Opto-isolator Question & Answers January 3, 2022 By WatElectronics This article lists 100 Opto-isolator MCQs for Engineering Students. All the Opto-isolators Questions & Answers given below includes solution and link wherever possible to the relevant topic. Opto-isolators are integrated electronic components, they are also known as optical isolators, Opto-couplers, and photocouplers. It is used to block high voltages and transfers the data across the isolation barrier by using LEDs and photo-sensitive transistors. It is useful whenever we want to provide electrical isolation between the two circuits, and with the electrical isolation, it is even possible to avoid the ground loops. The PC 817 and 4N25 are very well-known general-purpose optocouplers. The optoisolators consist of light-emitting diodes and light-sensitive devices. The LEDs are made up of gallium arsenide, and the light-sensitive detector detects the light which is emitted from the LED and converts that light signal into electrical signals. The phototransistor, photodarlington transistor, photo Triac, and photo SCR-based optoisolator are the four types of optoisolators and these optoisolators are used in high power choppers, inverters, AC converters, DC converters, light control circuits, dimmer circuits, etc. The isolator is an off-loading device, which means it can operate only when the power supply is in off mode. The single break type isolator, double break type, pantograph, and MCB isolators are types of application-based electrical isolators. 1). The optoisolator consists of _______ devices LEDs Light-sensitive detector Both a and b None of the above None Hint 2). In optoisolators, which of the following device receives the light? LEDs Light sensitive device Both a and b None of the above None Hint 3). The input LEDs on the optoisolators converts the electrical signal into ________ Chemical Mechanical Light None of the above None Hint 4). In PC 817 optoisolator IC the photosensitive element is the ______ Resistor Capacitor Phototransistor Insulator None Hint 5). The optoisolators are categorized into ______ types One Two Four Six None Hint 6). Which one of the following is a photo transistor-based optocoupler? PC816 4N32 4N33 Both b and c None Hint 7). Which one of the following is a photodarlington transistor-based optocoupler? H21B1 4N32 4N33 All of the above None Hint 8). Which one of the following is an example for photo SCR-based optocoupler? H21B1 4N32 4N33 IL420 None Hint 9). The MOC3071 is an example for ______ optocoupler Photo transistor-based Photo Darlington transistor Photo SCR based None of the above None Hint 10). The optocouplers are used in high power _______ Inverters Choppers Both a and b None of the above None Hint 11). Which one of the following optocouplers is designed for triggering TRIACs? PC816 4N32 4N33 Moc3021 None Hint 12). The input current of 6N139 optocoupler is around _____________ mA 0.5mA 1mA 2mA 3mA None Hint 13). Which one of the following is a placement-based electrical isolator? Single break type isolator Bus side isolator Transfer bus side isolator Both b and c None Hint 14). Which one of the following isolators connects directly to the main bus? Bus Transfer bus Lineside None of the above None Hint 15). Which one of the following is a unidirectional device? DIAC TRIAC SCR None of the above None Hint 16). Which one of the following is a controlled device? DIAC TRIAC SCR Both b and c None Hint 17). The firing angle of silicon controlled rectifier is from _____________ 0 to 1800 1800 to 3600 Both a and b None of the above None Hint 18). The pantograph, knee, double break, centre break, etc are the type of ______________ Circuit breakers Isolators Both a and b None of the above None Hint 19). Which one of the following can be used to re-route the power? Circuit breakers Isolators Both a and b None of the above None Hint 20). Which one of the following isolators connects directly to the transfer bus? Bus Transfer bus Lineside None of the above None Hint 21). The frequency range of klystron microwave vacuum tube is ______ 1.4GHz Few GHz to 100 GHz 1GHz 32GHz None Hint 22). The output power of klystron microwave vacuum tube is ______ 10MW 20MW 30MW 40MW None Hint 23). The efficiency of the klystron microwave vacuum tube is less than ______ 90% 10% 60% 70% None Hint 24). In which one of the following tubes does the field travels along with the beam? Klystron Traveling wave tube Both a and b None of the above None Hint 25). The vaccum circuit beaker, SF6 circuit beaker, and oil circuit beaker are some type of ______________ Circuit breakers Isolators Both a and b None of the above None Hint Optoisolator MCQs for Quiz 26). Which one of the following is a part of