question banksietkece.com/wp-content/uploads/2017/07/bed-qb-2017-2018.doc · web viewsiddharth...

QUESTION BANK 2017

SIDDHARTH GROUP OF INSTITUTIONS :: PUTTUR(AUTONOMOUS)

Siddharth Nagar, Narayanavanam Road – 517583

QUESTION BANK (DESCRIPTIVE)

Subject with Code : Basic Electronic Devices (16EC401) Course & Branch: B.Tech - ECE

Year & Sem: II-B.Tech & I-Sem Regulation: R16

UNIT –IPN JUNCTION DIODE

1. a) Discuss the Energy bands in intrinsic and extrinsic silicon. [L2][CO1][5M] b) Write notes on carrier transport in semiconductor. [L2][CO1][5M]2. a) Explain Drift and Diffusion current for a semiconductor. [L2][CO1][5M] b) With expressions, explain mobility and conductivity of a semiconductor. [L2][CO1][5M]3. a) Describe generation and recombination of carriers. [L1][CO1][5M] b) Derive the expression for Continuity equation for a semiconductor. [L1][CO1][5M]4. a) What is a PN Junction? Explain the formation of depletion layer in a PN junction. [L2][CO1][5M] b) Discuss current components in a PN junction diode. [L2][CO1][5M]5. With neat diagrams, explain the forward and reverse biasing of a PN Junction diode. Draw Its V-I Characteristics. [L2][CO1][10M]6. a) Derive the Diode Current Equation. [L1][CO1][5M] b) Write notes on Diode Resistance. [L2][CO1][5M]7. a) Describe the Temperature Dependence of PN Junction Diode on VI Characteristics. [L1][CO1][7M] b) Determine the value of forward current in the case of a PN junction diode, with Io = 10µA, Vf = 0.8V at T = 3000K. Assume Silicon Diode. [L3][CO1][3M]8. a) How does the reverse saturation current of PN junction diode varies with temperature? Explain. [L2][CO1][5M] b) Find the factor by which the reverse saturation current of a silicon diode will get multiplied when the temperature is increased from 270C to 820C. [L3][CO1][5M]9. a) What is transition capacitance? Derive the expression for transistion capacitance of a

Electronic Circuit Analysis

QUESTION BANK 2017

PN Junction Diode. [L1][CO1][5M] b) Mention the importance of Diffusion capacitance. Derive the expression for Diffusion capacitance of a PN Junction Diode. [L1][CO1][5M]10. a) Draw and explain the energy band diagram of PN Junction Diode. [L2][CO1][5M] b) Calculate the dynamic forward and reverse resistnace of PN Junction silicon diode when the applied voltage is 0.25V at T = 3000K with given Io = 2µA. [L3][CO1][5M]

UNIT –IISPECIAL SEMICONDUCTOR DEVICES

1. a) Compare Zener Breakdown and Avalanche Breakdown in detail. [L4][CO1][5M] b) Discuss the applications of Zener Diode. [L2][CO1][5M]2. a) Draw and explain the VI characteristics of a Zener Diode. [L2][CO1][6M] b) Compare and contrast Zener diode and conventional PN Junction Diode. [L4][CO1][4M]3. a) Draw and explain the basic structure of LED. Mention the applications of LED. [L2][CO1][5M] b) Write notes on Liquid Crystal Display. [L2][CO1][5M]4. a) Describe the characteristics and applications of a photodiode. [L1][CO1][6M] b) What is Varactor Diode? Mention the applications of Varactor Diode. [L1][CO1][4M]5. a) Draw and explain VI characteristics of Tunnel Diode. [L2][CO1][5M] b) Discuss the energy band structure of a Tunnel Diode. [L2][CO1][5M]6. a) Discuss the basic structure and characteristics of TRIAC. [L2][CO1][5M] b) Write notes on DIAC. Mention the applications of DIAC. [L2][CO1][5M]7. a) Draw the basic structure of a SCR and explain its characteristics and applications. [L2][CO1][8M] b) Define Holding Current and Latching Current of SCR. [L1][CO1][2M]


QUESTION BANK 2017

8. a) With neat diagram, describe the working principle and characteristics of UJT. [L1][CO1][6M] b) Write notes on Photo Transistor. [L2][CO1][4M]9. a) Discuss about IR Emitters and mention the applications of IR Emitters. [L2][CO1][5M] b) Explain the construction and applications of Solar Cell. [L2][CO1][5M]10. a) Explain the construction and working principle of Schottky Barrier Diode. [L2][CO1][6M] b) Compare the V – I characteristics of Schottky Barrier Diode with PN Junction Diode. [L4][CO1][4M]

