MCQ in Industrial Electronics Part 5 | ECE Board Exam

(Last Updated On: August 8, 2018)

MCQ in Industrial Electronics: Principles and Applications Part 5 | ECE Board Exam

This is the Multiples Choice Questions Part 5 of the Series in Industrial Electronics: 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 Industrial Electronics
  • MCQ in Electronic Control System
  • MCQ in Industrial Solid State Services
  • MCQ in Welding Systems
  • MCQ in Thyristors
  • MCQ in High Frequency Heating
  • MCQ in Feedback Systems / Servomechanism
  • MCQ in Transducers
  • MCQ in Motor Speed Control Systems
  • MCQ in Robotic Principles
  • MCQ in Bioelectrical Principles
  • MCQ in Instrumentation and Control

Continue Practice Exam Test Questions Part 5 of the Series

Choose the letter of the best answer in each questions.

201. For an SCR, dv/dt protection is achieved through the use of:</>

A. RL in series with SCR

B. RC across SCR

C. L in series with SCR

D. RC in series with SCR

View Answer:

Answer: Option B

Solution:

202. A technique use to turn off a thyristor using an external circuit which causes the anode to become negatively biased.

A. force commutation

B. reverse triggering

C. negative feedback

D. doping

View Answer:

Answer: Option A

Solution:

203. The turn-off time of thyristor is 30 m sec at 50°C. Its turn-off time at 100° is

A. same

B. 15 m sec

C. 60 m sec

D. 100 m sec

View Answer:

Answer: Option C

Solution:

204. The peak and valley currents of the PUT are typically ___________ those of a similarly rated UJT.

A. lower than

B. the same as

C. higher than

D. None of the above

View Answer:

Answer: Option A

Solution:

205. What is a solid state equivalent of a gas filled triode?

A. Triac

B. Thyristor

C. SCR

D. SCS

View Answer:

Answer: Option C

Solution:

206. The method(s) for turning off an SCR is (are) categorized as ___________.

A. current interruption

B. forced commutation

C. both current interruption and forced commutation

D. None of the above

View Answer:

Answer: Option C

Solution:

207. In a certain UJT rB1 is 2.5 kΩ and rB2 = 4 kΩ. What is the intrinsic standoff ratio?

A. 0.61538

B. 0.38461

C. 2.6

D. 0.8125

View Answer:

Answer: Option B

Solution:

208. When SCR starts conducting, then __________ losses all control.

A. gate

B. anode

C. cathode

D. anode supply

View Answer:

Answer: Option A

Solution:

209. You have the schematic diagram of several types of circuits. Which of these circuits most likely uses a triac?

A. an oscillator

B. an ac motor control

C. a programmable oscillator

D. an amplifier

View Answer:

Answer: Option B

Solution:

210. Determine RB1 for a silicon PUT if it is determined that h = 0.84, VP = 11.2 V, and RB2 = 5 kΩ.

A. 12.65 kΩ

B. 16.25 kΩ

C. 20.00 kΩ

D. 26.25 kΩ

View Answer:

Answer: Option D

Solution:

211. Which of the following devices does not have a cathode terminal?

A. SCR

B. SCS

C. TRIAC

D. Shockley diode

View Answer:

Answer: Option C

Solution:

212. The UJT operates in what region after peak point?

A. Cut off

B. Negative resistance

C. Saturation

D. Positive resistance

View Answer:

Answer: Option B

Solution:

213. What is basically a two-terminal parallel-inverse combination of semiconductor layers that permits triggering in either direction?

