, what do you call the element/device that controls the amount of current/voltage/power?

A.  sampling circuit

B.  comparator

C.  limiter

D.  control element

View Answer:

Answer: Option D

Solution:

386.  The element/device used as a comparator in most voltage regulators.

A.  zener diode

B.  BJT

C.  IGBT

D.  op-amp

View Answer:

Answer: Option D

Solution:

387.  Sampling circuit used in most voltage regulators.

A.  voltage divider network

B.  bleeder network

C.  crowbar

D.  bootstrap circuit

View Answer:

Answer: Option A

Solution:

388.  Most voltage regulators used __________ as their control element.

A.  BJT

B.  SBS

C.  UJT

D.  JFET

View Answer:

Answer: Option A

Solution:

389.  The most efficient voltage regulator and is therefore used in high-current high-voltage applications.

A.  series regulators

B.  shunt regulators

C.  hybrid regulators

D.  switching regulators

View Answer:

Answer: Option D

Solution:

390.  A 12 VDC power supply is regulated using 7805 IC and is used in TTL circuits that require a 0.2 amps current. Determine the dropout voltage of the system.

A.  4 V

B.  5 V

C.  6 V

D.  7 V

View Answer:

Answer: Option D

Solution:

391.  A  load  draws  1  A  current from  a  10-V  regulated  power  supply.  Calculate the  power dissipated by the regulator if it has an input voltage of 16 V.

A.  6 Watts

B.  10 Watts

C.  12 Watts

D.  16 Watts

View Answer:

Answer: Option A

Solution:

392.  Three-terminal fixed positive voltage regulators commonly used in industry.

A.  78XX series

B.  79XX series

C.  723 IC regulator

D.  317 regulator

View Answer:

Answer: Option A

Solution:

393.  What is the regulated output voltage of a 7924 regulator?

A.  + 4 V

B.  – 4 V

C.  + 24 V

D.  – 24 V

View Answer:

Answer: Option D

Solution:

394.  A three-terminal variable positive voltage regulator

A.  317

B.  337

C.  723

D.  741

View Answer:

Answer: Option A

Solution:

395.  What three-terminal IC regulator that has a variable negative voltage output?

A.  317

B.  337

C.  723

D.  741

View Answer:

Answer: Option B

Solution:

396.  In  a  three-terminal  adjustable  positive  voltage  regulator  (317),  what  is  the  band-gap voltage between the output terminal and adjustment terminal?

A.  1.25 V

B.  2.5 V

C.  3.25 V

D.  4.125 V

View Answer:

Answer: Option A

Solution:

397.  Typical ripple rejection of most three-terminal voltage regulators

A.  0.1 %

B.  0.8 %

C.  1.2 %

D.  2.0 %

View Answer:

Answer: Option A

Solution:

398.  The three-terminal voltage regulators, such as the 78XX series has a typical current rating of 1.5 amperes. If a high current is required, say 30 amperes, how will you make modifications from this regulator in order to provide the required current?

A.  by cascading them

B.  by the use of a crowbar circuit

C.  by connecting them in parallel

D.  by the use of external pass transistor

View Answer:

Answer: Option D

Solution:

399.  What is the simplest way of protecting power supplies from reverse-polarity/reverse-current flow?

A.  by a forward-biased diode

B.  by a reverse-biased diode

C.  by a crowbar circuit

D.  by a snubber circuit

View Answer:

Answer: Option B

Solution:

400.  A crowbar circuit is used

A.  to monitor the output current of a power supply and automatically shuts down the system when an overload occur.

B.  to monitor the temperature of a power supply and switches the cooling fan when a threshold temperature is reached.

C.  as voltage reference in regulated power supplies.

D.  as an over-voltage protection in power supplies.

View Answer:

Answer: Option D

Solution:

401.  Technique(s) in using low-power, low-voltage transistors in high voltage regulators.

A.  ground return regulation

B.  by lifting the regulator above ground

C.  connecting them in series

D.  all of the above

View Answer:

Answer: Option D

Solution:

402.  Which of the regulators dissipates less power and therefore generates less heat?

A.  series

B.  shunt

C.  switching

D.  UPS

View Answer:

Answer: Option C

Solution:

403.  In  switching  regulators,  what  are  the  semiconductor  devices  that  can  be  used  as controllable power switches?

A.  BJTs and MDs

B.  MOSFETs and IGBT

C.  GTOs and thyristors

D.  all of the above

View Answer:

Answer: Option D

Solution:

404.  In voltage regulators, the control element plays a major part in providing proper and efficient regulation. What are the desirable characteristics of the control element to be used if excellent regulator is desired?

A.  very small off-state leakage current and high on-state current ratings

B.  large forward and reverse blocking voltage and very small on-sate voltage

C.  short turn-on and turn-off times so that it can be used in high-speed switching regulators

D.  all of the above

View Answer:

Answer: Option D

Solution:

405.  Active devices used in switching regulators may experience large over-currents during conduction  (turn-on-state)  and  large  over-voltages  during  turn-off.  These  excessive currents  and voltages may cause distraction or damage of the active devices. How do we protect them?

A.  by the use of a crowbar circuit

B.  by providing a buck-boost circuit

C.  by shunting a thyrector

D.  by installing a snubber circuit

View Answer:

Answer: Option D

Solution:

406.  One of the major concerns in power electronics is to clean-up or shape-up the utility-supply  voltage  (the  wall-outlet  220  V/60  Hz)  from  disturbances  such  as,  overvolt, undervolt, voltage spikes, and harmonic distortions. What circuit is used for this?

A.  power conditioners

B.  UPS

C.  power inverters

D.  line scanning

View Answer:

Answer: Option A

Solution:

407.  A  power  supply  that  continuously  provides  protection  against  under-voltage, overvoltage and even power outages.

A.  standby power supply

B.  uninterruptible power supply

C.  power conditioners

D.  regulated power supply

View Answer:

Answer: Option B

Solution:

Questions and Answers in Power Generators, Sources, Principles, Applications

Following is the list of practice exam test questions in this brand new series:

MCQ in in Power Generators, Sources, Principles, Applications
PART 1: MCQs from Number 1 – 50                        Answer key: PART 1
PART 2: MCQs from Number 51 – 100                   Answer key: PART 2
PART 3: MCQs from Number 101 – 150                 Answer key: PART 3
PART 4: MCQs from Number 151 – 200                 Answer key: PART 4
PART 5: MCQs from Number 201 – 250                 Answer key: included
PART 6: MCQs from Number 251 – 300                 Answer key: included
PART 7: MCQs from Number 301 – 350                 Answer key: included
PART 8: MCQs from Number 351 – 400                 Answer key: included

Complete List of MCQs in Electronics Engineering per topic

MCQ in Power Generators, Sources, Principles, Applications Part 8 | ECE Board Exam
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