1. Explain the formation of depletion region in a p-n junction.
2. Describe the working action of p-n junction diode under forward bias and reverse bias.
3. Draw the energy band diagram of a p-n junction diode.
4. Discuss V-I characteristics of a p-n junction diode.
5. Draw the V-I characteristic of Zener diode and explain its operation.
6. Explain the terms : (i) Static resistance (ii) Dynamic resistance (iii) Junction
resistance and (iv) Reverse resistance of a diode.
7. Define the term transition capacitance CT of a p-n junction diode. Explain.
8. Explain the term diffusion capacitance CD of a forward biased diode.
9. Explain the effect of temperature of a diode.
10. Describe various breakdown mechanisms.
11. Draw the equivalent circuit of a diode and explain it.
12. Explain in detail load line analysis of p-n junction diode.
1. Define diffusion capacitance.
2. Define transition capacitance.
3. Differentiate between Zener breakdown and avalanche breakdown mechanisms.
4. Explain how unidirectional current flow is possible through a p-n junction diode.
5. Explain the following terms in a p-n junction diode
i. Maximum forward current
ii. Peak inverse voltage.
6. A silicon diode has a saturation current of 7.5 µA at room temperature 3000 K.
7. Calculate the saturation current at 4000 K.
8. What are the applications of a diode?
9. Define operating point.
1. Briefly discuss application of p-n junction as half wave rectifier.
2. Differentiate between drift and diffusion currents.
3. Discuss the avalanche and breakdown voltage of Zener diode and also discuss the Zener diode as a voltage regulator.
4. Discuss the avalanche breakdown and Zener breakdown.
5. Draw and explain the V-I characteristics of a solar cell.
6. Draw neat energy band diagrams for symmetrically doped p-n junction when it is (i) unbiased (ii) forward biased and (iii) reverse biased.
7. Draw the V-I characteristics of a simple photo diode. What is meant by dark current?
8. Explain construction and discuss I-V characteristics of the following semiconductor devices (i) photo diode (ii) solar cell
9. Explain how a Zener diode maintains constant voltage across the load.
10. Explain the phenomenon of photo voltaic effect.
11. Explain the working of a solar cell.
12. Give a brief note on the principle, construction and working of LED. What are advantages and disadvantages?
13. In a p-n junction, what are the diffusion and drift currents? Hence explain the expression of depletion layer.
14. Sketch typical illumination characteristics for a photo diode and explain the theory device.
15. What are the parameters of solar cell?
16. What causes majority carriers to flow at the moment when P region and N region brought together? Why does this flow not continue until all the carriers have recombine?
17. What is an LED? Explain the construction and working of LED.
1. What is meant by photoconductivity?
2. What is meant by photovoltaic emf?
3. What is reverse breakdown?
4. What is reverse saturation current in a diode?
5. Why is reverse saturation current independent of reverse bias?
6. Write a short note on solar cells.
7. Write short notes on (i) solar cell (ii) p-n junction diode.
1. Draw the circuit diagram of a half wave rectifier using p-n junction diode and explain its working.
2. Draw the circuit diagram of a full wave rectifier using p-n junction diode and explain its operation.
3. In case of half wave rectifier, derive expression for
(i) Average and r m s values of current
(ii) Rectifier efficiency
(iii) Ripple factor.
4. In case of full wave rectifier, derive expression for
i) Average and r m s values of current
ii) Rectifier efficiency
iii) Ripple factor.
1. Define rectifier efficiency, ripple factor and regulation.
2. What is a filter circuit? Give the advantage of a filter in the output circuit of a rectifier. Discuss the use various filters to avoid ripples.
3. What are different types of filters used? Give their comparative study.
4. Describe the working of full wave rectifier with a shunt capacitance filter. Why for low ripple factor the output current should be very small.
5. What is rectification? Show with diagrams how a diode is used as half wave rectifier and full wave rectifier.
6. Draw a circuit diagram of full wave rectifier along with a series inductor filter and ripple factor formula.
7. Give a circuit diagram full wave rectifier using L- section filter and explain its working.
8. Give a circuit diagram full wave rectifier using π- section filter and explain its working.
9. Mention the advantages of using a filter circuit in the output of rectifier circuit. Explain the smoothing action of inductance input and capacitance input filters.
1. Explain what is dc power supply?
2. Explain what is rectifier?
3. Explain what is PIV of a diode in a rectifier circuit?
4. Explain what is the important of peak inverse voltage?
5. Explain why half wave rectifiers are generally not used in dc power supply?
6. Explain why diodes are not operated in the breakdown region in rectifiers?
7. Define ripple factor referred to in a rectifier circuit.
8. The output of 60 Hz full wave bridge rectifier has a 60 Hz ripple. It this circuit working properly?
9. Explain what is meant by filter?
10. Why series inductor and L- section filters cannot be used with half wave rectifier?
11. Explain why capacitor input filter is preferred to choke input filter?
12. Explain why π – filters are not suitable for varying loads?
13. Explain why R – C filters are suitable for only for light loads?
14. Explain why is bleeder resistance employed in a filter circuit?
Explain what is meant by voltage regulation of a dc power supply?