the relay? Contacts Spring Coil All of the above None Hint 27). What is the standard form of TRIAC? Triode for Alternating Current Triode for Analog Current Triode for Alternating Controller None of the above None Hint 28). Which one of the following have the main contact, moving blades, and has less thermal capabilities? Circuit breaker Isolator Both a and b None of the above None Hint 29).The input current of HCPL-4701 optocoupler is around _____________ mA 0.04mA 1mA 2mA 3mA None Hint 30). Which one of the following is used in choppers, inverters, and rectifiers? DIAC TRIAC SCR Both b and c None Hint 31). What is the standard form of DIAC? Digital Analog Current Diode Analog Current Diode Alternating Current None of the above None Hint 32). Which one of the following has two terminals? DIAC TRIAC Both a and b None of the above None Hint 33). Which one of the following is a bi-directional device? DIAC TRIAC Both a and b None of the above None Hint 34). Which one of the following is an uncontrolled device? DIAC TRIAC Both a and b None of the above None Hint 35). What are the advantages of optocouplers? Works very fast Less noise Low cost, less weight, and compact All of the above None Hint 36). The electrical isolators are categorized into __________________ types Two Four Six Seven None Hint Read more about Isolators 37). Which one of the following is an application-based electrical isolator? Single break type isolator Bus side isolator Transfer bus side isolator None of the above None Hint 38). Which one of the following can't be used to re-route the power? Circuit breakers Isolators Both a and b None of the above None Hint 39). The emitter collector voltage of PC817 IC optocoupler is around _______________ 10V 20V 6V 80V None Hint 40). Which one of the following can operate automatically? Circuit breaker Isolator Both a and b None of the above None Hint 41). Which one of the following has the main contact, arcing contacts, and has better thermal capabilities? Circuit breaker Isolator Both a and b None of the above None Hint 42).The input current of HCNR200 optocoupler is around _____________ mA 0.04mA 1mA 2mA 0.1-10mA None Hint 43). The transistor in a photo transistor is __________________ type of transistor NPN PNP Both a and b None of the above None Hint 44). Which one of the following optocouplers has two transistors? Phototransistor Photo Darlington Photo SCR Photo TRIAC None Hint Read more about Transistors 45). What are the disadvantages of optocouplers? Low cost Works very fast Not handle high current None of the above None Hint 46). Which one of the following has three terminals? DIAC TRIAC Both a and b None of the above None Hint 47). The collector current of the PC817 IC optocoupler is around _______________ 80mW 90mW 70mW 50mW None Hint 48). Which one of the following figures is a photo TRIAC circuit? Figure 1 Figure 2 Figure 3 Figure 4 None Hint 49). Which one of the following is an on-load device? Circuit breaker Isolator Both a and b None of the above None Hint 50). The collector power dissipation of the PC817 IC optocoupler is around _______________ 80mW 90mW 70mW 150mW None Hint Optoisolator MCQs for Interviews 51).The collector emitter voltage of the PC817 IC optocoupler is around _______________ 10V 20V 60V 80V None Hint 52). The power handling capacity is high in _______________ for alternating current Diode Triode Both a and b None of the above None Hint 53). The firing angle of diode for alternating current is ________________ 0 to 180 180 to 360 Both a and b None of the above None Hint 54). Which one of the following was used to trigger TRIAC? DIAC TRIAC Both a and b None of the above None Hint 55).The input current of the 4N49 optocoupler is around _____________ mA 0.04mA 1mA 2mA 0.1-10mA None Hint 56). The insulation thickness of the Broadcom optocoupler is from ________________ 0.08mm to 2mm 0.08mm to 3mm 0.08mm to 4mm 0.08mm to 5mm None Hint 57). Which one of the following is a controlled device? DIAC TRIAC Both a and b None of the above None Hint 58). The power dissipation of the PC817 IC optocoupler is around _______________ 100mW 70mW 80mW 90mW None Hint 59). Which one of the following is an off-load device? Circuit breaker Isolator Both a and b None of the above None Hint 60). The total power dissipation of the PC817 IC optocoupler is around _______________ 80mW 90mW 70mW 200mW None Hint 61). Which one of the following figures is a photo SCR circuit? Figure 1 Figure 2 Figure 3 Figure 4 None Hint 62).The insulation thickness of magnetic optocoupler is up to ________________ for single coil 0.08mm to 2mm 0.02mm 0.08mm to 4mm 0.08mm to 5mm None Hint 63). Which one of the following cannot be used as a circulator? Isolator Circulator