Name of the College : Sphoorthy Engineering College
University : JNTUH
Department : Metallurgy And Material Technology
Subject Code/Name : 09A51801/BASIC ELECTRONICS
Year : December 2011
Degree : B.Tech
Year/Sem : III/I
Website : sphoorthyengg.com
Document Type : Model Question Paper
Download Model/Sample Question Paper : https://www.pdfquestion.in/uploads/sphoorthyengg.com/4820-09A51801%20-%20BASIC%20ELECTRONICS.pdf
Sphoorthy Basic Electronics Question Paper
B. Tech III Year I Semester Examinations, December-2011
(METALLURGY AND MATERIAL TECHNOLOGY)
Time: 3 hours
Max. Marks: 75
Related : Sphoorthy Electrical Machines–III B.Tech Question Paper : www.pdfquestion.in/4849.html
Model Questions
Answer any five questions :
All questions carry equal marks :
Set – I
1.a) Describe the phenomenon of diffusion of charge carriers in the semiconductor.
b) Draw the energy band diagram of P-N junction and explain the working of a diode. [7+8]
2.a) The resistivities of the P-region and N-region of a silicon diode are 6ohms-cm and 4ohms-cm respectively. Calculate the contact potential Voand potential energy barrier Eo.if the doping densities of both P and N regions are tripled. Determine Vand E. Given data q =1.6oo×10C ni = 1.5 19-×1010 /cm , 3pµ=500cm /v-s 2nµ=1300cm/v-s and vT= 0,026v at 3000K. 2
b) Derive an expression for ripple factor for full wave rectifier with C-filter. [7+8]
3.a) Explain the principle of NPN and PNP transistor. How are its terminals named?
b) Define pinch-off voltage V?.Sketch the depletion region before and after pinch- off. [7+8] p
4.a) With the V-I characteristics describe the working principle of an SCR.
b) Explain the terms.
i) Firing angle
ii) Conduction angle of an SCR. [7+8]
5.a) Draw a Darlington emitter follower. Explain why the input impedance is higher than that of a single stage emitter follower.
b) Draw the small signal model of common source amplifier and derive an expression for voltage gain and output impedance. [7+8]
6.a) Describe the construction of phase shift oscillator and explain its working.
b) Drive the expression for the frequency of oscillation and the minimum gain required for sustained oscillations of the RC phase shift oscillator. [7+8]
7.a) Explain the following type of Timers.
i) Electro-mechanical Timers.
ii) Electronic Timers.
b) List different welding circuits
c) Explain Projection welding process. [15]
8.a) Giving basic set up, explain the principle of Induction heating.
b) Draw and explain the heat control circuit for resistance welding. [15]
Set – II
R09Code No: 09A51801
SET-2
1.a) Describe the action of P-N junction diode under forward bias and reverse bias.
b) Explain the Hall Effect. How can Hall Effect be used to determine some of the properties of a semiconductor? [7+8]
2.a) Find the concentration of holes and electrons in a P-type silicon at 300K. assuming resistivity as 0.020O-cm assume pµ=500cm /v-s, ni = 1.5 2×1010 /cm 3
b). Explain the action of bridge rectifier and give waveforms of input and output voltages. [7+8]
3.a) What is the relation between I, I and I in Common base configurations? BEC
b) Explain the early effect and sequences.
c) What are the different configurations of BJT? [15]
4.a) What is TRAIC? Sketch its characteristics and describe its operation.
b) Explain why an SCR is operated only in the forward biased condition. [7+8]
5.a) Draw the frequency response of an amplifier and the reason for different slopes in the response.
b) Explain how does negative feedback reduce distortion in an amplifier. [7+8]
6.a) What are the different types of negative feedback? Explain how the inputs and output impedances of an amplifier are affected by the different types of negative feedback.
b) The distortion in an amplifier is found to be 3% when the feedback ratio of a negative feedback amplifier is 0.04. When the feedback is removed, the distortion becomes 15% . Find the open loop gain and closed loop gain. [7+8]
7.a) Name principal types of resistance welding processes and briefly explain them.
b) List different applications of Ultrasonic Waves and explain the principle and working of Pulsed-echo Ultrasonic Flow Detector. [7+8]
8. Write a short note on:
a) Resistance wielding.
b) Timer circuits
c) Dielectric heating. [15]
Set – III
Answer any five questions
All questions carry equal marks
1.a) Derive an expression for a ripple factor in a full wave rectifier with resistive load.
b). A half wave rectifier has a load at 3.5kO. if the diode resistance and secondary coil resistance together have a resistance of 800O and input voltage has a signal voltage of peak value 240v calculate
i) Peak, average and RMS value of current following
ii) DC power output
iii) Efficiency of the rectifier. [7+8]
2.a) Sketch the conduction and valence bands before and after diffusion of carriers in a P-N junction.
b) Explain the majority and minority carriers in the semiconductor. [7+8]
3.a) Explain the input and output characteristics of a transistor in CE configuration.
b) Determine the h-parameters from the characteristics of CB configurations. [7+8]
4.a) Explain how triggering of an SCR can be controlled by the gate signal supplied.
b) What is the advantage of TRAIC over the SCR? [7+8]
5.a) Enumerate the effects of negative feedback on the various characteristics of the amplifier.
b) Describe with necessary derivation, the effect of negative feedback on the bandwidth and distortion in an amplifier. [7+8]
6.a) State and briefly explain Barkhausen criterion for oscillation.
b) Draw the circuit diagram of a general oscillator and obtain the maintenance condition and the frequency of oscillations. [7+8]
7.a) Draw and explain the heat control circuit for resistance welding.
b) Compare and contrast the following timers:
i) Thermal Timers
ii) Electro-mechanical Timers
iii) Electronic Timers. [7+8]
8.a) Giving basic set up, explain the principle of Induction heating.
b) Explain the principle of Dielectric heating. [7+8]
Set – IV
Answer any five questions
All questions carry equal marks
1. a) Derive the relationship between modulation index and total power of an AM signal.
b) You are given the voltage signals x(t) and cos2pfct, and you wish to produce the AM waveform x(t) cos2pfct. Discuss two practical methods of generating this AM waveform. [7+8]
2. a) What is a simple automatic gain control? What are its functions?
b) Derive an expression for (S/N)d for an SSB system. [7+8]
3. a) Compare narrow band FM with wide band FM.
b) An angle modulated waveform is described by 7()10cos21020cos1000xttpp?=×+? . Find the approximate bandwidth of this waveform. [7+8]
4. a) Describe the spectral representation of PWM and PPM waves.
b) Draw the block diagram of PCM scheme showing the elements required for the transmission and explain. [7+8]
5. a) What is inter symbol interference? How is it minimized?
b) Explain the various techniques to detect the base band digital signals. [7+8]
6. a) Derive the expression for the spectrum of BPSK and sketch the same.
b) Explain M-ary FSK systems with the help of transmitters and receivers. [7+8]
7. a) State the significance of H(Y/X) and H(X/Y).
b) Apply Huffmann’s encoding procedure to the following message ensemble and determine the average length of the encoded message. {}{}{}{}12345678910,,,,,,,,,0.18,0.17,0.16,0.15,0.10,0.08,0.05,0.05,0.04,0.02XxxxxxxxxxxPX==
The encoding alphabet is {}{}0,1,2,3.D= [7+8]