COMPREHENSIVE VIVA QUESTIONSSubject: EDC 1. List out the common diode applications? 2. Define zener breakdown? 3. Differentiate photodiode and light emitting diode. 4. Explain the forward and reverse bias operation and VI characteristics of a PNJunction diode. 5. a)Derive the diode current equation? . 6. b)Discuss the current components of PN junction diode? 7. a)Explain any two applications of diode with neat diagram . 8. Define pinch - off voltage? 9. Derive the relation between pinch - off voltage & drain current? 10. What is a MOSFET? 11. What is a MESFET? 12. Explain the operation of PNP & NPN transistor? 13. b). What is transistor? State its types 14. Compare CE – CB – CC Configuration? 15. a). Explain the input & output characteristics of CE configuration of a transistor? 16. State FET& its types? 17. a)Explain the input & output Characteristic of CB configuration of a transistor? 18. Explain the construction & characteristics of JFET 19. What is a rectifier? 20. Explain the operation & characteristics of TRIAC? 21. . how a pn-junction can be formed? define avalanche & zener breah down? 22. what are the current components of diode? 23. define intrinsic stand-off ratio? 24. Transistor is called current controlled device?why? 25. Define dirt current? 26. Define Early effect in a Transister 27. Distinguish b/w JFET & MOSFET? 28. What are the advantages & disadvantages of JFET over BJT? 29. What are the advantages of FET? 30. Define peak inverse voltage of a diode? 31. Although zener diode is operated in the reverse break down region, but it doesn’t burn ? why? 32. Explain the operation & characteristics of UJT? 33. Draw the VI characteristics of PN junction diode 34. Write the diode equation 35. Compare n-type and p-type semiconductors. Electronic Devices and Circuits Question Bank UNIT I - PN Diode and Its Applications Part A 1. Define Doping. 2. What do you understand by extrinsic semiconductor? 3. What are the two types of extrinsic semiconductors? 4. What is meant by unbiased PN junction? 5. What is meant by depletion layer in unbiased PN junction? 6. Define forward static and dynamic resistances of diode. 7. Define diffusion capacitance and transition capacitance. 8. Draw the V-I characteristics of PN junction Diode. 9. Write down the expression for Diode Current. 10. Write any two differences between Zener breakdown and Avalanche breakdown. 11. What is meant by Zener diode? 12. Draw the V-I characteristics of Zener diode. 13. List the applications of Zener Diode. 14. Define the ripple factor for a half-wave and full-wave rectifier. 15. Compare the performance of half-wave rectifier and full-wave rectifier. 16. Define Transformer utilization factor. 17. What are the advantages of Bridge rectifier? 18. How shunt regulator is differentiated from series regulator? 19. Draw the block diagram of shunt voltage regulator. 20. Draw the block diagram of series voltage regulator. 21. Compare the rectifier and regulator. 22. What is meant by LED? What materials are used to construct an LED? 23. Define the following for LED a) Radiant intensity b) Irradiance 24. Name the different types of LCDs. 25. State any two applications of LCDs. 26. Write the diffusion current expression and state how this current is formed? 27. Write the temperature dependence of reverse saturation current of PN junction diode. 28. Draw the energy band diagram of a semiconductor. 29. Why an LC filter is called load independent? 30. Draw the equivalent circuit of zener diode under proper biased condition. 31. Why a semiconductor acts as an insulator at ordinary temperature? 32. Define valence band and conductance band. 33. Name some donor and acceptor which can be added as impurities in Silicon and Germanium. 34. Differentiate drift current and diffusion current. 35. Why Silicon is preferred over Germanium in the manufacture of semiconductor devices? 36. Define forbidden energy gap. 37. Define forward and reverse recovery time of a diode. 38. Define knee voltage and breakdown voltage with respect to diode. 39. Define mass action law. 40. Define avalanche breakdown and zener breakdown. 41. Write down the advantages of C filter. 42. Design a full wave rectifier with C filter for Vdc = 12 V; IL = 100 mA and ripple factor = 5%. 43. What is meant by mean life time of a carrier in semiconductor? 44. Define peak inverse voltage of diode. 45. Define load regulation and line regulation. 46. What are the limitations of using zener diode regulator? 47. Define filter. 48. What are the types of filter? 49. A 5V battery is connected across the two diodes connected in series opposing. Find the voltage drop across each diode at room temperature. Part B 1. Explain the operation of forward biased and reverse biased PN junction Diode. 2. (i) Explain the current components in a PN junction diode. (ii) Derive the diode current equation. 