Both a and b None of the above None Hint 64).The reverse voltage of the PC817 IC optocoupler is around _______________ 6V 7V 8V 9V None Hint 65). The optocouplers are used in ____________ circuits Light control Dimmer High voltage monitoring All of the above None Hint 66). The TRIAC used in __________________ circuits Control AC power control High power lamp switching All of the above None Hint 67). Which one of the following figures is a symbol for thyristor? Figure (a) Figure (b) Figure (c) None of the above None Hint 68). The application-based electrical isolator is categorized into _______________ Two Three Four Six None Hint 69). What are the applications of DIAC? Used in speed control Used in the heater control Used in TRIAC triggering All of the above None Hint 70).The insulation thickness of capacitive coupler is upto ________________ for single coil 0.08mm to 2mm 0.014mm 0.08mm to 4mm 0.08mm to 5mm None Hint 71). What are the advantages of silicon control rectifiers? HIgh switching speed Small in size Higher efficiency All of the above None Hint 72). The silicon control rectifiers can be used in _________________ circuits Power switching Zero voltage switching Inverters All of the above None Hint 73). Which one of the following devices works even when the avalanche breakdown occurs? TRIAC DIAC Both a and b None of the above None Hint 74). The placement based electrical isolator is categorized into _______________ Three Three Four Six None Hint 75). The firing angle of triode for alternating current is ________________ 0 to 180 180 to 360 Both a and b None of the above None Hint Optoisolator MCQs for Exams 76). The power handling capacity is low in _______________ for alternating current Diode Triode Both a and b None of the above None Hint 77). Which one of the following figures is a photodarlington circuit? Figure 1 Figure 2 Figure 3 Figure 4 None Hint 78).The insulation thickness of the capacitive coupler is up to ________________ for double coil 0.08mm to 2mm 0.014mm 0.08mm to 4mm 0.028mm None Hint 79). The maximum rating of Triac device is ____________ 20KW 30KW 50KW 16KW None Hint 80). How many electrodes do thyristors consist of? One Two Three Four None Hint 81). The power diodes are __________________ layer devices One Two Three Four None Hint 82). Which one of the following is a three-port device? Isolator Circulator Both a and b None of the above None Hint 83).The insulation thickness of the magnetic coupler is up to ________________ for double coil 0.08mm to 2mm 0.04mm 0.08mm to 4mm 0.028mm None Hint 84). Which one of the following figures is a symbol for DIAC? Figure (a) Figure (b) Figure (c) None of the above None Hint 85). Which one of the following is a three-layer device? Power diodes Power transistors Thyristors All of the above None Hint 86). What is the standard form of GTO? Gate Turnoff Thyristor Gate Thyristor Turnon Gate Thyristor Turnoff None of the above None Hint 87). What is the standard form of SITH? Static Induction Transistor Static Induction Thyristor Static Induction Transformer None of the above None Hint 88). What are the pin names of the PC817 IC optocoupler? Anode, cathode, emitter, base Anode, cathode, emitter, collector Anode, cathode, collector, base None of the above None Hint 89). The forward current of the PC817 IC optocoupler is around _______________ 60mA 70mA 80mA 50mA None Hint 90). The figure shown below is a pin diagram of __________________ Zero cross Triac driver SCR output optocoupler Photovoltaic optocoupler None of the above None Hint 91). What is the standard form of MCT? Metal Controlled Switch Mass Controlled Switch Main Controlled Switch MOS Controlled Switch None Hint 92). Which one of the following is a four-layer device? Power diodes Power transistors Thyristors All of the above None Hint 93). Which one of the following figures is a phototransistor circuit? Figure 1 Figure 2 Figure 3 Figure 4 None Hint 94). Which one of the following is a two-port device? Isolator Circulator Both a and b None of the above None Hint 95). Which one of the following figures is a symbol for TRIAC? Figure (a) Figure (b) Figure (c) None of the above None Hint 96).The peak forward current of the PC817 IC optocoupler is around _______________ 6A 7A 1A 5A None Hint 97). What is the standard form of LASCR? Light-Activated Transistor Light-Activated Transformer Light-Activated Thyristor None of the above None Hint 98). The gate firing signals are categorized into __________ One Two Three Four None Hint 99). How many pins does PC817 IC have? Two Three Four Six None Hint 100). What is the standard form of SUS? Static Unilateral Transistor Static Unilateral Switch Silicon Unilateral Switch None of the above None Hint Time's up