UNIT –IIIRECTIFIERS AND FILTERS

1. a) Draw the circuit diagram of half wave rectifier and explain its operation with the help Of waveforms. [L2][CO1][5M] b) Derive the expressions for Ripple Factor and Efficiency of Half Wave Rectifier. [L1][CO1][5M]2. Derive the expressions for Average DC current, Average DC Voltage, RMS Value of Current, DC Power Output and AC Power Input of a Half Wave Rectifier. [L1][CO1][10M]3. a) Draw the circuit diagram of Full wave rectifier and explain its operation with the help Of waveforms. [L2][CO1][5M] b) Derive the expressions for Ripple Factor and Efficiency of Full Wave Rectifier. [L1][CO1][5M]4. Derive the expressions for Average DC current, Average DC Voltage, RMS Value of Current, DC Power Output and AC Power Input of a Half Wave Rectifier. [L1][CO1][10M]5. A Half wave rectifier has a load of 3.5kΩ. If the diode resistance and the secondary coil Resistance together have resistance of 800Ω and the input voltage of 240V, Calculate (i) Peak, Average and RMS value of the current flowing, (ii) DC power output, (iii) AC Power input and (iv) efficiency of the rectifier. [L1][CO1][10M]6. a) With neat diagram, explain Bridge Rectifier. [L2][CO1][5M] b) A bridge rectifier uses four identical diodes having forward resistance of 5Ω each. Transformer secondary resistance is 5Ω and the secondary voltage of 30V (rms). Determine the DC output voltage for IDC = 200mA and the value of the ripple voltage. [L1][CO1][5M]7. a) Draw the circuit of capacitor filter and explain its operation. [L2][CO1][5M] b) Derive the expression for ripple factor of capacitor filter with HWR and FWR. [L1][CO1][5M]


QUESTION BANK 2017

8. a) Draw the circuit of inductor filter and explain its operation. [L2][CO1][5M] b) Derive the expression for ripple factor of inductor filter. Mention the need of Bleeder resistor. [L1][CO1][5M]9. a) Discuss the L Section Filter with neat diagram. [L2][CO1][4M] b) Derive the Ripple Factor For L Section Filter. [L1][CO1][6M]10. a) Derive the expression for Ripple Factor of CLC Filter. [L1][CO1][6M] b) Compare the different types of filter circuits in terms of ripple factors. [L4][CO1][4M]

UNIT IV

TRANSISTOR CHARACTERISTICS1. a) Discuss the operation of NPN transistor with diagram. [L2][CO2]

[5M]b) With reference to BJT, explain the following terms Emitter Efficiency, Base Transportation Factor and Large signal current gain. [L2][CO2][5M]

2. a) Write the current components of PNP transistor and explain? [L1&L2][CO2][5M]b) If the base current in a transistor is 20µA when the emitter current is 6.4mA, what are the values of α and β? Also calculate the collector current. [L3][CO2][5M]

3. a) A transistor operating in CB configuration has IC = 2.98mA, IE = 3.00 mA and ICO =0.01 mA. What current will flow in the collector circuit for this transistor when connected in CE configuration with a base current of 30μA? [L3][CO2][5M]b) Write notes on early effect of a BJT? [L1][CO2]

[5M]4. a) Describe the phenomena of punch through or reach through in a transistor. [L1][CO2][5M] b) Derive the relation between α, β and ϒ of a Transistor. [L1][CO2][5M]5. a) With a neat diagram, explain how a transistor acts as an amplifier? [L2][CO2][5M] b) Discuss Ebers-Moll Model of BJT. [L2][CO2][5M]6. With neat diagram, explain the Input and Output characteristics of a BJT in CE Configuration. [L2][CO2][10M]7. a) With neat sketches explain the cut off region, active region and saturation region Of a common base transistor output characteristics. [L2][CO2][5M] b) Discuss the Input and Output characteristics of BJT in CC Configuration. [L2][CO2][5M]


QUESTION BANK 2017

8. a) Explain the construction and principle of operation of N-channel JFET. [L2][CO2][5M] b) Define the JFET Volt-Ampere Characteristics and determine FET parameters. [L1][CO2][5M]9. With the help of neat diagram, explain the operation and characteristics of n-channel enhancement type MOSFET. [L2][CO2][10M]10. a) Discuss the operation and drain characteristics of n channel depetion type MOSFET. [L2][CO2][5M] b) Give the comparison between JFET and MOSFET. [L4][CO2][5M]

UNIT- V

TRANSISTOR BIASING AND THERMAL STABILIZATION

1. a) Define Transistor Biasing and explain the need for Biasing? [L1][CO3][5M] b) Explain the concept of DC and AC Load lines and discuss the criteria for fixing the Q-point.

[L2][CO3][5M]2. a) Mention different types of Biasing a Transistor. And explain the Fixed Bias of a Transistor in detail. [L2][CO3][5M] b) Define stability Factor of a Transistor and derive the expression for it. [L1& L3][CO3][5M]3. a) Explain Collector to Base bias of a Transistor with neat circuit diagram [L2][CO3][5M] b) Describe the factors to be considered while designing the biasing circuit which are responsible for shifting the operating point. [L1][CO3][5M]4. Derive the stability factors S, S’ and S’’ of a Transistor Voltage Divider bias . [L3][CO3][10M]5.a) For the circuit shown in the Figure, calculate IB, IC, VCE, VB , VC and VBC. Assume that VBE = 0 and β = 50. [L3][CO3][5M]


QUESTION BANK 2017

b) Mention the advantages and disadvantages of various biasing techniques of BJT. [L2][CO3][5M]6. a) Design a collector to base bias circuit for the specified conditions: Vcc = 15V, VCE = 5V, IC = 5mA and β = 100. [L6][CO3][5M] b) Discuss Diode Compensation Technique for the parameters VBE and ICO. [L2][CO3][5M]7. a) Describe Thermistor and Sensistor Compensation Techniques. [L1][CO3][5M] b) Discuss about Thermal Runaway and Thermal Resistance. [L2][CO3][5M]8. Derive the condition for Thermal Stability to avoid thermal runaway. [L3][CO3][10M]9. a) Derive the expression for Stability Factor S of a Fixed Bias Circuit. [L3][CO3][5M] b) Derive the expression for Stability Factor S of a Collector to Base Bias Circuit. [L3][CO3][5M]10. a) Define the three stability factors of BJT and explain the need of these stability factors In BJT. [L2][CO3][5M] b) With neat diagram, explain Voltage Divider Bias Circuit for JFET. [L2][CO3][5M]