3. (i) Briefly explain about avalanche and zener breakdown. (ii)Draw the display of number 1 using seven segment display and explain the theory of liquid crystal cells. 4. Explain the working of Bridge rectifier. Give the expressions for RMS current, PIV, ripple factor and efficiency. 5. Describe the working principle of full wave rectifier and derive the expressions for the ripple factor, efficiency, VDC , IRMS, ILmax and VRMS. 6. Draw the block diagram of series and shunt voltage regulator and explain the operation of series & shunt voltage regulator. 7. Explain the alpha numeric display configuration using LEDs and describe its working. 8. (i)Describe the working of LC filter. (ii)Explain V-I characteristics of Zener diode. 9. (i) Briefly explain the operation of multiple LC filter. (ii) Explain the operation of π section filter with bridge rectifier and also derive an expression for its stability factor. 10. (i) Explain about the switching characteristics of the diode. (ii) Explain about the effect of temperature on diode characteristics. UNIT II: BJT and its Applications Part- A 1. What is transistor? Give its circuit symbol. 2. In a transistor operating in the active region although the collector junction is reverse biased the collector current is quite large. Explain. 3. What is reverse saturation current? 4. Define α and β. 5. What is meant by punch through effect? 6. If the base current in a transistor is 30 micro amps when the emitter current is 2 m A. What are the values of α and β? 7. Give the relation between α and β. 8. Draw the hybrid model for transistor. 9. Define the various h-parameters in a transistor. 10. List some applications of BJT. 11. Define cutoff and active region of a transistor. 12. Draw the output characteristics of a transistor in CE configuration. 13. Draw the small signal low frequency hybrid model of common base configuration. 14. What is optocoupler? 15. Mention two advantages of optocouplers. 16. Why base made thin in BJT? 17. Among CE, CB and CC configurations which is most popular? Why? 18. Define Base Width modulation. 19. What is meant by biasing a transistor? 20. In a common base connection, the emitter current is 1 mA, ICBO = 50 µ A, α = 0.92.Find the total collector current. 21. Describe how amplification and switching achieved by a BJT? 22. What are the bias conditions of base-emitter and base-collector junction to operate a transistor in cut off region? 23. Define the current ICEO. 24. Why is emitter follower so named? 25. What do you understand by h-parameters? 26. What is the significance of h-parameters? 27. Which factors determine the switching speed of the transistor? 28. What are the limitations of switching parameter? 29. What is the need for small signal model of BJT? 30. Differentiate between rise time and storage time? 31. What are the factors that contribute to the delay time when the transistor is used as a switch? 32. Differentiate small signal model with large signal model. 33. Draw the ebers-moll model of CE transistor circuit. Part B 1. Draw and explain the input and output characteristics of a transistor in CE configuration. 2. (i) Explain the operation of Power transistor. (ii) Describe two applications of BJT. 3. Draw and explain the input and output characteristics of a transistor in CB configuration. 4. (i) Explain the working of NPN and PNP transistor. (ii) With neat diagram, describe the principle and working of Optocoupler. 5. With necessary circuit and waveform, explain the switching characteristics of a transistor in detail. 6. (i) Distinguish between the different types of transistor configurations with necessary circuit diagrams. (ii) With neat sketch, explain low frequency and high frequency model of a transistor. 7. Draw and explain the input and output characteristics of a transistor in CC configuration. 8. Derive the expression for AI, AV, Ri and Ro for CB amplifier using h-parameter model. 9. Derive the equations for voltage gain, current gain, input impedance and output admittance for a BJT using low frequency h-parameter model for (a) CE configuration (b) CB configuration and (c) CC configuration. 10. (i)The h-parameters of a transistor are given below. The source and load resistances of a CE amplifier are equal to 2 kΩ.Compute AV, Ri and RO. (ii)If the common-emitter h –parameters of a transistor are given by hie = 2000 Ω ,hfe = 49, hre = 5.5x10-4 and hoe = 2.5x10-5, find the common base h-parameters of the transistor. UNIT III: FET and its Applications Part- A 1. What are the features of JFET? 2. What is meant by Pinch-off voltage? 3. Define amplification factor. 4. Draw the symbol of JFET. 5. Define drain resistance and Transconductance. 6. Write Shockley’s equation. 7. What are the applications of JFET? 8. What are the precautions to be taken when handling MOSFET? 