Transistors Question & Answers November 29, 2021 By WatElectronics This article lists 100 Transistors MCQs for engineering students. All Transistors Questions & Answers given below include a hint and wherever possible link to the relevant topic. This is helpful for users who are preparing for their exams, interviews, or professionals who would like to brush up their fundamentals on the Transistors topic which is core in Electronics & Electrical Engineering. In most electrical and electronic devices, transistors play a key role. Transistors were developed in 1947 by three American physicists namely Walter Brattain, William Shockley & John Bardeen. So transistors are considered as one of the most essential inventions within science history. Transistors are semiconductor devices that can be used for conducting as well as insulating electric voltage or current. So, they can be used as an amplifier and a switch to control otherwise regulate the electronic signal flow. The NPN and PNP transistors both are bipolar transistors that have two junctions. The emitter and collector of an NPN transistor are made up of N-type semiconductors, and the base is made up of P-type semiconductors whereas the base of PNP transistors is made up of N-type semiconductors. The emitter and collector of a PNP transistor are made up of a P-type semiconductor. When the BJT is used for the amplification of the signal then it can be operated in an active region. In a BJT common emitter configuration, the emitter terminal is common between input and output. In three regions BJT can operate are active, cut-off, and saturation regions. The bipolar junction transistor is categorized into two types they are NPN and PNP transistors. In a bipolar junction transistor, the gain is characterized by the voltage gain, the terminals are not interchangeable and the emitter is heavily doped. 1). The transistors are divided broadly into ….types? 2 3 4 5 None Hint 2). The minority concentration of transistor under open circuit condition is-------? Zero Constant Infinite None of the above. None Hint 3). In the active region the emitter-base junction is --------biased and base-collector junction is---------biased? Reversed biased, Forward biased Forward biased, Forward biased Reversed biased, Reversed biased Forward biased, Reverse biased None Hint 4). Due to forward biasing of emitter-base junction ----------are induced into the base? Minority carriers Majority carriers All the charge carriers Only electrons. None Hint 5). The heavily doped region of the transistor is-----? Emitter Collector Both emitter and collector Only collector None Hint 6). The collector current IC and emitter current IE have---? Same sign in both n-p-n and p-n-p transistors. Opposite sign in both n-p-n and p-n-p transistors. No sign None of the above. None Hint 7). Sign of the emitter current in positive in---? p-n-p transistor. n-p-n transistor. Both a and b Only b None Hint 8). In the active region, collector current depends upon----? Collector voltage. Emitter voltage. Emitter current. None of the above. None Hint 9). The technique used for manufacturing of transistors---? Epitaxial technique. Alloy technique Diffusion technique. All of the above. None Hint 10). When the base region is common to both input and output circuits, the configuration is called-----? Common Emitter. Common Base. Common Collector. Open circuit. None Hint 11). The width of the depletion region -------------with the magnitude of the reverse voltage? Increases Decreases Remains constant None of these None Hint 12). According to Early effect the effective base width changes due to--------? Emitter voltage. Base voltage. Collector voltage. Collector current. None Hint 13). During the punch-through phenomenon, the effective base width is--------? Infinite Steady Zero None of the above. None Hint 14). The voltage level below which the emitter current is very small is called------? Junction voltage. Threshold voltage. Output voltage. All of the above. None Hint 15). In common base configuration, the region where both emitter and collector junctions are forward biased is known as----? Saturation region Active region. Cut-off region. None of the above. None Hint 16). In common-emitter configuration the independent variables are----? Input current and input voltage. Input current and output current. Input current and output voltage. Input voltage and output voltage. None Hint 17). The dependent variables in the common-emitter configuration are---? Input voltage and output current. Input current and output voltage. Input current and output current. Input voltage and output voltage None Hint 18). In common emitter configuration, the input characteristics, when collector shorted to emitter and emitter is forward biased are similar to---? Forward biased diode. Reverse biased diode. Junction diode All of the above. None Hint 19). The reverse collector saturation current ICBO of common emitter configuration----------for