Multiple Choice Questions Topic Outline
- MCQs in Industrial Electronics
- MCQs in Electronic Control System
- MCQs in Industrial Solid State Services
- MCQs in Welding Systems
- MCQs in Thyristors
- MCQs in High Frequency Heating
- MCQs in Feedback Systems / Servomechanism
- MCQs in Transducers
- MCQs in Motor Speed Control Systems
- MCQs in Robotic Principles
- MCQs in Bioelectrical Principles
- MCQs in Instrumentation and Control
The Series
Following is the list of multiple choice questions in this brand new series:
Continue Practice Exam Test Questions Part III of the MCQs 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
102. Voltage required to turn on any thyristor.
- a. Trigger voltage
- b. Breakover voltage
- c. Barrier voltage
- d. Supply voltage
103. Also known as a four-layer diode.
- a. Diac
- b. Shockley diode
- c. Zener diode
- d. FET
104. The thyristor counterpart of the unijunction transistor.
- a. UJT
- b. PUT
- c. SBS
- d. SCS
105. Minimum current required to keep a thyristor “on”.
- a. Holding current
- b. Trigger current
- c. Supply current
- d. Collector current
106. A unidirectional-three terminal device, the most popular of thyristors.
- a. SCS
- b. Triac
- c. UJT
- d. SCR
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
108. Thyristors are most often used as
- a. Switches
- b. Amplifiers
- c. Buffers
- d. Decoders
109. The total internal series resistance of the UJT.
- a. Bulk’s resistance
- b. Total resistance
- c. Interbase resistance
- d. RIS
110. The most popular and typical breakover voltage of a diac.
- a. 32 V
- b. 16 V
- c. 8 V
- d. 4 V
111. The peak voltage of a PUT is
- a. VD + VBB
- b. VG + VBB
- c. VD + VG
- d. VBB
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
113. The three terminal semiconductor device that acts in either direction.
- a. Triac
- b. SCR
- c. Diac
- d. SCS
114. The P of PUT stands for
- a. Programmable
- b. Performance
- c. Peak
- d. Post
115. The terminals of a UJT are
- a. Gate, Anode, Cathode
- b. Anode, Cathode
- c. Emitter, Base
- d. Emitter, Base1, Base2
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
117. The SCS has how many gate terminals?
- a. 0
- b. 1
- c. 2
- d. 3
118. What device has two terminals connected in inverse-parallel that pass in two directions?
- a. Triac
- b. Diac
- c. Shockley
- d. SCR
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
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
121. The cathode of the PUT is the counterpart of which terminal in UJT?
- a. Anode
- b. Base2
- c. Emitter
- d. Base1
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
123. Group of devices with 4 or more semiconductor layers.
- a. Transistors
- b. Diodes
- c. Thyristors
- d. Op-Amps
124. Identify which of the following is a three layer device.
- a. SCS
- b. Diac
- c. Triac
- d. PUT
125. What device can be modeled by a diode and two resistors?
- a. BJT
- b. DIAC
- c. SCR
- d. UJT
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
127. A triac is a ______.
- a. 2 terminal switch
- b. 2 terminal bilateral switch
- c. 3 terminal unilateral switch
- d. 3 terminal bidirectional switch
128. A thyristor equivalent of a thyratron tube is _____.
- a. Diac
- b. Triac
- c. SCR
- d. PUT
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
130. Minimum anode current to hold a thyristor at conduction.
- a. Trigger
- b. Maintaining current
- c. Holding current
- d. Threshold voltage
131. General term for semiconductor devices primarily used as switches.
- a. Shockley
- b. Thyratron
- c. Thyristor
- d. Relay
132. A two-terminal, unidirectional thyristor.
- a. DIAC
- b. Shockley
- c. TRIAC
- d. Diode
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
134. What is the PNPN device with two gates?
- a. Diac
- b. Triac
- c. SUS
- d. SCS
135. Which device incorporates a terminal for synchronizing purposes?
- a. Diac
- b. Triac
- c. SUS
- d. SCR
136. An SCR is a _______.
- a. Unijunction device
- b. Device with three junctions
- c. Device with four junctions
- d. Device with two junctions
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
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
139. A device that cannot be triggered by voltage of either polarity is ________.
- a. Diac
- b. Triac
- c. SCS
- d. All of the above
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
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
142. It is the minimum anode current to hold a thyristor at conduction.
- a. Trigger
- b. Maintaining current
- c. Holding current
- d. Threshold voltage
143. Electron tube containing mercury functioning as a rectifier.
- a. Thyratron
- b. Ignitron
- c. Thyrector
- d. SCR
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
145. A series RC connected in parallel with an SCR to eliminate false triggering is the _______.
- a. Crowbar
- b. Snubber
- c. Varistor
- d. Eliminator
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
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
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
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
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
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