9. What are the differences between BJT and JFET? 10. What are the differences between JFET and MOSFET? 11. Depletion MOSFET is commonly known as “Normally-on” MOSFET. Why? 12. What are the parameters of JFET? 13. Draw the symbol for i) P-channel JFET, iii) N-channel JFET ii) P-channel depletion MOSFET iv) N-channel depletion MOSFET 14. What is Darlington connection? 15. Draw small signal model of Common source amplifier. 16. Define threshold voltage of a MOSFET. 17. Why noise level in FET is smaller than BJT? 18. Why the input impedance in FET is very high in comparison with BJT? 19. Why is FET preferred as a Buffer Amplifier? 20. In a n-channel JFET, IDSS = 20 m A and VP = -6 V. Calculate the drain current when VGS = -3 V. 21. Determine the transconductance of a JFET if its amplification factor is 96 and drain resistance is 32 KΩ. 22. What are the different types of MOSFET? 23. What is the major difference in construction of the D-MOSFET and the E-MOSFET? 24. What are the applications of MOSFET? 25. What is meant by cascade connection? 26. What is meant by cascode connection? 27. State the uses of the MOS diode. 28. Give the relationship between different JFET parameters? 29. Draw the transfer characteristics for JFET and N-Channel MOSFET. Part B 1. Explain with the help of neat diagrams, the structure of an N-channel FET and its Volt-ampere characteristics. In what ways it is different from a bipolar transistor. 2. Describe the construction and explain the operation of depletion mode MOSFET. Also draw the static characteristics. 3. Explain the working of a P channel JFET and draw the V-I characteristics of it. 4. (i)Compare N-with P-channel MOSFETS. (ii)Compare P-channel JFET with N-channel JFET. 5. (i)Compare JFET and MOSFET? (ii)With neat diagram, explain the working of Darlington connection. 6. (i) Draw and explain the small signal model of common drain amplifier. (ii) Draw and explain the small signal model of common gate amplifier. 7. Describe the kind of operation that takes place in the enhancement mode MOSFET. How does this differ from depletion mode type? 8. (i) Draw and explain the small signal model of common source amplifier. (ii) Write short notes on threshold voltage and gate capacitance. 9. (i) Explain the performance of FET as a voltage variable resistor (ii) Define and explain the three parameters of a JFET give the relation between them. 10. (i) Show that if a FET is operated at sufficiently low drain voltage, it behaves as a resistance R given by R = R0 / [1- (VGS / VP)1/2] Where R0 is the channel resistance for zero gate voltage. (ii) Obtain low frequency and high frequency model for FET. UNIT IV: Amplifiers and Oscillators Part- A 1. What is an oscillator? 2. What are sustained oscillations? 3. What is Piezo electric effect? 4. Why quartz crystal is commonly used in crystal oscillator? 5. Why is an RC phase shift oscillator called so? 6. Name three high frequency oscillators. 7. Distinguish between LC and RC oscillator. 8. What are the different feedback topologies? 9. What are the effects of negative feedback? 10. Name two low frequency oscillators. 11. What are the advantages of crystal oscillator? 12. Which oscillator uses both positive and negative feedback? 13. What are the different types of feedback depending in the type of feedback signal? 14. Define Barkhausen criterion. 15. Distinguish between series and shunt feedback. 16. Define desensitivity factor. 17. Why is negative feedback employed in high gain amplifiers? 18. What is feedback amplifier? 19. How does a oscillator differ from an amplifier? 20. Mention the expression for frequency of oscillation for a hartley oscillator. 21. Mention two reasons why LC oscillator is preferred over RC oscillator at radio frequency. 22. What is sustained oscillation? 23. What are the essential parts of an oscillator? 24. Define CMRR. 25. What is differential amplifier? 26. Determine the voltage gain of the negative feedback amplifier whose open loop gain is -150 and 7% of the output is feedback. 27. What are the factors needed to choose type of oscillators? Part B 1. Draw the circuit diagram of a current series feedback amplifier and derive expressions for voltage gain with and without feedback. 2. With a neat sketch explain the working of an RC phase shift oscillator and derive an expression for frequency of oscillation for an RC phase shift oscillator. 3. Explain the working of Colpitt’s oscillator and derive an expression for frequency of oscillation for Colpitt’s oscillator. 4. (i)Write short notes on LC oscillator. (ii)Write short notes on crystal oscillator. 5. Briefly analyse the performance measures of negative feedback amplifiers. 6. Explain in detail about the different feedback topologies. 7. Draw the circuit diagram of a voltage series feedback amplifier and derive expressions for voltage gain with and without feedback. 