Prepared by: 1. Mr M. Afsar Ali

Professor/ECE2. Ms P.Ratna Kamala

Professor/ECE

SIDDHARTH GROUP OF INSTITUTIONS :: PUTTURSiddharth Nagar, Narayanavanam Road – 517583

QUESTION BANK (OBJECTIVE)

Subject with Code : Basic Electronic Devices (16EC401) Course & Branch: B.Tech - ECE

Year & Sem: II-B.Tech & I-Sem Regulation: R16

UNIT –I

PN JUNCTION DIODE

1. Valence electrons are the [ ]A) loosely packed electrons B) mobile electronsC) electrons present in the outermost orbit D) all the above


QUESTION BANK 2017

2. The element that does not have three valence electrons is [ ]A) boron B) aluminium C) germanium D) gallium3. The element having four valence electrons is [ ]A) silicon B) germanium C) both (a) and (b) D) none of the above4. The forbidden energy gap for silicon is [ ]A) 1.12 eV B) 0.32 eV C) 0.72eV D) 7.2eV5. The forbidden energy gap for germanium is [ ]A) 0.12 eV B)0.32eV C) 0.72eV D) 0.92eV6. The resistivity of a semiconductor [ ]A) increases as the temperature increases B) decreases as the temperature increasesC) remains constant even when temperature varies D) none of the above7. Semiconductor has a [ ]A) zero temperature coefficient of resistance B) positive temperature coefficient of resistanceC) negative temperature coefficient of resistance D) none of the above8. The donor impurity element is [ ]A) aluminium B) boron C) phosphorous D) indium9. The acceptor impurity element is [ ]A) antimony B) gallium C) arsenic D) phosphorous10. The element which does not have five valence electrons is [ ]A) antimony B) arsenic C) gallium D) phosphorous11. The forbidden bandgap of the semiconductor material [ ]A) increases with increase in temperature B) decreases with increase in temperatureC) does not vary with temperature D) none of the above12. One of the following is not a semiconductor [ ]A) Gallium arsenide B) Indium C) Germanium D) Silicon13. Mobility of a charge carrier is given by [ ]A) v/E B) E/v C) Dn D) Dp

14. The static resistnace of a diode is [ ]A) its opposition to the DC current flow B) its opposition to the AC current flowC) resistance of diode when forward biased D) none of the above15. When the reverse bias is applied to a junction diode, it [ ]A) lowers the potential barrier B) raises the potential barrierC) greatly decreases the minority carrier current D) greatly increases the minority carrier current16. Doping of semiconductor is [ ]A) the process of purifying semiconductor materialsB) the process of adding certain impurities to the semiconductor material in controlled amountsC) the process of converting semiconductor material into some form of active device such as FETD) one of the steps used in the fabrication of ICs17. Referring to the energy level diagram of semiconductor materials, the width of forbidden energy gap is about [ ]A) 10eV B) 100eV C) 1eV D) 0.1eV18. A PN junction diode [ ]A) has high resistance in both forward and reverse directionsB) has low resistance in the forward directionC) has high resistance in the forward directionD) has low resistance in the reverse direction19. If a PN junction is not biased, the junction current at equilibrium is [ ] A) zero as no charges cross the junctionB) zero as equal number of carriers cross the barrierC) mainly due to diffusion of majority charge carriers


QUESTION BANK 2017

D) mainly due to top diffusion of majority charge carriers20. In a PN junction, the potential barrier is due to the charges on either side of the junction, Which consists ofA) fixed donor and acceptor ions B) majority carriers onlyC) minority carriers only D) both majority and minority carriers21. In a PN junction, the region containing the uncompressed acceptor and donor ions is called [ ]A) transistion zone B) depletion region C) neutral region D) active region22. In a forward biased PN junction diode, the [ ]A) positive terminal of the battery is connected to the P side and the negative to the N sideB) positive terminal of the battery is connected to the N side and the negative to the P sideC) N side is directly connected to the N sideD) junction is earthed23. When PN junction is forward biased [ ]A) electrons in the N region are injected into the P regionB) holes in the P region are injected into the N regionC) both (a) and (b)D) None of the above24. When we apply reverse bias to a junction diode, it [ ]A) lowers the potential barrier B) raises the potential barrierC) greatly decreases the minority carrier current D) greatly increases the majority carrier current25. Under normal operating voltage, the reverse current in a silicon diode is about [ ]A) 10mA B) 1µA C) 1000 µA D) None of the above26. The depletion region in a PN diode is due toA) reverse biasing B) forward biasingC) an area created by crystal doping D) an area void of current carriers27. When a diode is forward biased, [ ]A) barrier potential increases B) barrier potential decreasesC) majority current decreases D) minority current decreases28. For a Germanium PN junction, the maximum value of barrier potential is [ ]A) 0.3V B) 0.7V C) 1.3V D) 1.7V29. For a Silicon PN junction, the maximum value of barrier potential is [ ]A) 0.3V B) 0.7V C) 1.3V D) 1.7V30. The resistivity of a semiconductor depends on the [ ]A) shape of the semiconductor B) atomic nature of the semiconductorC) majority current decreases D) minority current decreases31. When holes leave the p material to fill electrons in the n material, the process is called [ ]A) mixing B) depletion C) diffusion D) none of the above32. The depletion region in a PN junction is due to [ ]A) reverse biasing B) forward biasingC) diffusion D) none of the above33. Current flow in a semiconductordepends on the phenomenon [ ]A) drift B) diffusion C) recombination D) All of the above34. In a semiconductor diode, V – I relationship is such thatA) current varies linearly with voltage B) current increases exponentially with voltageC) current varies inversely with voltage D) none of these35. The capacitance appearing across a reverse biased semiconductor junction [ ]A) increases with increase in bias voltage B) decreases with increase in bias voltageC) is independent of bias voltage D) none of these36. The PN junction diode is a [ ]A) passive device B) vaccum tube C) unilateral device D) bilateral device