every 100C increase in temperature? Decreases Remains the same. Doubles. Goes infinite None Hint 20). The generalized transistor expression, when reverse saturation current ICO and VC are given? Ic= αIE+ICO (1+e^(VC⁄VT )) Ic= -αIE+ICO (1+e^(VC⁄VT )) Ic= -αIE+ICO (1-e^(VC⁄VT )) Ic= -αIE-ICO (1-e^(VC⁄VT )) None Hint 21). When voltage amplification is greater than unity the transistor acts as? Oscillator. Amplifier. Diode Transformer. None Hint 22). In common base configuration, the output voltage is ----? Collector to base voltage VCB Emitter to base voltage VEB Base voltage VB None of the above. None Hint 23). In common base configuration, the input voltage VEB is the function of? Input current and output current. Input current and output voltage. Output current and input voltage None of the above. None Hint 24). The approximate threshold voltage Vγ values for germanium and silicon transistors are….respectively.? 0.1 V, 0.5V 0.5V, 0.1V 0.72V,0.1V 0.72, 0.5V None Hint 25). When input voltage VEB is constant, the increase in collector voltage causes Emitter current to-----? Decrease. Become infinity. zero. Increases None Hint Transistors MCQs for Exams 26). When IE = 0 , the collector current IC =? Reverse saturation current ICO. Base current IB. Zero. Infinite. None Hint 27). For p-n-p transistor Ic and Ico are---? Both Positive. Both Negative. Positive and negative simultaneously. Negative and positive simultaneously. None Hint 28). The large signal current gain α of a common base transistor, when collector current IC= ICO and emitter current IE = 0 are given------ IC/IE (IC-ICO)/(IE-0) -(IC-ICO)/(IE-0) (IC-ICO)/IE None Hint 29). In common emitter configuration, if current gain β is defined as β=α/(1-α) the collector current is given as? IC=(1+β) ICO+βIB IC=(1-β) ICO+βIE IC=(1+β) IEB+βIB IC=(1-β) IEB+βIB None Hint 30). In common collector configuration, the input current is? Base current. Emitter current. Collector current. zero None Hint 31). Transistors are formed by the back-to-back connection of? Two PN junction diodes. Three PN junction diodes. Two p-type regions. Two n-type regions. None Hint 32). Commonly used transistor configuration is? CE configuration. CB configuration. CC configuration. Both b and c. None Hint Please refer to this link to know more about Transistor Configuration 33). Based on the usage in a circuit, transistors are classified into…types? 2 3 4 5 None Hint 34). What is a transistor? Insulator Semiconductor Device Filter Voltage controlled device None Hint 35). A transistor has ….PN junctions? 2 3 4 5 None Hint 36). How many depletion layers are there in a transistor? 2 3 4 5 None Hint 37). The doping of a transistor can be done…..? Lightly Heavily Medium Very low None Hint 38). The large size of the terminal in a transistor is…? Base Emitter Collector CE junction None Hint 39). In PNP, the majority charge carriers are? Electrons Holes Protons Nuetrons None Hint 40). In NPN, the majority charge carriers are? Electrons Neutrons Holes Protons None Hint 41). What is the full form of BJT? Bi-Junction Transistor Base Junction Transistor Bipolar Junction Transistor Blue Junction Transistor None Hint Please refer to this link to know more about Bipolar Junction Transistor 42). The material used to made a transistor is? Silicon Iron Copper Germanium None Hint 43). The purpose of transistor biasing in an amplifier circuit is….? Fix the current amplification value To check the transistor is saturated or not To check the performance of transistor To restrict the flow of current None Hint 44). The transistor’s input impedance is…? Low High Medium Very less None Hint 45). Which of the following is correct in a transistor? IC = IB+IE IB = IC+IE IE = IC+IB IE = IC-IB None Hint 46). The output impedance of a transistor is…..? Low Medium High Very high None Hint 47). If a DC current gain of a NPN transistor (Beta) value is 200 and calculate the IB value necessary for switching a 4mA of switching load? 20 uA 25 uA 30 uA 35 uA None Hint 48). If a NPN transistor has base voltage (Vb) is 10V, Rb is 100 kilo ohms, calculate the base current? 80 uA 90 uA 93 uA 95 uA None Hint 49). Which of the following configuration is used in most of the transistors? CC CE CB None of the above None Hint 50). In which of the following configuration is used highest to connect the transistor’s input impedance? CC CE CB None of the above None Hint Transistors MCQs for Interviews 51). In which of the following is used highest to connect the transistor’s output impedance? CC CE CB None of the above None Hint 52). In a CB configuration, the phase difference among the i/p & o/p voltages is…? 0 degrees 90 degrees 180 degrees 270 degrees None Hint 53). When the transistor’s temperature increases then the resistance at BE terminal…? Increases Decreases Stable Completely reduces None Hint 54). In CC configuration, the value of connected voltage gain is…? 