8. Briefly explain about differential amplifiers. 9. (i) Write notes on frequency stability of an oscillator. (ii) A negative feedback of β = 0.01 is applied to an amplifier of gain 500. Calculate the change in overall gain of the feedback amplifier if the internal amplifier is subjected to a gain reduction of 10 %. 10. (i) (a)An amplifier has a voltage gain of 50 dB with an negative feedback and with a feedback ratio of 1 / 10.Calculate the gain with feedback. (b)The voltage gain of an amplifier without feedback is 50 dB. If it is reduced to 30 dB with feedback, calculate the feedback factor. (ii) Write notes on Wien bridge oscillator. UNIT V: Pulse Circuits Part- A 1. Give the definition for Clipper. 2. What are the applications of Clippers? 3. What is Clamper? 4. What is Astable multivibrator? 5. How a Schmitt trigger is different from a multivibrator? 6. What is a blocking oscillator? 7. What are the applications of Schmitt trigger? 8. What are the applications of Multivibrator? 9. What is Monostable multivibrator? 10. What is Bistable multivibrator? 11. What do you meant by the term “Wave shaping”? 12. What is the difference between positive and negative clippers? 13. Draw neatly the circuit diagram of a voltage quadrupler. 14. What are the applications of clamping circuits? 15. Draw a practical Clamper circuit. Part B 1. With the help of circuit diagram, describe the operation of a clipper that can clip at two independent levels. 2. With a neat sketch, explain the working of an astable multivibrator. 3. With a neat sketch, explain the working of an Bistable multivibrator. 4. Explain the difference between the three types of multivibrators. 5. Draw the circuit diagram of Schmitt trigger circuit and explain its operation with waveforms. 6. Explain the working of UJT based saw tooth oscillators. 7. With a neat sketch, explain the working of an Monostable multivibrator. 8. What do you understand by clamping circuits? Discuss with the help of waveforms, the operation of a clamping circuit to clamp a sine wave input positively at 0 V. 9. (i)Enumerate the conditions under which an RC circuit behaves as an integrator. (ii)Discuss the necessary criteria for a good differentiating circuit. Give some applications of this circuit. 10. Explain about the triggering methods for Bistable multivibrator. 1. Define Clipper. What are its type. 2. What is clamper (with fig) and its applications. 3. What is astable Multivibrator (with fig) 4. What are the applications of multivibrator. 5. What are the applications of Schmitt trigger. 6. What is Bistable multivirator (with fig) ? 7. What do you mean by Wave shapping? 8. Differentiate +ve and -ve Clippers. 9. Define Intransic stand off Ratio. 10. Define Hysterests Voltage in Schmitt Trigger. 11. Give application of UJT. 12. Draw the circuit diagram for ULT Relaxation oscillator and its waveform. 13. Compare Mutivibrator and Oscillator. 14. Compare Astable,Monostable & Bistable Mutivibrator. 15. Compare Astable Multivibrator and Schmitt trigger. 16. Define UTP and LTP. 17. Define Multivibrator. 18. Determine the Equation for frequency for bistable multivibrator. 19. What is bistable multibrator (with fig). 20. Define Clapper. 21. Give application of clippers and clampers. 22. Define Symmetrical Clipper. 23. Define Biased Clipper. Electronic Device and Circuits - Unit 4 - Important 2Mark Questions 1. Define Barkhausen Criteria 2. What is Differential Amplifier? 3. Define CMRR. 4. What are the features of Differential Amplifier? 5. What are advantage of Differential Amplifier ? 6. What is FeedBack amplifier ? 7. What are the Different FeedBack Toplogies ? 8. Give the advantages of Negative feedback amplifier. 9. What is an Oscillator ? 10. Distinguish between LC and RC Oscillator. 11. Give the application of oscillator. 12. What are the advantage and disadvantage of Crystal Oscillator. 13. Give the advantage and Disadvantage of RC Phase Shift Oscillator. 14. Give the advantage and Disadvantage of Colpitts Oscillator. 15. Distinguish Crystal OSC and LC Oscillator. 16. Give the classification of Oscillation. 17. Define FeedBack Factor. 18. Draw Colpitts Oscillator. 19. Compare Voltage Series,Voltage Shunt,Current Series and Current Shunt Feedback. 20. Define Input and Output Resistance of Diff Amplifier. 21. Define Input Bias Current and offset current of Diff Amp. 22. Draw the circuit for RC phase shift Oscillator. 23. State the frequency for RC phase shift oscillator. Electronic Device and Circuits - More Important Questions These are the List of the Question that are repeatedly asked in Anna University Examination. 1. Explain the construction,operation and characteristics of PN Junction Diode. 2. Explain the working principle of half wave / full wave rectifier and derive the expression for ripple factor,efficiency,Vdc,Irms,Idc,Vrms and TUF. 3. Explain the alpha numberic display config using LEDs and describe its working. 