**B.Sc. (Final Year) Semester IV**\
**Subject: Physics**\
**Course Name: Analog Electronics (PHY253)**\
**Full Marks: 60**\
**Time: 3 Hours**
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### **Section A** (Very Short Answer Questions)
*(Answer any 7 questions. Each question carries 1 mark.)*\
**(1×7 = 7 Marks)**
1. Define drift velocity.
2. What is a PN junction?
3. Mention any one application of a Zener diode.
4. What is the function of a rectifier?
5. Define common-emitter current gain (β).
6. What is the Q-point of a transistor?
7. Mention any one characteristic of an ideal Op-Amp.
8. What is a comparator?
9. State Barkhausen's criterion for oscillations.
10. What is the role of a CRO in waveform analysis?
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### **Section B** (Short Answer Questions)
*(Answer any 4 questions. Each question carries 2 marks.)*\
**(2×4 = 8 Marks)**\
11\. Explain the concept of barrier potential in a PN junction.\
12\. Differentiate between half-wave and full-wave rectifiers.\
13\. Describe the active region of a transistor.\
14\. What are the advantages of negative feedback in amplifiers?\
15\. Explain the working principle of an RC phase shift oscillator.\
16\. What is a virtual ground in an Op-Amp circuit?
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### **Section C** (Medium Answer Questions)
*(Answer any 3 questions. Each question carries 5 marks.)*\
**(5×3 = 15 Marks)** *(Five options given)*\
17\. Describe the energy band diagram of a semiconductor.\
18\. Explain the working of a Zener diode as a voltage regulator.\
19\. Draw and explain the hybrid model of a transistor.\
20\. Discuss the classification of amplifiers based on Class A, B, and C operation.\
21\. Explain the working of a two-stage RC-coupled amplifier with a neat diagram.
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### **Section D** (Long Answer Questions)
*(Answer any 3 questions. Each question carries 10 marks.)*\
**(10×3 = 30 Marks)** *(Six options given)*\
22\. Derive an expression for the current in a PN junction diode under forward and reverse bias.\
23\. Explain the working of a bridge rectifier with a circuit diagram.\
24\. Describe the physical mechanism of current flow in a bipolar junction transistor (BJT).\
25\. Derive the expression for gain in an inverting and non-inverting Op-Amp amplifier.\
26\. Discuss in detail the working principle of a Colpitt’s oscillator.\
27\. Explain the block diagram of a Cathode Ray Oscilloscope (CRO) and its applications.
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