QUESTION BANK 2017

37. A certain amount of diode current still flows when diode is under reverse bias condition. What is this current called? [ ]A) Reverse bias current B) Reverse saturation currentC) Reverse diode Current D) Diode off current38. The number of minority carriers crossing the junction of a PN junction diode depends Primarily on [ ]A) concentration of doping impurities B) magnitude of potential barrierC) magnitude of forward bias voltage D) rate of thermal generation of electron hole pairs39. Reverse saturation current in a germanium diode is of the order of [ ]A) 1nA B) 1µA C) 1mA D) 10mA40. The diffusion capacitance of a forward biased PN junction diode with a steady current I depends On [ ]A) width of the depletion region B) mean lifetime of holesC) mean lifetime of electrons D) junction area

UNIT –II

SPECIAL SEMICONDUCTOR DEVICES1. Zener breakdown occurs [ ]A) due to normally generated carriers B) in lightly doped junctionsC) due to rupture of covalent bonds D) mostly in germanium junctions2. A breakdown which is caused by cumulative multiplication of carriers through field induced Impact ionization occurs in [ ]A) Zener diode B) Tunnel DiodeC) Varactor Diode D) Avalanche Diode3. Zener diode is usually operated [ ]A) in forward bias mode B) in reverse bias modeC) near cut in voltage D) in forward linear region4. For a highly doped diode [ ]A) Zener breakdown is like to take place B) Avalance breakdown is like to take placeC) either (a) or (b) will take place D) neither (a) or (b) will take place5. Which one of the following diode is used for voltage stabilization? [ ]A) PN Junction B) Tunnel C) Varactor D) Zener6. In Zener and Avalanche breakdown diodes, the current flow is due to [ ]A) majority carriers B) minority carriersC) majority and minority carriers D) none of these7. The breakdown that occurs in the reverse biased condition in a narrow junction diode is [ ]A) Zener Breakdown B) Avalanche Breakdown C) both (a) and (b) D) None8. The breakdown that occurs in the reverse biased condition in a wider junction diode is [ ]A) Zener Breakdown B) Avalanche Breakdown C) both (a) and (b) D) None9. A Zener breakdown diode has [ ]A) a positive temperature coefficient B) a negative temperature coefficientC) a breakdown voltage that is independent of temperature D) None of these10. An avalanche breakdown diode has [ ]A) a positive temperature coefficient B) a negative temperature coefficientC) a breakdown voltage that is independent of temperature D) None of these11. In avalanche multiplication, pickup the correct answer [ ]A) Disruption of covalent bond occur by collision B) Direct ruptureC) both (a) and (b) D) None of these12. Which of the following statement is best suited for a Zener diode? [ ]A) It is rectifier diode B) It works in the forward biased region


QUESTION BANK 2017

C) It is a constant voltage device D) It is mostly used in clipping circuit13. There are two semiconductor diodes A and B. One of them is Zener whereas other is Avalanche. Their ratings are 5.6 V and 24V respectively. Then [ ]A) A is Zener, B is Avalanche B) A is avalanche, B is ZenerC) both of them are Zener diodes d) both of them are Avalanche diodes14. The diode used in voltage regulator is [ ]A) PN Junction diode B) Varactor Diode C) Zener Diode D) GUNN Diode15. A tunnel diode [ ]A) is a reverse recovery diode B) has heavy dopingC) is a power diode D) has light doping16. Which one of the following diodes shows the negative resistance region? [ ]A) PN Junction B) Tunnel C) Zener D) Varactor17. The most important application of a Tunnel diode is [ ]A) rectifier B) switching device C) voltage controlled device D) none of these18. The VI characteristics of a Tunnel diode exhibit a [ ]A) multiuvalued unction of voltage B) multivalued function of currentC) single value function of current D) none of these19. The main reason why electrons can tunnel through a PN junction is that [ ]A) they have high energy B) barrier potential is very lowC) depletion layer is extremely thin D) impurity level is low20. The Ip / Iv ratio of tunnel diode is of primary importance in [ ]A) determining tunneling speed of electrons B) the design of an oscillatorC) amplifier designing D) computer applications21. Silicon is preferred for manufacturing Zener diodes because [ ]A) is relatively cheap B) needs lower doping levelC) has high temperature and current capacity D) has lower breakdown voltage22. LEDs are fabricated from [ ]A) silicon B) germanium C) Si or Ge D) gallium arsenide23. An SCR conducts appreciable current when its with respect to cathode [ ]A) anode and gate are both negative B) anode and gate are both positiveC) anode is negative and gate is positive D) gate is negative and anode is positive24. An SCR may be turned OFF by [ ]A) interrupting its anode current B) reversing polarity of its anode cathode voltageC) low current dropout D) all of the above25. The dv/dt effect in an SCR can result in [ ]A) a high rate of rise of anode voltage B) an increased junction capacitanceC) a false triggering D) a low capacitive charging current26. The di/dt effect in an SCR leads to the formation of [ ]A) local hot spots B) conduction zone C) Charge spreading zone D) None of these27. An SCR turns off from conducting state to blocking state on [ ]A) reducing gate current B) reversing gate voltageC) reducing anode current below holding current value D) applying AC to the gate28. When a thyristor is negatively biased [ ]A) all the three junctions are negatively biasedB) outer junctions are positively biased and the inner junction is negatively biasedC) outer junctions are negaively biased and the inner junction is positively biasedD) the junction near the anode is negatively biased and the one near the cathode is positively biased29. The minimum value of current required to maintain conduction in an SCR is called as [ ]A) commutation B) holding C) gate trigger D) breakover30. A photodiode is used in reverse bias because [ ]


