B.Sc. DEGREE EXAMINATION, MAY 2012.
(Examination at the end of Second Year)
Part II — Electronics
Paper II — ELECTRONIC DEVICES AND CIRCUITS
Time : Three hours Maximum : 100 marks
Answer any FIVE questions.
All questions carry equal marks.
1. (a) Explain Intrinsic and Extrinsic semiconductors.
(b) Explain in detail about forward and reversive bias of a diode with V-I characteristics.
2. (a) How does the band theory of solids lead to the classification of solids into conductors,
semiconductors and insulators?
(b) Mobilities of electrons and holes in a sample of intrinsic germanium at room
temperature are 0.36mv
/v-sec and 0.17 m2
/v sec respectively. If the electron and hole
densities are each equal to 2.5 × 1019m–3, calculate the electrical conductivity of
Germanium.
3. (a) Sketch the CE input characteristics for a BJT and explain their shape.
(b) Differentiate between the action of a NPN and PNP transistor in view of operation.
4. (a) Differentiate between small signal and large signal amplifiers.
(b) Explain the classification of amplifiers based on conduction angle and coupling.
5. (a) What is meant by feedback in amplifiers? Define negative and positive feedback.
(b) Explain how negative feedback in amplifiers helps in improving gain stability and
reducing the distortion.
6. (a) Draw the circuit diagram of a colpits oscillator and explain its operation.
(b) Differentiate between an amplifier and an oscillator.
7. (a) Describe the construction and working of MOSFET.
(b) Explain its various biasing model.
8. (a) Describe the structure and working of UJT giving schematic and equivalent circuits.
(b) Mention some application of UJT.
9. Explain with proper circuit diagram the construction, working and uses of a LED.
10. Describe the construction and working of SCR. What do you infer from the characteristics
(Examination at the end of Second Year)
Part II — Electronics
Paper II — ELECTRONIC DEVICES AND CIRCUITS
Time : Three hours Maximum : 100 marks
Answer any FIVE questions.
All questions carry equal marks.
1. (a) Explain Intrinsic and Extrinsic semiconductors.
(b) Explain in detail about forward and reversive bias of a diode with V-I characteristics.
2. (a) How does the band theory of solids lead to the classification of solids into conductors,
semiconductors and insulators?
(b) Mobilities of electrons and holes in a sample of intrinsic germanium at room
temperature are 0.36mv
/v-sec and 0.17 m2
/v sec respectively. If the electron and hole
densities are each equal to 2.5 × 1019m–3, calculate the electrical conductivity of
Germanium.
3. (a) Sketch the CE input characteristics for a BJT and explain their shape.
(b) Differentiate between the action of a NPN and PNP transistor in view of operation.
4. (a) Differentiate between small signal and large signal amplifiers.
(b) Explain the classification of amplifiers based on conduction angle and coupling.
5. (a) What is meant by feedback in amplifiers? Define negative and positive feedback.
(b) Explain how negative feedback in amplifiers helps in improving gain stability and
reducing the distortion.
6. (a) Draw the circuit diagram of a colpits oscillator and explain its operation.
(b) Differentiate between an amplifier and an oscillator.
7. (a) Describe the construction and working of MOSFET.
(b) Explain its various biasing model.
8. (a) Describe the structure and working of UJT giving schematic and equivalent circuits.
(b) Mention some application of UJT.
9. Explain with proper circuit diagram the construction, working and uses of a LED.
10. Describe the construction and working of SCR. What do you infer from the characteristics
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