4. Explain construction and working of LCD. 5. Draw and Explain the input and output characteristics of a transistor in CE/CB/CC configuration. 6. Explain the Switching Characteristics of transistor. 7. Explain the operation of power transistor. 8. Explain the operation of optocoupler. 9. Construction , Operation and Characteristics of JFET. 10. Construction , Operation and Characteristics of MOSFET. 11. Explain the working of Darlington connection. 12. Explain the performance of FET as VVR. 13. Explain Differential Amplifier. 14. Working of colpits oscillator and derive frequency. 15. Explain feedback topologies(VT series,VT shunt,CT series,CT shunt) 16. Explain schmitt trigger 17. Explain UJT based Sawtooth oscillator. 18. Explain working of Astable and Bistable multivibrator. FET and its Application (Unit 3) - Question Bank Part A 1. Why is FET is known as unipolar device ? 2. Distinguish FET and BJT 3. Distinguish JFET and MOSFET 4. What is meant by pinch off voltage and amplification factor 5. What are the features of JFET 6. Define drain resistance of transconductance 7. What are the applications of JFET? 8. Write the Shockleys equation 9. What are the parameters of JFET. 10. Give small signal model of JEFT 11. Draw the drain characteristics of JFET & mark the regions of operation. 12. Give the drain current Equation of JFET. 13. Define cut off voltage. 14. Distinguish ohmic region & saturation region. 15. Draw transfer char of JFET. 16. Compare the common source, common drain & common gate amplifiers. 17. Draw the circuit diagram of Source Follower 18. Compare DMOSFET & EMOSFET. 19. Give classification of FET. 20. Why do depletion regions do not touch of pinch off? 21. Depletion MOSFET is called normally ON MOSFET. Why? 22. Draw the char of n-channel Enhancement MOSFET. 23. Give the symbol of n&p channel FET,MOSFET. 24. Give the application of EMOSFET & DMOSFET. 25. Justify : JFET is a VVR 26. What is breakdown ? Why does it take place in JFET? What are its effects? 27. What is darlington connection? 28. Define threshold voltage of MOSFET. 29. Why is FET preferred as Buffer Amplifier. 30. What is meant by cascade & cascade connection. Part B 1. Explain with the help of neat diagram construction, working & VI characteristics of n channel JFET. 2. Explain performance of FET as VVR. 3. With neat diagram explain working of Darlington connection. 4. Describe the construction & operation of depletion mode MOSFET & draw its characteristics. 5. Draw & explain small signal model of common source , common Gate & common Drain amplifier. 6. Describe the construction & operation of Enhancement MOSFET & draw its characteristics. 1. Give the value of Charge, Mass of an electron. 2. Define Electron volts. 3. What is atomic number? 4. What are valence electrons? 5. What is forbidden energy gap? 6. What are conductors? Give examples? 7. What are insulators? Give examples? 8. Give the energy band structure of conductor. 9. What are Semiconductors? Give examples? 10. What are the types of Semiconductor? 11. What is Intrinsic Semiconductor? 12. What is Extrinsic Semiconductor? 13. What are the types of Extrinsic Semiconductor? 14. What is P-type Semiconductor? 15. What is N-type Semiconductor? 16. What is doping? 17. Which charge carriers is majority and minority carrier in N-type Semiconductor? 18. Which charge carriers is majority and minority carrier in P-type Semiconductor? 19. Define drift current? 20. Define mean life time of a hole or and electron. 21. What is the other name of continuity equation? What does it indicate? 22. What is depletion region in PN junction? 23. Give the other names of depletion region? 24. What is barrier potential? 25. What is meant by biasing a PN junction? 26. What are the types of biasing a PN junction? 27. What is forward bias and reverse bias in a PN junction? 28. What is meant by reverse recovery time? 29. What are break down diodes? 30. What is break down? What are its types? 31. What is zener breakdown? 32. What is avalanche break down? 33. What is a tunnel diode? 34. What is tunneling phenomenon? 35. What is a schottky diode? 36. Why do we choose q point at the center of the load line? 37. List out the different types of biasing. 38. What do you meant by thermal runway? 39. Why transistor called a current controlled device? 40. 40 .Define current amplification factor? 41. What are the requirements for biasing circuits? 42. When does a transistor act as a switch? 43. What is biasing? 44. What is operating point? 45. What is stability factor? 46. What is d.c load line? 47. What is a.c load line? Machines 1. Mention the types of electrical machines. 2. State Ohm’s law for magnetic circuit. 3. Define leakage flux 4. Define magnetic reluctance 5. State stacking factor. 6. Mention some magnetic materials 7. What is magnetostriction? 