 # MCQ in Industrial Electronics Part 3 | ECE Board Exam

(Last Updated On: August 8, 2018) This is the Multiples Choice Questions Part 3 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 3 of the Series

Choose the letter of the best answer in each questions.

101. Referred to a bidirectional trigger diode.

a. Triac

b. UJT

c. BJT

d. Diac

Solution:

102. Voltage required to turn on any thyristor.

a. Trigger voltage

b. Breakover voltage

c. Barrier voltage

d. Supply voltage

Solution:

103. Also known as a four-layer diode.

a. Diac

b. Shockley diode

c. Zener diode

d. FET

Solution:

104. The thyristor counterpart of the unijunction transistor.

a. UJT

b. PUT

c. SBS

d. SCS

Solution:

105. Minimum current required to keep a thyristor “on”.

a. Holding current

b. Trigger current

c. Supply current

d. Collector current

Solution:

106. A unidirectional-three terminal device, the most popular of thyristors.

a. SCS

b. Triac

c. UJT

d. SCR

Solution:

107. The angle of an AC supply voltage during which an SCR is “off”.

a. Conduction angle

b. Firing delay angle

c. Right angle

d. Off angle

Solution:

108. Thyristors are most often used as

a. Switches

b. Amplifiers

c. Buffers

d. Decoders

Solution:

109. The total internal series resistance of the UJT.

a. Bulk’s resistance

b. Total resistance

c. Interbase resistance

d. RIS

Solution:

110. The most popular and typical breakover voltage of a diac.

a. 32 V

b. 16 V

c. 8 V

d. 4 V

Solution:

111. The peak voltage of a PUT is

a. VD + VBB

b. VG + VBB

c. VD + VG

d. VBB

Solution:

112. A UJT has η = 0.65 and is connected to a 20 V supply. What is its VEB1?

a. 12 V

b. 13.6 V

c. 12.7 V

d. 14 V

Solution:

113. The three terminal semiconductor device that acts in either direction.

a. Triac

b. SCR

c. Diac

d. SCS

Solution:

114. The P of PUT stands for

a. Programmable

b. Performance

c. Peak

d. Post

Solution:

115. The terminals of a UJT are

a. Gate, Anode, Cathode

b. Anode, Cathode

c. Emitter, Base

d. Emitter, Base1, Base2

Solution:

116. The lowest current that can prevent the transition of a UJT from conduction to blocking region.

a. Switching current

b. Emitter current

c. Valley current

d. Peak current

Solution:

117. The SCS has how many gate terminals?

a. 0

b. 1

c. 2

d. 3

Solution:

118. What device has two terminals connected in inverse-parallel that pass in two directions?

a. Triac

b. Diac

c. Shockley

d. SCR

Solution:

119. What is the breakover voltage of a PUT if it is connected to a 15 V supply across the gate terminal?

a. 10.7 V

b. 23.7 V

c. 15.7 V

d. 5.3 V

Solution:

120. The gap between the forward blocking region and the forward conduction region.

a. Band gap

b. Switching region

c. Jump gap

d. Negative resistance region

Solution:

121. The cathode of the PUT is the counterpart of which terminal in UJT?

a. Anode

b. Base2

c. Emitter

d. Base1

Solution:

122. An electronic switch that has the highest single device current capacity and can withstand overloads better.

a. Thyratrons

b. Ignitrons

c. SCR

d. Triac

Solution:

123. Group of devices with 4 or more semiconductor layers.

a. Transistors

b. Diodes

c. Thyristors

d. Op-Amps

Solution:

124. Identify which of the following is a three layer device.

a. SCS

b. Diac

c. Triac

d. PUT

Solution:

125. What device can be modeled by a diode and two resistors?

a. BJT

b. DIAC

c. SCR

d. UJT

Solution:

126. A junction that is formed by adding controlled amounts of an impurity to the melt during crystal growth is termed as

a. Fused junction

b. Unijunction

c. Alloy junction

d. Doped junction

Solution:

127. A triac is a ________.

a. 2 terminal switch

b. 2 terminal bilateral switch

c. 3 terminal unilateral switch

d. 3 terminal bidirectional switch

Solution:

128. A thyristor equivalent of a thyratron tube is ________.

a. Diac

b. Triac

c. SCR

d. PUT

Solution:

129. Which of the following describes a triac?

a. Conducts when not triggered

b. Conducts when not triggered in both directions

c. Conducts when triggered in one direction

d. Conducts when triggered in both direction

Solution:

130. Minimum anode current to hold a thyristor at conduction.

a. Trigger

b. Maintaining current

c. Holding current

d. Threshold voltage

Solution:

131. General term for semiconductor devices primarily used as switches.

a. Shockley

b. Thyratron

c. Thyristor

d. Relay

Solution:

132. A two-terminal, unidirectional thyristor.

a. DIAC

b. Shockley

c. TRIAC

d. Diode

Solution:

133. A thyristor is basically __________.

a. PNPN device

b. A combination of diac and triac

c. A set of SCRs

d. A set of SCR, diac and triac

Solution:

134. What is the PNPN device with two gates?

a. Diac

b. Triac

c. SUS

d. SCS

Solution:

135. Which device incorporates a terminal for synchronizing purposes?

a. Diac

b. Triac

c. SUS

d. SCR

Solution:

136. An SCR is a _________.

a. Unijunction device

b. Device with three junctions

c. Device with four junctions

d. Device with two junctions

Solution:

137. A thyristor can be turned off

a. By reducing the anode current below the holding current value

b. By reversing the anode voltage

c. Either a or b

d. Both a and b

Solution:

138. Minimum duration of pulse triggering system for thyristors is ________.

a. At least 10 microseconds

b. At least 30 milliseconds

c. At least 10 milliseconds

d. At least 1 second

Solution:

139. A device that cannot be triggered by voltage of either polarity is ________.

a. Diac

b. Triac

c. SCS

d. All of the above

Solution:

140. Technically, what is dicing means?

a. Process of joining two diacs

b. Circuit of reducing noise

c. Device for reducing magnetic and radio interference

d. Process of breaking the silicon slice into chips

Solution:

141. The term used to describe the process whereby two transistors with positive feedback are used to simulate the action of the thyristor.

a. Arcing

b. Latching

c. Damping

d. Switching

Solution:

142. It is the minimum anode current to hold a thyristor at conduction.

a. Trigger

b. Maintaining current

c. Holding current

d. Threshold voltage

Solution:

143. Electron tube containing mercury functioning as a rectifier.

a. Thyratron

b. Ignitron

c. Thyrector

d. SCR

Solution:

144. How do you stop the conduction during which the SCR is also conducting?

a. Remove voltage gate

b. Increase cathode voltage

c. Interrupt anode current

d. Reduce gate current

Solution:

145. A series RC connected in parallel with an SCR to eliminate false triggering is the _______.

a. Crowbar

b. Snubber

c. Varistor

d. Eliminator

Solution:

146. Which are the three terminals of a TRIAC?

a. Gate, anode1 and anode2

b. Gate, source and sink

c. Base, emitter and collector

d. Emitter, base1 and base2

Solution:

147. The term used to describe the process whereby two transistors with positive feedback are used to simulate the action of the thyristor.

a. Arcing

b. Latching

c. Damping

d. Switching

Solution:

148. The minimum emitter to base voltage to trigger the UJT is the ________.

a. Forward breakover voltage

b. Trigger

c. Breakdown voltage

d. Peak voltage

Solution:

149. The ratio of the emitter to base1 resistance to the interbase resistance of a UJT is called ________.

a. Aspect ratio

b. Current gain

c. Voltage gain

d. Intrinsic standoff ratio

Solution:

150. For a UJT, it is the region between the peak and valley points as seen in its characteristics curve.

a. Active region

b. Negative resistance region

c. Trigger region

d. Saturation region

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
PART 8: MCQ from Number 351 – 400                 Answer key: included

### Complete List of MCQs in Electronics Engineering per topic

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