QUESTION BANK 2017

A) majority swept are reverse across the junctionB) only one side is illuminatedC) reverse current is small when compared to photocurrentD) reverse current is large when compared to photocurrent31. In photoconductive effect, radiations of wavelength greater than the critical wavelength will [ ]A) produce free electrons B) not produce free electronsC) emit electrons from the surface D) produce electrons32. A Unijunction transistor has [ ]A) anode, cathode and a gate B) two bases and one emitterC) two anodes and one gate D) anode, cathode and two gates33. A UJT has RBB = 10kΩ and RB2 = 4kΩ, its Intrinsic stand off ratio is [ ]A) 0.6 B) 0.4 C) 2.5 D) 5/334. A TRIAC is a [ ]A) 2 terminal switch B) 2 terminal bilateral switchC) 3 terminal unilateral switch D) 3 terminal bidirectional switch35. The TRIAC is equivalent to [ ]A) two SCRs connected in parallel B) two SCRs connected in antiparallelC) one SCR, one diode connected in parallel D) one SCR, one diode connected in antiparallel36. UJT is known as [ ]A) voltage controlled device B) current controlled deviceC) relaxation oscillator D) none of the above37. LCD displays are preferred over LED displays because they [ ]A) are more reliable B) consume less power C) respond quickly D) are cheaper38. Which one of the following statement is correct? A photo diode works on the Principle of [ ]A) photovoltaic effect B) photoconductive effectC) photoelectric effect D) photothermal effect39. A LED is basically which one of the following biased PN Junction? [ ]A) forward biased B) reverse biased C) lightly doped D) heavily doped40. GaAs LEDs emit radiation in the [ ]A) ultraviolet region B) violet blue green range of the visible regionC) visible region D) infra red region

UNIT –IIIRECTIFIERS AND FILTERS

1. A rectifier is used to [ ]A) convert AC voltage to DC Voltage B) convert DC voltage to AC VoltageC) both (a) and (b) D) convert voltage to current2. The ripple factor of a Half Wave Rectifier is [ ]A) 1.21 B) 0.482 C) 0.406 D) 0.1213. The peak inverse voltage of a Half Wave Rectifier is [ ] A) Vm B) 2 Vm C) Vm/2 D) 3Vm

4. The efficiency of a Half Wave Rectifier is [ ]A) 40.6% B) 81.2% C) 1.12% D) 48.2%5. The ripple factor of Full wave rectifier is [ ]A) 1.21 B) 0.482 C) 0.406 D) 0.1216. The peak inverse voltage of a full Wave Rectifier is [ ] A) Vm B) 2 Vm C) Vm/2 D) 3Vm


QUESTION BANK 2017

7. The efficiency of a full Wave Rectifier is [ ]A) 40.6% B) 81.2% C) 1.12% D) 48.2%8. The peak inverse voltage of a Bridge Rectifier is [ ] A) Vm B) 2 Vm C) Vm/2 D) 3Vm

9. The bridge rectifier requires [ ]A) 2 diodes B) 3 diodes C) 4 diodes D) 8 diodes10. In a rectifier, the larger the value of the shunt capacitor filter, the [ ]A) longer time that the current pulse flows through the diodeB) smaller the dc voltage across the loadC) larger the dc voltage across the loadD) larger the peak current in the rectifyinf diode11. The primary function of a rectifier filter is to [ ]A) suppress old harmonics B) remove ripplesC) Stabilize the output dc level D) minimize the input ac variations12. The major advantages of a bridge rectifier is thearA) no center tap transformer is requiredB) the required PIV of each diode is double of that for a FWRC) the required PIV of each diode is half of that for a FWRD) the output is more smooth13. Whichj of the following circuits cannot be operated directly from the mains? [ ]A) Half wave rectifier B) Full Wave RectifierC) Voltage Doubler D) Center Tapped Full Wave Rectifer14. The theoretical maximum efficiency of a Full wave circuit is [ ]A) the same as that os Half wave circuit B) Double as that of a half wave circuitC) definitely more but less than double that of a half wave circuit D) none of these15. In a full wave rectifier, the diodes conduct for [ ]A) one half cycle B) full cycle C) alternate half cycle D) None of these16. The ripple frequency for a full wave rectifier is [ ]A) equal to the supply frequency B) twice the supply frequencyC) thrice the supply frequency D) none of these17. In a Full wave rectifier circuit, the output voltage under load condition is [ ]A) the same as that under no load condition B) less than that under no load conditionC) more than that under no load condition D) none of these18. In a full wave rectifier circuit, the peak inverse coltage per diode is [ ]A) the same as that is a half wave rectifier circuit B) half the value in half wave rectifier circuitC) double the value in half wave rectifier circuit D) none of these19. In a half wave rectifier circuit, the load current flows [ ]A) only for the positive half cycle of the input signalB) for less than half cycle of the input signalC) for more than half cycle of the input signalD) for whole cycle of the input signal20. In a full mwave rectifier circuit, the current in each diode flows for [ ]A) whole cycle of the input signal B) half cycle of the input signalC) more than half cycle of the input signal D) none of these21. In a center tapped FWR, if Vm is the PIV between the center tap and one end of the secondary,The maximum voltage coming across the reverse biased diode is [ ]A) Vm B) 2 Vm C) Vm/2 D) None of these22. In a full wave bridge rectifier, if Vm is the PIV across the secondary of the transformer, themaximum voltage coming across each reverse biased diode is [ ]A) Vm B) 2 Vm C) Vm/2 D) None of these