8. Define statically induced emf. 9. Define dynamically induced emf. 10. State Fleming’s right hand rule. 11. State Fleming’s Left hand rule. 12. What are the losses called as core loss? 13. Define coercivity. 14. What are factors on which hysteresis loss? 15. What is core loss? What is its significance in electric machines? 16. What is eddy current loss? 17. How hysteresis and eddy current losses are minimized? TRANSFORMERS ________________________________________ PART-A 1. Mention the difference between core and shell type transformers? 2. What is the purpose of laminating the core in a transformer? 3. Does transformer draw any current when secondary is open? Why? 4. Define voltage regulation of a transformer? 5. Define all day efficiency of a transformer? 6. Why transformers are rated in KVA? 7. What are the typical uses of auto transformer? 8. What are the applications of step-up & step-down transformer? 9. How transformers are classified according to their construction? 10. Explain on the material used for core construction? 11. How does change in frequency affect the operation of a given transformer? 12. What is the angle by which no load current will lag the ideal applied voltage? 13. List the arrangement of stepped core arrangement in a transformer? 14. What is the function of transformer oil in a transformer? 15. Can the voltage regulation go negative if so under what condition? 16. Distinguish power transformers & distribution transformers? 17. What is the purpose of providing Taps in transformer and where these are provided? 18. What are the typical uses of auto transformer? 19. How does change in frequency affect the operation of a given transformer? 20. Why are breathers used in transformers? 21. What is the function of transformer oil in a transformer? 1. Define the term pole pitch 2. Define pitch factor 3. Define the term breadth factor 4. Write down the advantages of short pitched coil. 5. What is distributed winding? 6. Explain the following terms with respect to rotating electrical machines. 7. Write the expressions for the synchronous speed. 8. Write the mmf equation of dc machine. 9. What is meant by electromagnetic torque? 10. State the torque equation for round rotor machine. 11. Define rotating magnetic field. DC MACHINES ________________________________________ PART – A 1. What is prime mover? 2. Give the materials used in machine manufacturing 3. How will you change the direction of rotation of a d.c motor? 4. What is back emf in d.c motors? 5. Under what condition the mechanical power developed in a dc motor will be maximum?. 6. What is the function of a no-voltage release coil provided in a dc motor starter? 7. Name the two types of automatic starters used for dc motors. 8. Enumerate the factors on which the speed of a dc motor depends. 9. List the different methods of speed control employed for dc series motor 10. Name the different methods of electrical breaking of dc motors. 11. Under what circumstances does a dc shunt generator fail to build up? 12. To what polarity the interpoles excited in dc motors? 13. What is back emf in d.c motors? 14. Name any four applications of DC series motor. 15. Why DC motors are not operated to develop maximum power in practice? 16. Name the starters used for series motors. 17. Name Different types of starters. 18. Name the Protective devices in a starter. 20. What are the modification in ward Leonard linger system? 21. What type of DC motors are suitable for various torque operations? 22. Define speed regulation. 23. What are the performance curves? 24. To what polarity are the interpoles excited in dc generators? 25. Why are carbon brushes preferred for dc machines? 26. What are the various types of commutation? 27. Name the two methods of improving commutation. 28. What is reactance emf in dc machine? 29. Define the term commutation in dc machines. 30. How and why the compensating winding in dc machine excited? PART –A 1. What are the three basic rotating Electric machines? 2. Name the three materials used in machine manufacture. 3. What is magneto motive force? 4. Define Leakage flux and leakage inductance. 5. Explain Flux Fringing at air – gap . 6. Write short note on stacking factor and give its value . 7. Give the classification of material based on relative permeability μr . 8. Define relative permeability μr . 9. What is B-H curve and sketch it ? 10. Define Faraday’s law of induction. 11. What is Lenz’s law? 12. Define statically induced emf and dynamically induced emf . 13. Write the Lorentz force equation. 14. Give few magnetic properties. 15. What is magnetic permeability ? TRANSFORMERS ________________________________________ 1. What is a Transformer? 2. Enumerate the various kinds of transformers. 3. Why is the transformer windings are divided into several coils ? 4. Draw the phasor diagram of an ideal transformer. 