1. What is a transistor? How it is biased?
2. Explain the mechanism of current flow in a p-n-p transistor?
3. Describe the operation of n-p-n transistor.
4. Explain the current components in a transistor.
5. In a transistor operating in a active region, although the collector junction is reverse biased, the collector current is quite large. Explain.
6. Name the three possible transistor connections. Explain the operation of transistor as an amplifier.
7. Explain the principle and working of a common emitter transistor amplifier. Comment on the advantage of the CE configuration.
8. Show different current components in a transistor and prove
9. Explain the transistor action. Describe how p-n-p transistor characteristics are experimentally studied. Discuss the use of transistor for amplification.
10. Define α. Show that it is always less than unity and define β and show that β=α/(1-α)
11. Sketch a family of CB characteristics for a transistor. Clearly indicate the cut off, active and saturation regions.
12. Sketch a family of CE characteristics for a transistor. Clearly indicate the cut off, active and saturation regions.
1. What is transistor? Name the regions and junctions that a transistor has.
2. Why emitter size is in between sizes of base and collector?
3. Why emitter region is more doped than collector and base regions?
4. What is cut off, saturation and active regions?
5. What is current amplification factor? Write expressions for current amplification factors in CB, CE and CC configurations.
6. Derive the relation between α,β, and γ.
1) What are different configurations of FET?
2) Explain the input and output characteristics of a transistor in CE configuration.
3) Derive the relationship between α and β.
4) Explain the construction of N channel JFET.
5) With the help of neat sketches and characteristic curves explain the operation of the junction FET.
6) How does the FET behave for small and large values of VDS?
7) Define pinch-off voltage VP. Sketch the depletion region before and after pinch-off.
8) Compare JFET with BJT.
9) Explain why BJTs are called bipolar devices while FETs are called unipolar devices.
10) Assuming that the saturation drain current IDS is given by the parabolic relation .
Prove that the transconductance gm is given by
1) Distinguish between DC and AC load lines with suitable diagrams.
2) Explain the operation of n-p-n and p-n-p transistors.
3) What is meant by Q-point and what is the need for biasing a transistor? What factors are to be considered for selecting the operating point Q for an amplifier?
4) Briefly explain the reasons for keeping the operating point of a transistor as fixed.
5) Draw a fixed bias circuit and derive an expression for the stability factors.
6) If the coordinates of the operating point of a CE amplifier using fixed bias (or base resistor) method of biasing are VCE = 6 V and IC = 1 mA, determine the value of RC and RB. (Ans: RC = 3 kΩ and RB = 300 kΩ).
7) Derive an expression for the stability factor of collector-to-base bias circuit.
8) Draw a circuit diagram of CE transistor amplifier using emitter biasing. Describe qualitatively the stability action of the circuit.
9) Draw a voltage divider bias circuit and derive an expression for its stability factor.
10) Why does the potential divider method of biasing become universal?
1. Draw the energy band diagram of a PN Junction under unbiased condition and obtain an expression for potential barrier.
2. With necessary circuit diagrams, explain the working of a PN junction diode in forward and reverse bias conditions.
3. What is Zener diode? Explain the operation of a Zener diode in forward bias and reverse bias conditions.
4. Differentiate between Zener breakdown and Avalanche breakdown mechanisms.
5. Explain the construction, working and characteristics of a photodiode.
1. Explain the principle, construction and working of LED. What are the advantages and disadvantages of it.
2. Differentiate between Radiative and non-Radiative recombination mechanism in semiconductors.
3. Explain the construction and working of a semiconductor diode laser.
4. Explain the construction and V-I characteristics of the following semiconductor devices. (i) PIN (ii) Solar cell
5. Discuss various photo detectors.
1. Draw the circuit diagram of a full wave rectifier using p-n junction diode and explain its operation.
2. Describe the working of full wave rectifier with a shunt capacitance filter. Why for low ripple factor the output current should be very small.
3. Draw a circuit diagram of full wave rectifier along with a series inductor filter and ripple factor formula.
4. Give a circuit diagram of full wave rectifier using L- section filter and explain its working.
5. Give a circuit diagram of full wave rectifier using π- section filter and explain its working.
1. Describe the operation of n-p-n transistor.
2. Derive the relation between α, β, and γ.
3. Explain CB configuration with neat diagram and describe input and out characteristics of CE configuration.
4. Explain the principle and working of a common emitter transistor amplifier. Comment on the advantage of the CE configuration.
5. Compare the performance of a transistor in different configurations.
1. (a) What is Q-point?
(b) What is thermal runway? How can it be avoided?
2. Derive an expression for the stability factor of (i) Fixed bias (ii) collector to base bias
3. Draw a voltage divider bias circuit and derive an expression for its stability factor.
4. Draw a circuit diagram of CE transistor amplifier using emitter biasing. Describe qualitatively the stability action of the circuit.
5. Explain the construction of N-channel JFET. How does the transfer and drain characteristics vary?