QUESTION BANK 2017

23. The ripple factor decreases with [ ]A) decrease in C B) increase in CC) increase in frequency D) decrease in frequency24. The diode used in voltage regulator is [ ]A) PN junction diode B) Varactor Diode C) Zener Diode D) GUNN diode25. The ripple factor of a inductor filter is [ ]A) RLw/(√2√3L) B) RL/(√2√3L) C) RL/(3√2wL) D) RL/(2√3wL)26. A bleeder resistor is used in a dc power supply because it [ ]A) keeps the supply OFF B) keeps the supply ONC) improves filtering action D) improves voltage regulation27. The use of a capacitor filter in a rectifier circuit gives satisfactory performance only whenThe load [ ]A) current is high B) current is low C) voltage is high D) voltage is low28. A half wave rectifier is equivalent to [ ]A) a clamper circuit B) a clipper circuitC) a clamper circuit with negative bias D) a clamper circuit with positive bias 29. Bridge rectifiers are preferred because [ ]A) they require small transformer B) they have less peak inverse voltageC) they need small transformer and also have less PIV D) they have low ripple factor30. The basic reason why a full wave rectifier has a twice the efficiency of a half wave rectifierIs that [ ]A) it makes use of transformer B) its ripple factor is much lessC) it utilizes both half cycle of the input D) its output frequency is double the line frequency31. The output of half wave rectifier is suitable only for [ ]A) running car radios B) running ac motorsC) charging batteries D) running tape recorders32. In a LC filter, the ripple factor [ ]A) increases with the load current B) increases with the load resistanceC) remains constant with the load current D) has the lowest value33. If by mistake, ac source in a bridge rectifier, is connected across the dc terminals, it will burnOut and short how many diodes? [ ]A) one B) two C) three D) four34. The dc output polarity from a half wave rectifier can be reversed by reversing [ ]A) the diode B) transformer primary C) transformer secondary D) both (b) and (c)35. In a Half wave rectifier, if a resistance equal to load resistance is connected in parallel withThe diode, then [ ]A) output voltage would be halved B) output voltage would be doubledC) circuit will stop rectifying D) outout voltage will remain unchanged36. If the input supply frequency is 50 Hz, the output ripple frequency of a bridge rectifier is [ ]A) 100 B) 75 C) 50 D) 2537. The DC power output for HWR is [ ]A) (Im

2/π2)RL B) Im/2 C) (Im/2) RL D) Im.RL

38. The TUF for Bridge Rectifier is [ ]A) 0.287 B) 0.693 C) 0.812 D) 0.96339. The amount of ac content in the output can be mathematically expressed by a factor called [ ]A) TUF B) Ripple factor C) PIV D) PRV40. The TUF for HWR is [ ]A) 1.211 B) 0.86 C) 0.287 D) 0.911


QUESTION BANK 2017

UNIT IV

TRANSISTOR CHARACTERISTICS

1. The base of a transistor is ………….. doped. [ ]A) heavily B) moderately C) lightly D) none of the above

2. The element that has the biggest size in a transistor is ……………….. [ ]A) collector B) base C) emitter D) collector-base-junction3. A transistor is a …………… operated device [ ]A) current B) voltage C) both voltage and current D) none of the above4. The emitter of a transistor is ………………… doped [ ]A) lightly B) heavily C) moderately D)none of the above5. The current IB is ………… [ ]A) electron current B) hole current C) donor ion current D) acceptor ion current6. In a transistor ……………….. [ ]A) IC = IE + IB B) IB = IC + IE C) IE = IC – IB D) IE = IC + IB

7. The CE output Collector Current equation, IC = αIE + …………. [ ]A) IB B) ICEO C) ICBO D) βIB

8. The output impedance of a transistor is …………….. [ ]A) high B) zero C) low D) very low9. In a transistor, IC = 100 mA and IE = 100.2 mA. The value of β is …… [ ]A) 100 B) 50 C) about 1 D) 20010. The relation between β and α is ………….. [ ]A) β = 1 / (1 – α ) B) β = (1 – α ) / α C) β = α / (1 – α ) D) β = α / (1 + α )11. The value of β for a transistor is generally ……………….. [ ]A) 1 B) less than 1 C) between 20 and 500 D) above 50012. When transistors are used in digital circuits they usually operate in the [ ]A) active region B) breakdown regionC) saturation and cutoff regions D) linear region 13. The phase difference between the input and output voltages in a CE arrangement is ___ [ ]A) 180o B) 90o C) 270o D) 0o

