JNTU
JNTU B.Tech III BASIC ELECTRONICS Previous Question Paper (May - 2018 - R15)
Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
Write the diode equation based on underlying physical laws.
Answer
The diode current equation, also known as the Shockley diode equation, is given by:
Where I is the diode current, Is is the reverse saturation current, V is the applied voltage, η is the ideality factor (1 for Ge, 2 for Si), and VT is the thermal voltage (kT/q).
Draw V-I characteristics curve of photo diode.
Answer
The V-I characteristics of a photodiode are plotted in the third quadrant because it operates in reverse bias. The curve shows a series of parallel lines for different incident light intensities (Φ), where the reverse current increases linearly with light intensity.
Draw the NPN transistor symbol and name its terminals.
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Derive the output voltage equation for CC configuration.
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Draw and name the terminals of SCR.
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Compare Diac and Triac.
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Write the different Classification of oscillators.
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Write the advantages of negative feedback amplifier.
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What is welding?
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Write the applications Ultrasonic generators.
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Part B
Explain the operation of Full Wave Rectifier without filter with necessary diagrams.
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Draw and explain the energy band diagram for intrinsic semiconductor.
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Draw the circuit diagram of a half – wave rectifier with L - section filter for producing a positive output voltage and also sketch the input and output waveforms, and explain the circuit operation.
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Explain active region, saturation region and cut-off region in transistor with suitable diagram.
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Draw and explain the Frequency response of Common Emitter Amplifier with necessary equations.
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Explain the different methods of turning on SCR.
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Explain how SCR can be used in circuit breaker and over voltage protection.
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Explain different triggering modes of TRIAC.
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Draw two transistor analogy of SCR and describe its working.
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Draw the circuit of a voltage series feedback circuit and explain it.
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What are the possible amplifiers circuits in any feedback system? Discuss.
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Derive the expressions for Av, Zi, Z0 and Ai of a voltage shunt feedback amplifier.
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Write short notes on Timing circuits used in welding processes.
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List the methods of generation of ultrasonic waves and also list any eight applications of ultrasonic waves.
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List various Industrial applications of dielectric heating.
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Explain the theory and principle of dielectric heating.
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