5. Give the two general types of transformer. 6. What is an air – core transformer? 7. Draw the equivalent circuit of single phase transformer. 8. Name the two tests that are used to determine parameters of equivalent circuit, voltage regulation and efficiency. 9. State the different losses in transformer. 10. Define hysteresis and eddy current losses. 11. What is Steinmetz’s constant and give its range. 12. Define efficiency and All day efficiency. 13. Enumerate the various testing of transformers. 14. What is Auto – transformer? 15. Distinguish between transformer and Auto – transformer. 16. What is tap- changer ? 17. Classify the various types of tap- changer. 18. What are the different three phase connections? 19. What is the EMF equation of a transformer? 20. Define voltage regulation. 21. What is transformation ratio? 22. At what frequency core loss and iron loss are equal? 23. What is polarity test in transformers? 24. What is equivalent resistance of transformer ? How it is calculated in primary terms ? 25. Define all- day efficiency . 26. What is equivalent reactance of transformer ? How it is calculated in primary terms ? 27. What are the two components of core loss ? 28. Draw the phasor diagram of inductive and capacitive load. 29. At what condition core loss and iron loss equal ? 30. Define voltage transformation ratio. 1.Voltage variable voltage capacitor is also called as () a)zener diode b)pn junction diode c)varactor diode d) tunnel diode 2.The diode which exhibit negative resistance under low forward biased conditions is a)zener diode b)tunnel diode c)pn junction diode d) varactor diode 3. Ripple factor of full wave rectifier a)1.21 b)0.48 c)81.2 d)40.6 4.Zener diode can be used to regulate the voltage across a load under --- condition a)Reverse bias breakdown b)forward bias c)reverse bias d) none of the above 5.Voltage controlled device is also called as a)fet b)bjt c)bipolar device d) none of above 6.Zener breakdown has --- temperature coefficient a)negative b)positive c)not depends on temperature d)none of above 7.The impurity concentration is high in which type of diode a)tunnel b)zener c)pn d)varactor 8.Which transistors are more temperature stable a)bjt b)fet c)b0th d)none of these 9.The angle of each rc section is rc phase shift oscillator is a)180 b)60 c)360 d)120 10.The gain of amplifier in fet phase shift oscillator 11. Rc phase shift oscillator generates signals of frequency a)Rf b)Af c)Hf d)none 12.The feed back in wein bridge oscillator is called as a)lag-lead network b)lead-lag network c)positive feedback d)negative feedback network 13.The gain of wein bridge 14.The phase shift introduced by feed back in wein bridge a)0 b)180 c)60 d)120 15.The frequency of oscillations generated by lc tank circuit a)0 b)180 c)60 d)120 16.In alloy type transistor diffusion is made up of a)iridium b)germanium c)indium d)silicon 17.Punch through effect is also called as a)enter through effect b)reach through effect c)pass through effect d)none of these 18.Jfet is also called as a)current variable resistance b)voltage variable resistance c)current constant resistance d)voltage constant resistance 19.In active region the emitter base junction is – bias and collector base junction is --- biased a)forward, reverse b)forward, forward c)reverse ,forward d)reverse, reverse 20. In which type of configuration the current gain is minimum 1. common base b) common emitter c)common collector d) none of these EDC KEY 1) 2)produc t of concentration of electrons and holes is always constant at fixed temperature np=n*i*i 3)space charge, barrier depletion layer 4)zener and avalanche 5)if first element is an inductor it is called choke input filter 6) 7)2L,1C,180 degrees 8) 9) 10)pierce crystal, miller crystal 11)RR=ripple content in output/ripple content in input 12)when reverse bias voltage increases the width of the depletion region increases which reduces the bandwidth 13) 14)alarm systems,counting systems 15)they alter externally generated illumination 16)GaAS, GaAsP, GaP 17) 18)mosfet has no pn junction structure instead gate of mosfet is insulated from channel by silicon dioxide 19) 20)load current increases for constant dc output voltage , RL decreases. This increases the ripple contents in output. 21) 22)diffusion or storage capacitance 23)40.6% 24) 25) current caused due to flow of current towards positive terminal 1)c 2) 3)a 4)a 5)a 6)a 7)a 8)b 9)a 10) 11)b 12)b 13) 14)a 15) 16)c 17)b 18)b 19)a 20)a NETWORK ANALYSIS 1. what is current if a 10 coulomb charge passes a point in 0.5 sec 2. What are passive elements? 3. What is the internal resistance of a ideal voltage source? 4. If a network contains B branches and N nodes, then the number of mesh equations? 5. What is the phasor difference between voltage and current for a pure inductor? 6. What is coefficient of coupling? 