14. The voltage gain in a transistor connected in ………………. arrangement is the highest [ ]A) common base B) common collector C) common emitter D) none of the above15. The voltage gain of a transistor connected in common collector arrangement is ……….. [ ]A) equal to 1 B) more than 10 C) more than 100 D) less than 116. If the value of α is 0.9, then value of β is ……….. [ ]A) 9 B) 0.9 C) 900 D) 9017. In a transistor, signal is transferred from a …………… circuit [ ]A) high resistance to low resistance B) low resistance to high resistanceC) high resistance to high resistance D) low resistance to low resistance18. The arrow in the symbol of a transistor indicates the direction of …………. [ ]A) electron current in the emitter B) electron current in the collectorC) hole current in the emitter D) donor ion current19. A heat sink is generally used with a transistor to ………… [ ]A) increase the forward current B) decrease the forward currentC) compensate for excessive doping D) prevent excessive temperature rise20. The most commonly used semiconductor in the manufacture of a transistor is …………. [ ]A) germanium B) silicon C) carbon D) none of the above21. JFET is a ____________ controlled device. [ ]A) Voltage B) Current C) Power D) None


QUESTION BANK 2017

22. The relation between FET parameters is [ ]A) μ=gm/rd B) gm = μ * rd C) μ=gm*rd D) rd =gm- μ23. The Gate to source voltage at which the drain current becomes Constant is called [ ]A) Cut-in voltage B) Cut-out voltageC) Threshold voltage D) Pinch-off voltage24. FET that works both in depletion and enhancement mode is [ ]A) P-Ch JFET B) N-ch JFET C) Enhancement MOSFET D) Depletion MOSFET25. When applied input voltage varies the resistance of a channel, the result is called: [ ]A) saturation B) polarization C) cutoff D) field effect26. The transconductance curve of a JFET is a graph of: [ ]A) IS versus VDS B) IC versus VCE C) ID versus VGS D) ID × RDS

27. IDSS can be defined as: [ ]A) the minimum possible drain currentB) the maximum possible current with VGS held at –4 VC) the maximum possible current with VGS held at 0 VD) the maximum drain current with the source shorted28. Which of the following is the fastest switching device? (IES 2014) [ ]A) JFET B) BJT C) MOSFET D) Triode29. FET acts as a VVR in ____________ region. [ ]A) Saturation Region B) Cut-off Region C) Ohmic region D) NONE30. The Drain Characteristics curve of a JFET is a graph of: [ ]A) IS versus VDS B) IC versus VCE C) ID versus VDS D) ID versus VGS

31. The Ebers – Moll model is applicable to [ ] A)Bipolar junction transistors B)nMOS transistorsC)Unipolar Junction transistors D)Junction field effect transistors32. The early effect in a bipolar junction transistor is caused by [ ] A)Fast turn ON B)Fast turn OFF C)Large Collector – Base reverse bias D)Large Emitter – Base forward bias33. When a PNP transistor is properly biased, the holes from the emitter [ ] A) Diffuse through the base into the collector region B) Recombine with the electrons in the base region C) Recombine with the electrons in the emitter region D) Diffuse through the emitter to collector34. When a transistor is connected in common emitter mode it will have [ ] A) Negligible input resistance and high output resistance B) High input resistance and low output resistance C) Medium input resistance and high output resistance D) Low input resistance as well as output resistance35. A BJT is said to be operating in the saturation region, if [ ]A) Both the junctions are reverse biasedB) Base emitter junction is in reverse biased, and base collector junction is forward biasedC) Base emitter junction is in forward biased, and base collector junction is reverse biasedD) Both the junctions are forward biased36. The action of a JFET in its equivalent circuit can best be represented as a [ ]A) Current controlled current source B) Current controlled voltage sourceC) Current controlled inductor D) Voltage controlled inductor 37. Choose the correct match of input resistance of various amplifier configurations shown below: [ ]


QUESTION BANK 2017

38. The impurity commonly used for realizing the base region of a silicon NPN transistor is [ ]A) Gallium B) Indium C) Boron D) Phosphorous39. The leakage current in an NPN transistor is due to the flow of [ ]A) Holes from base to emitter B) Electrons from collector to baseC) Holes from collector to base D)Minority carriers from emitter to collector40. The figure shown represents [ ]

UNIT - VTRANSISTOR BIASING AND THERMAL STABILIZATION

1. Variation in β in a BJT can cause a fixed bias circuit to so [ ] A) Into active mode of operation from saturation mode B) Out of active mode C) Out of saturation D) Into cutoff mode from active mode of operation2. The increase in value of of transistor can cause the fixed bias circuit to [ ]

A)Shift from saturation region to active region B) Shift the operation from active mode to saturation mode C) Shift the operation from saturation mode to cutoff mode D) Shift the operation from cutoff mode to active mode3. Of the four biasing circuits shown in figure, for a BJT, indicate the one which can have maximum bias stability [ ]A) Fixed Bias B) Collector to Base bias C) Emitter Bias D) Self Bias4. Which of the following statements are correct for biasing transistor amplifier configurations [ ] A) CB amplifier has low input impedance and a low current gain B) CC amplifier has low output impedance and a low current gain C) CE amplifier has very poor voltage gain but has very high input impedance D) The current gain of CB amplifier is higher than the current gain of CC amplifier5. In circuit shown, assume that the transistor is in active region. It has a large β and its base emitter

voltage is 0.7 volts. The value of IC is [ ]