A. DIAC

B. TRIAC

C. QUADRAC

D. Shockley Diode

View Answer:

Answer: Option A

Solution:

214. Which device does not have a gate terminal?

A. Triac

B. SCR

C. FET

D. Diac

View Answer:

Answer: Option D

Solution:

215. The four-layer devices with a control mechanism are commonly referred to as ___________.

A. thyristors

B. transistors

C. diodes

D. None of the above

View Answer:

Answer: Option A

Solution:

216. What is that voltage above when the SCR enters the conduction region?

A. Reverse breakover voltage

B. Forward breakover voltage

C. Holding voltage

D. Trigger voltage

View Answer:

Answer: Option B

Solution:

217. It is a three-terminal silicon diode with the ability to control a large ac power with a small signal.

A. TRIAC

B. SCR

C. UJT

D. SCS

View Answer:

Answer: Option C

Solution:

218. The smallest amount of current that the cathode-anode can have, and still sustain conduction of an SCR is called the:

A. maximum forward current

B. maximum forward gate current

C. holding current

D. reverse gate leakage current

View Answer:

Answer: Option D

Solution:

219. It is the minimum additional current that can make up for any missing input (gate) current in order to keep the device ON.

A. leakage current

B. ac current

C. holding current

D. switching current

View Answer:

Answer: Option D

Solution:

220. The PUT (programmable unijunction transistor) is actually a type of:

A. UJT thyristor

B. FET device

C. TRIAC

D. SCR

View Answer:

Answer: Option A

Solution:

221. What is the typical value of the interbase resistance of UJTs?

A. 20 KΩ

B. Between 4 to 4 KΩ

C. 4 KΩ

D. Between 4 to 10 KΩ

View Answer:

Answer: Option D

Solution:

222. Which of the following is a four-layer diode with an anode gate and a cathode gate?

A. SCS

B. SCR

C. SBS

D. SUS

View Answer:

Answer: Option A

Solution:

223. SCR is a rectifier constructed of silicon material. Silicon is chosen because

A. it is the most abundant material

B. of its strength and ruggedness

C. it is much cheaper than any other material

D. of its high temperature and power capabilities

View Answer:

Answer: Option D

Solution:

224. When the temperature increases, the intrinsic standoff ratio

A. increases

B. decreases

C. essentially constant

D. becomes zero

View Answer:

Answer: Option C

Solution:

225. SCRs have been designed to control powers as high as ___________, with individual ratings as high as ___________ at __________.

A. 1800 MW, 10 A, 2000 V

B. 1800 MW, 2000 A, 10 V

C. 10 MW, 2000 A, 1800 V

D. 2000 MW, 10 A, 1800 V

View Answer:

Answer: Option C

Solution:

226. An SCR is a member of what family?

A. Thyrector

B. Thyratron

C. Thyristor

D. Transistor

View Answer:

Answer: Option C

Solution:

227. Which of the following can change the angle of conduction in SCR?

A. Changing anode voltage

B. Changing gate voltage

C. Reverse biasing the gate

D. Changing cathode voltage

View Answer:

Answer: Option B

Solution:

228. What is the frequency range of application of SCRs?

A. About 10 kHz

B. About 50 kHz

C. About 250 kHz

D. About 1 mHz

View Answer:

Answer: Option B

Solution:

229. The minimum operating voltage of the UJT is typically ____________ that of a similarly rated PUT.

A. lower than

B. the same as

C. higher than

D. None of the above

View Answer:

Answer: Option C

Solution:

230. A UJT is sometimes called a ___________ diode.

A. double-based

B. single-based

C. a rectifier

D. a switching diode

View Answer:

Answer: Option A

Solution:

231. It is like a low current SCR with two gate terminals.

A. UJT

B. PUT

C. SCR

D. SCS

View Answer:

Answer: Option D

Solution:

232. What is the typical value of the reverse resistance of SCRs?

A. 1 Ω to 10 Ω

B. 100 Ω to 1 kΩ

C. 1 kΩ to 50 kΩ

D. 100 kΩ or more

View Answer:

Answer: Option D

Solution:

233. Which of the following is the normal way to turn on a diac?

A. By breakover voltage

B. By gate voltage

C. By gate current

D. By anode current

View Answer:

Answer: Option A

Solution:

234. In a SCR circuit, the angle of conduction can be changed by changing

A. anode voltage

B. anode current

C. forward current rating

D. gate current

View Answer:

Answer: Option D

Solution:

235. The function of snubber circuit connected across the SCR is to:

A. Suppress dv/dt

B. Increase dv/dt

C. Decrease dv/dt

D. Decrease di/dt

View Answer:

Answer: Option A

Solution:

236. An SCR is made of what material?

A. Silicon

B. Carbon

C. Germanium

D. Gallium-arsenide

View Answer:

Answer: Option A

Solution:

237. The SCR can exercise control over ____________ of ac supply.

A. positive or negative half-cycle

B. both positive and negative half-cycles

C. only positive half-cycle

D. only negative half-cycle

View Answer:

Answer: Option A

Solution:

238. Which of the following conditions is necessary for triggering system for thyristors?

A. It should be synchronized with the main supply

B. It must use separate power supply

C. It should provide a train of pulses

D. None of these

View Answer:

Answer: Option A

Solution:

239. A normally operated SCR has an anode which is ___________ with respect to cathode.

A. negative

B. positive

C. at zero potential

D. at infinite potential

View Answer:

Answer: Option B

Solution:

240. Which of the following devices has (have) four layers of semiconductor materials?

A. Silicon-controlled switch (SCS)

B. Gate turn-off switch (GTO)

C. Light-activated silicon-controlled rectifier (LASCR)

D. All of the above

View Answer:

Answer: Option D

Solution:

241. How many pn junction does SCRs have?

A. Two

B. Four

C. Three

D. Five

View Answer:

Answer: Option C

Solution:

242. The silicon-controlled switch (SCS) is similar in construction to the

A. triac.

B. diac.

C. SCR.

D. 4-layer diode.

View Answer:

Answer: Option C

Solution:

243. Which of the following devices has nearly the same turn-on time as turn-off time?

A. SCR

B. GTO

C. SCS

D. LASCR

View Answer:

Answer: Option B

Solution:

244. Which of the following is (are) the advantages of the SCS over a corresponding SCR?

A. Reduced turn-off time

B. Increased control and triggering sensitivity

C. More predictable firing situation

D. All of the above

View Answer:

Answer: Option D

Solution:

245. An effect that reduces the possibility of accidental triggering of the SCS.

A. Miller effect

B. Rate effect

C. End effect

D. Flywheel effect

View Answer:

Answer: Option B

Solution:

246. An SCR whose state is controlled by the light falling upon a silicon semiconductor layer of the device.

A. SCS

B. GTO

C. Thyristor

D. LASCR

View Answer:

Answer: Option D

Solution:

247. Power electronics deals with the control of ac power at what frequencies essentially?

A. 20 KHz

B. 1000 KHz

C. Frequencies less than 10 Hz

D. 60 Hz frequency

View Answer:

Answer: Option D

Solution:

248. To turn on the UJT, the forward bias on emitter diode should be __________ the peak point voltage.

A. more than

B. less than

C. equal to

D. twice

View Answer:

Answer: Option A

Solution:

249. What is the resistance of a certain 4-layer diode in the forward-blocking region if VAK = 15 V and IA = 1 uA

A. 15 Ω

B. 21.21 MΩ

C. 15 M Ω

D. 10.61 MΩ

View Answer:

Answer: Option C

Solution:

250. What is the peak-point voltage for the UJT in problem 76 if VBB = 15 V?

A. 10.605

B. 5.76912

C. 6.46915

D. 0.8125

View Answer:

Answer: Option C

Solution:

Questions and Answers in Industrial Electronics

Following is the list of multiple choice questions in this brand new series:

MCQ in Industrial Electronics Principles and Applications
PART 1: MCQ from Number 1 – 50                        Answer key: PART 1
PART 2: MCQ from Number 51 – 100                   Answer key: PART 2
PART 3: MCQ from Number 101 – 150                 Answer key: PART 3
PART 4: MCQ from Number 151 – 200                 Answer key: PART 4
PART 5: MCQ from Number 201 – 250                 Answer key: PART 5
PART 6: MCQs from Number 251 – 300                 Answer key: PART 6
PART 7: MCQ from Number 301 – 350                 Answer key: included

Complete List of MCQs in Electronics Engineering per topic

MCQ in Industrial Electronics Part 5 | ECE Board Exam
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