MCQ in Power Generators (Cells and Batteries) Part 7 | ECE Board Exam

(Last Updated On: October 22, 2018)

MCQ in Power Generators (Cells and Batteries) Part 7 | ECE Board Exam

This is the Multiples Choice Questions Part 7 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 7 of the Series

Choose the letter of the best answer in each questions.

301. In dc motors, power loss is contributed greatly by

A. flux loss

B. core loss

C. copper loss

D. mechanical friction

View Answer:

Answer: Option C

Solution:

302. Dirt on the commutator may produce

A. isolation

B. excessive sparking

C. power loss

D. lower torque

View Answer:

Answer: Option B

Solution:

303. Motor vibrations are usually caused by

A. loose coupling

B. dirt on the commutator

C. much brush tension

D. worn bearings

View Answer:

Answer: Option D

Solution:

304. When a motor is overloaded, it will usually

A. slow down

B. speed up

C. vibrate

D. overheat

View Answer:

Answer: Option D

Solution:

305. Which motor that produces the highest increase in torque considering the same increase in current?

A. dc shunt

B. dc series

C. differentially compounded

D. cumulatively compounded

View Answer:

Answer: Option B

Solution:

306. When an armature opens in dc motor, it may cause

A. intermittent sparking

B. an increase in speed

C. the motor to slow down

D. the motor to stop rotating

View Answer:

Answer: Option A

Solution:

307. Why do motors take large current during starting?

A. the armature resistance is still low

B. the field produced is still weak

C. it has to break the momentum

D. there’s still a low back emf

View Answer:

Answer: Option D

Solution:

308. In dc motors, the speed will

A. increase with an increase in field strength

B. decrease with an increase in field strength

C. decrease as the supply voltage is increased

D. B and C are correct

View Answer:

Answer: Option B

Solution:

309. When armature current is increased in a dc motor, its armature reaction will

A. also increase

B. decrease

C. increase exponentially

D. decrease exponentially

View Answer:

Answer: Option A

Solution:

310. Why does in dc motor, brushes are positioned such that they will be with the direction of the rotation?

A. to reduce sparking

B. to last long

C. to have less loss

D. all of the above

View Answer:

Answer: Option A

Solution:

311. Motors are used to convert electrical energy to mechanical energy. What type of motor that is best suited for heavy-load application?

A. dc series motors

B. dc compound motors

C. single phase motors

D. polyphase motors

View Answer:

Answer: Option D

Solution:

312. DC shunt motor speed can be controlled electronically by using a _______ in series with the armature winding.

A. thyrector

B. potentiometer

C. rheostat

D. thyristor

View Answer:

Answer: Option D

Solution:

313. Which thyristor is commonly used is motor speed control?

A. triac

B. diac

C. SCR

D. SUS

View Answer:

Answer: Option C

Solution:

314. In controlling motor speed, the SCRs controls the

A. number of pulses

B. phase angle

C. firing angle

D. any of these

View Answer:

Answer: Option C

Solution:

315. How do you reverse the rotation of a dc shunt motor?

A. By reversing the direction of the field current, leaving the armature current the same.

B. By reversing the direction of the armature current, leaving the field current the same.

C. By reversing both field and armature current

D. Either A or B

View Answer:

Answer: Option D

Solution:

316. In motor speed control, what is responsible for SCR firing?

A. trigger circuit

B. threshold circuit

C. reference circuit

D. holding circuit

View Answer:

Answer: Option A

Solution:

317. A circuit that converts ac-voltage to dc-voltage

A. rectifier

B. inverter

C. dc-converter

D. ac-converter

View Answer:

Answer: Option A

Solution:

318. Conversion from dc-voltage to another dc-voltage requires a

A. inverter

B. cycloconverter

C. dc-converter

D. ac-converter

View Answer:

Answer: Option C

Solution:

319. A converter that changes ac-voltage to another ac-voltage level.

A. inverter

B. cycloconverter

C. dc-converter

D. ac-converter

View Answer:

Answer: Option D

Solution:

320. What converter must be used if one wished to change dc-voltage into ac-voltage?

A. inverter

B. cycloconverter

C. dc-converter

D. ac-converter

View Answer:

Answer: Option A

Solution:

321. A converter that changes ac-voltage frequency from one to another.

A. inverter

B. cycloconverter

C. dc-converter

D. ac-converter

View Answer:

Answer: Option B

Solution:

322. In electronic converters, what signal is mostly used to trigger the active device?

A. sine-wave

B. square-wave

C. triangular-wave

D. sawtooth-wave

View Answer:

Answer: Option B

Solution:

323. A transformer consist of the following:

A. An inductance and resistance

B. A parallel resonant circuit

C. A capacitor and an inductor

D. Two coils wound on a common core

View Answer:

Answer: Option D

Solution:

324. Transformer is considered by many as an efficient device due to the fact that

A. it uses an inductive coupling

B. it is magnetically coupled

C. it is a static device

D. it is electrically coupled

View Answer:

Answer: Option C

Solution:

325. With transformer, what is measured when performing open-circuit test?

A. turns ratio

B. copper loss

C. leakage reactance

D. turns impedance

View Answer:

Answer: Option B

Solution:

326. Open-circuit test with transformers is always done on what winding?

A. low-voltage

B. high-voltage

C. primary

D. secondary

View Answer:

Answer: Option A

Solution:

327. Short-circuit test with transformers is always done on what winding?

A. low-voltage

B. high-voltage

C. primary

D. secondary

View Answer:

Answer: Option A

Solution:

328. When the transformer secondary winding is short-circuited, its primary inductance will

A. become zero

B. decrease

C. increase

D. not be affected

View Answer:

Answer: Option C

Solution:

329. Cooling system for transformers with ratings less than 5 kVA

A. forced-air cooling

B. oil-cooling

C. natural air cooling

D. water cooling

View Answer:

Answer: Option C

Solution:

330. For transformers, zero efficiency happens when it has

A. no-load

B. 1/2 of full-load

C. 2/3 of full-load

D. full-load

View Answer:

Answer: Option A

Solution:

331. For transformers, maximum efficiency happens when

A. copper loss is zero

B. copper loss is equal to constant loss

C. the primary and secondary windings are equal

D. the leakage reactances of both windings are equal

View Answer:

Answer: Option B

Solution:

332. In constructing transformers, the primary and secondary windings should have

A. good electrical coupling

B. loose magnetic coupling

C. tight magnetic coupling

D. best inductive coupling

View Answer:

Answer: Option C

Solution:

333. What are the two parameters in transformers that are the same in both primary and secondary?

A. power and voltage

B. power and current

C. power and impedance

D. voltage per turn and ampere-turns

View Answer:

Answer: Option D

Solution:

334. In transformers, the amount of copper used in the primary is

A. less than that of the secondary

B. greater than that of secondary

C. exactly twice that of secondary

D. almost equal as that of secondary

View Answer:

Answer: Option D

Solution:

335. At very low frequencies, transformers woks poorly because

A. its magnetizing current will be very high

B. its core permeability will be greatly increased

C. its core permeability will be greatly reduced

D. its impedance will increase

View Answer:

Answer: Option A

Solution:

336. What will happen if a power transformer is to be operated at a very high frequency?

A. it will have a very high core loss

B. its impedance will decrease

C. its core permeability will be greatly increased

D. its core permeability will be greatly reduced

View Answer:

Answer: Option A

Solution:

337. How are the primary and secondary coupled in autotransformers?

A. electrically

B. magnetically

C. electrically and magnetically

D. capacitively

View Answer:

Answer: Option C

Solution:

338. In a single-phase transformer, the core flux is

A. constant

B. pulsating

C. alternating

D. alternating and sometimes stable

View Answer:

Answer: Option C

Solution:

339. What do you think will happen to a transformer when its primary is connected to a DC supply?

A. It will become more efficient

B. It will become less efficient

C. It will have good regulation

D. It might burn out

View Answer:

Answer: Option D

Solution:

340. Generally, in what application you consider the use of core-type transformers?

A. low voltage and low current

B. low voltage and high current

C. high voltage and low current

D. high voltage and high current

View Answer:

Answer: Option C

Solution:

341. In ________ transformers, when its primary is energized the secondary should never be open-circuited.

A. power

B. voltage

C. current

D. matching

View Answer:

Answer: Option C

Solution:

342. Considered as an ideal transformer

A. the one with no losses and leakage reactance

B. the one with 100% regulation

C. the one with zero efficiency

D. the one with equal primary and secondary

View Answer:

Answer: Option A

Solution:

343. What is the effect of air gaps at the transformer core?

A. Its reluctance is decreased

B. It increases eddy current

C. It decreases hysteresis loss

D. It increases magnetizing current

View Answer:

Answer: Option D

Solution:

344. ________ currents are wasteful currents which flows in cores of transformers and produces heat.

A. Residual

B. Eddy

C. Sneak

D. Magnetizing

View Answer:

Answer: Option B

Solution:

345. What will happen to the eddy current loss in transformers when the load is increased?

A. will also increase

B. will decrease

C. will become infinite

D. nothing will happen

View Answer:

Answer: Option D

Solution:

346. Leakage flux in transformers will cause

A. copper loss to increase

B. copper loss to decrease

C. eddy current to decrease

D. voltage drop in the windings

View Answer:

Answer: Option D

Solution:

347. The increase in temperature in a transformer is mainly due to

A. true power

B. reactive power

C. apparent power

D. virtual power

View Answer:

Answer: Option C

Solution:

348. In transformers, the voltage per turn at the primary is ________ the secondary.

A. less than that of

B. greater than that of

C. a factor of

D. the same as

View Answer:

Answer: Option D

Solution:

349. In transformer windings, the more number of turns

A. the higher is the voltage

B. the lower is the voltage

C. the lower is the impedance

D. the higher is the current

View Answer:

Answer: Option A

Solution:

350. What is true about core-type transformers?

A. It has a shorter magnetic path

B. It has a longer magnetic path

C. It has a very long magnetic path

D. It has an infinite magnetic path

View Answer:

Answer: Option A

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
PART 9: MCQs from Number 401 – 450                 Answer key: included
PART 10: MCQs from Number 451 – 500                 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 (Cells and Batteries) Part 7 | ECE Board Exam
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