7. What is power factor? 8. Define reactive power? 9. Which parameters are widely used in transmission line theory? 1. 1.Define power and energy. 2. .What are bilateral and unilateral elements 3. What are lumped and distributed elements 4. State KCL and KVL 5. Write the voltage-current relation of an inductor. 6. Comment on supernode analysis 7. State thevenins theorem 8. Write the condition for maximum power transfer. 9. What is steady state response 10. Give the time constant for RL circuit. 11. What is critical damping? 12. What is the natural resonant frequency of RLC circuit? 13. Define impedance 14. Write the complete response of the sinusoidal excited RC circuit 15. Define path and loop. 16. Define electric current 17. Define electric resistance 18. Define electric conductance 19. Define specific resistance 20. Differentiate electric power and energy 21. Define electromotive force 22. State ohms law 23. State kirchoff’s law 24. What is an alternating quantity? 25. Define cycle 26. Define time period 27. Define frequency 28. Define amplitude 29. Define RMS value 30. Define average value 31. Define the expression for form factor and peak factor 32. Define power factor 33. What do you understand by balanced system? 34. What is an indicating instrument? 35. Write two essential requirements of indicating instruments 36. List the three different torques employed in the measuring instruments for the satisfactory operation 37. Write any four methods by which the deflecting torque can be obtained 38. Mention the two methods of obtaining controlling torque 39. What is meant by damping torque? 40. Write any two features of moving coil instrument 41. Write any two features of moving iron instrument 42. What is meant by creeping? 43. What is back emf? 44. Why a dc series motor cannot be started on no load? 45. What are the various types of dc motors? 46. What is the necessity of a starter for a dc motor? 47. What is torque? 48. What is speed regulation? 49. What is called armature torque? 50. What is called shaft torque? 51. Draw the characteristics curve of a dc shunt motor? 52. What is the difference between three point and four point starters? 53. What is the method available for testing dc series motor? 54. Name the protective devices used in a 3point starter? 55. Mention the methods of speed control for a dc motor? 56. What are the losses that occur in a dc motor? 57. What are the various types of dc generators? 58. Draw the internal and external characteristic curves of dc shunt generator? 59. Draw the internal and external characteristic curves of dc series generator? 60. Draw the characteristics curves of dc compound generator? 61. DC series generators are suitable for ? 62. What is the function of commutator in DC generator? 63. What is the function of carbon brushes in DC generator? 64. What is called voltage regulation? 65. Write short notes on efficiency of a DC motor? 66. How the voltage builds up in Dc generator? 67. Why the armature core is made by laminated sheets? 68. Explain the construction and working principle of D.C. generator 69. Explain the different types of D.C. generators. 70. Draw and explain the characteristics of different types of d.c.generators. 71. Derive the emf equation of D.C. Generator. 72. Explain the principle of working a 1-phase transformer? 73. Discuss the difference between core type and shell type construction? 74. What is KVA rating of a transformer? 75. Draw the no load phasor diagram of a transformer? 76. Draw the phasor diagram of a transformer under load condition? 77. Explain voltage regulation? 78. Derive the emf equation of a transformer? 79. What is meant transformation ratio? 80. How the transformers are classified? 81. Write short notes on autotransformer. 82. Derive the condition for maximum efficiency? 83. What are the various losses that must be present in a transformer? 84. Explain the construction and working principle of single-phase transformer. 85. Enumerate the various types of transformer. 86. Derive an expression for the emf of an ideal transformer winding. 87. Draw and explain the no load phasor diagram for a single-phase transformer. 88. What is KVA rating of a transformer? 89. Explain various features of an ideal transformer. 90. What is the frequency of induced emf of an induction motor? 91. Why squirrel cage induction motors are common in the domestic pump sets? 92. Distinguish between squirrel cage & slip ring induction motor? 93. What are the applications of induction motors? 94. Name the speed control methods of a 3 induction motors? 95. Define a slip of an induction motor? 96. What is called synchronous speed? 97. Define electron volt? 98. State the relationship between electric field intensity, and potential?
Posted on: Sun, 20 Oct 2013 09:52:38 +0000
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