1 < 10 > 10 < 1 None Hint 55). BC147 transistor is made with …material? Cu Si Ge Fe None Hint 56). The signal in a transistor is transferred from …resistance to …? Low to high High to low High to high Low to Low None Hint 57). The function of heat sink in a transistor is…? It enhances the forward current. It decreases the forward current It protects the transistor It prevents increase in extra current. None Hint 58). The operation of transistors in a digital circuit is in …region? Breakdown Active Linear Saturation & Cutoff None Hint 59). When the current ratio IC/IE<1, then it is known as….? Alpha Beta Omega Theta None Hint 60). The function of emitter resistor in a CE configuration is…? Controlling current Stabilization Protection Reduce the temperature None Hint 61). Which of the following transistors are square law devices? BJTs FETs MOSFETs UJTs None Hint 62). The FET provides….? Short circuit in between i/p & o/p High amount of isolation between i/p & o/p Less amount of isolation between i/p & o/p It controls the current flow. None Hint 63). The transistor name is derived from….? Transfer run Ten resistor Transfer resistor Tran resistor None Hint 64). The bandwidth gain of FET with respect to BJT is….? Low Equal High Very low None Hint 65). The collector current in a transistor can be controlled through…? Base current Collector voltage Base resistance Base voltage None Hint 66). If a 3mV signal generates a 3V output, then calculate the voltage gain.? 1000 100 30 3000 None Hint 67). The current ratio of a beta is…? IC/IE IB/IC IE/IB IC/IB None Hint 68). A transistor can be used like a switching device or…? Variable resistor Tuning device Rectifier Fixed resistor None Hint Please refer to this link to know more about Transistor as a Switch 69). If the alpha value is 0.5 then what is the beta value? 2 1 3 4 None Hint 70). Junction transistors are called as…? BJTs FETs MOSFETs JFETs None Hint 71). Which of the following transistors are current controlled devices? FETs MOSFETs JFETs BJTs None Hint 72). BJTs operate in …regions? 2 3 4 5 None Hint 73). Which of the following transistor is a voltage controlled devices? FETs MOSFETs JFETs BJTs None Hint 74). Which of the following transistor is used as a switch, resistor and amplifier? JFET BJT MOSFET FET None Hint 75). Insulated Gate FET is a….? JFET BJT MOSFET FET None Hint Transistors MCQs for Quiz 77). The light sensitive transistors are? Power transistors Photo transistors High frequency Small switching None Hint 78). Field effect transistor includes…terminals? 2 3 4 5 None Hint 79). Which of the following transistor is known as unipolar transistor? FET JFET MOSFET BJT None Hint 80). The input impedance of JFET is…? Low High Medium Very high None Hint Please refer to this link to know more about Junction Field Effect Transistor 81). Thermal stability of BJT is…? High Low Very high Medium None Hint 82). In a CB configuration, IE = 1mA, IC = 0.25mA then what will be the IB value? Transistor Configuration 0.75 0.95 0.65 0.85 None Hint 83). Identify the following transistor…? BJT MOSFET FET JFET None Hint 84). Identify the following transistor's symbol. FET Symbol BJT MOSFET FET JFET None Hint 85). In high frequency applications, which of the following transistor is used? FET BJT MOSFET Heterojunction Bipolar Transistor None Hint 86). Which of the following transistors are used in high speed ICs? FET Ballistic Transistors MOSFET Heterojunction Bipolar Transistor None Hint 87). Which of the following transistors contain metal part of the MOSFET? EOSFET Ballistic Transistors FET Heterojunction Bipolar Transistor None Hint 88). Which transistors work on quantum tunneling principle? EOSFET QFETs FET Heterojunction Bipolar Transistor None Hint 89). ISFET stands for? Ion-sensitive FET Input sensitive FET Input switch FET Impedance sensitive FET None Hint 90). The transistor used in environmental monitoring & biomedicine field is? ISFET MOSFET IGBT JFET None Hint 91). The transistor which uses the quantum tunneling principle is? ISFET TFET IGBT JFET None Hint 92). The double gate transistors are? ISFET TFET IGBT FinFETs None Hint 93). What is the full form of the HEMT? High Energy Mobility Transistor High Electron Mobility Transistor High Electron Metal Transistor High Energy Metal Transistor None Hint 94). Schottky Transistor is also called as? Schottky-barrier Transistor Schottky-Clamped Transistor ISFET JFET None Hint 95). Trench-structure based transistor is? MOSFET UMOS FET ISFET JFET None Hint 96). In which of the transistor, nitrate oxide is used as insulating layer? MOSFET UMOS FET MNOS JFET None Hint 97). Which of the following transistor has fast turn-off capacity? FREDFETs UMOS FET MNOS JFET None Hint 98). Which of the device is used to test a transistor? Multimeter Digital meter Ohmmeter VU meter None Hint 99). In which year, Shockley launched the improved BJT? 1948 1945 1951 1958 None Hint 100). In analog & digital circuits, which of the transistor is used? FET MOSFET JFEET IGBT None Hint Time's up