QUESTION BANK 2017

A) Indeterminate since RC is not given B) 1 mA C) 5 mA D) 10 mA6. Introducing a resistor in the emitter of a CE amplifier stabilizes the dc operating point against variations in [ ] A) Only the temperature B) Only the β of the transistor C) Both temperature and β D) None of the above7. The Stability factor in a bipolar junction transistor is [ ]

8. Transistor biasing is done to keep ………… in the circuit [ ] A) Proper direct current B) Proper alternating current C) The base current small D) Collector current small9. Operating point represents ………….. [ ] A)Values of IC and VCE when signal is applied B)The magnitude of signal C) Zero signal values of IC and VCE D) none of the above10. If biasing is not done in an amplifier circuit, it results in …………… [ ] A) Decrease in the base current B)Unfaithful amplification C) Excessive collector bias D)None of the above11. Transistor biasing is generally provided by a ……………. [ ] A)Biasing circuit B) Bias battery C) Diode D) None of the above12. For faithful amplification by a transistor circuit, the value of VBE should be ………. for a Silicon transistor [ ] A)Be zero B)Be 0.01 V C)Not fall below 0.7 V D)Be between 0 V and 0.1 V13. For proper operation of the transistor, its collector should have ………… [ ] A)Proper forward bias B) Proper reverse bias C)Very small size D)None of the above14. The circuit that provides best stabilization of operating point is ………… [ ]

A) Base resistor bias B)Collector feedback bias C)Potential divider bias D)None of the above15. The point of intersection of d.c. and a.c. load lines represents ………….. [ ] A) Operating point B) Current gain C)Voltage gain D) None of the above16. An ideal value of stability factor is …………. [ ] A)100 B)200 C)More than 200 d)117. The zero signal IC is generally …… mA in the initial stages of a transistor amplifier [ ]


QUESTION BANK 2017

A) 4 B)1 C)3 D) More than 1018. The disadvantage of base resistor method of transistor biasing is that it ……… [ ] A)Is complicated B)Is sensitive to changes in ß c)Provides high stability d)none19. The biasing circuit has a stability factor of 50. If due to temperature change, ICBO changes by 1

µA, then IC will change by ………… [ ] A)100 µA B)25 µA C)20 µA D)50 µA20. The operating point is also called the …………. [ ] A) Cut off point B) Quiescent point C) Saturation point D) None of the above21. For proper amplification by a transistor circuit, the operating point should be located at the ……. of the d.c. load line [ ] A)The end point B)Middle C)The maximum current point D) None of the above22. The disadvantage of voltage divider bias is that it has …………. [ ] A) High stability factor B) Low base current C) Many resistors D) None of the above23. Thermal runaway occurs when ………. [ ] A) Collector is reverse biased B) Transistor is not biased C) Emitter is forward biased D) Junction capacitance is high24. The purpose of resistance in the emitter circuit of a transistor amplifier is to [ ] A) Limit the maximum emitter current B) Provide base-emitter bias C) Limit the change in emitter current D) None of the above25. The base resistor method is generally used in ……… [ ] A)Amplifier circuits B)Switching circuits C)Rectifier circuits D)None of the above26. The stability factor of a collector feedback bias circuit is ……….. that of base resistor bias. [ ] A)The same as B) More than C)Less than D)None of the above27. If the value of collector current IC increases, then the value of VCE ………… [ ] A) Remains the same B) Decreases C)Increases D) None of the above28. If the temperature increases, the value of VCE ………… [ ] A) Remains the same B) Is increased C)Is decreased D)None of the above29. The stabilization of operating point in potential divider method is provided by [ ] A) RE consideration B) RC consideration C)VCC consideration D) None of the above30. When the temperature changes, the operating point is shifted due to ……. [ ] A) Change in ICBO B) Change in VCC

C) Change in the values of circuit resistance D) None of the above31. The stability factor for Collector to base bias circuit is given by [ ] A) 1+β B) (1+β)/2 C) 1- β D) 1+β2

32. _____________ is a Bias compensation Technique. [ ] A) Fixed Bias B) Collector to Base bias C) Thermistor D) Self Bias33. The condittion to prevent thermal runaway is [ ]

A) B) C) D) None

34. Which of the following has Positive Temperature Coefficient? [ ] A) Thermistor B) Sensistor C) Resistor D) Both A and B35. In Power Transistors, the heat developed at the collector juntion ma be removed by the use of [ ]A) Transistor with high β B) Heat Sink C) Transistor with low β D) None36. The resistance of sensistor increases exponentially with [ ]A) increase of Temperature B) decrease of Temperature C) β D) None37. For normal amplification, The Q-point should be established in [ ] A) Active region B) Saturation region C) Cut-off region D) None38. The condition ensures that the transistor does not undergo thermal run-away is [ ]A) VCE=VCC/2 B) VCE=VCC C) VCE<VCC D) VCE>VCC/2 39. The operating point variation is due to [ ]


QUESTION BANK 2017

A) ICO B) VBE C) β D) All 40. The biasing method which is considered independent of Transistor βdc [ ]A) Fixed biaas B) Collector to bias C) Voltage Divider bias D) Emitter bias


question banksietkece.com/wp-content/uploads/2017/07/bed-qb-2017-2018.doc · web viewsiddharth...

Documents