nmu.ac.in Question Paper : North Maharashtra University

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Type of Announcement : Question Paper

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Electronics Model Question Paper
I. Crystal Structure
I. 1) Explain the term co-ordination number.
2) Explain the term packing fraction.
3) What is primitive translational vector?
4) Explain the idea of unit cell.
5) What is the atomic radius? What is the atomic radius for FCC crystals?
6) Write the values of the packing fraction of SC and FCC.
7) Calculate the packing fraction of BCC crystals.
8) State the properties of reciprocal lattice.
9) What are the Millar indices of a plane?
10) Explain Millar Indices.

II. 1) What is Millar Indices? What are Millar Indices of a plane making intercepts 2a, 3b, 6c on three axes.
2) Show that packing fraction of FCC and SC structures are 0.74 and 0.52 respectively.
3) Draw neat diagrams of SC and BCC structures.
4) Draw neat diagrams primitive lattice cell of SC and BCC structures.
5) Show that reciprocal of a reciprocal lattice is the original lattice.

II. Band theory of solids
I. 1) What is energy band?
2) Explain the concept of hole.
3) Explain origin of energy bands in crystals.
4) Describe in brief free electron model.
5) Draw energy band of conductors and semiconductors.

II. 1) Distinguish between conductors, insulators and semiconductors with energy band diagram.
2) Discuss electronic motion according to band theory.
3) Write a note on free electron theory model.
4) Write a note on hole.

III. Charge carriers in semiconductor
I. 1) What is intrinsic semiconductor?
2) What is extrinsic semiconductor?
3) What is direct semiconductor? Give example
4) What is indirect semiconductor? Give example
5) What is Fermi energy?
10) Give the expression of hole concentration in valence band.
11) Explain Hall effect in material
12) Explain Hall coefficient.

Questions for 4 marks
1) Explain Fermi-dirac distribution function against temperature.
2) Derive the expression of electron concentration in conduction band.
3) Derive the expression of hole concentration in valence band.
4) Explain Hall effect with diagram.
5) Explain Fermi level and Fermi energy.
6) Derive the expression for mobility and electrons in electronic and magnetic field.
7) What is Hall effect? Obtain an expression for Hall coefficient.
8) Distinguish between direct and indirect semiconductor.
(Note: Question of 4 marks may be asked for 6 marks expecting more detail answer)

Unit IV: P-N Junction and Integrated Circuits
Questions for 2 marks
1) Give different steps in fabrication of P-N junction.
2) Mention different methods of fabrication of P-N junction.
3) Explain donar impurity.
4) Explain acceptor impurity.
5) What is the contact potential?
6) How monolithic circuits are fabricated/
7) What is merged transistor?
8) Explain forward bias P-N junction.
9) Explain reverse bias P-N junction.
10) Explain current flow at junction.

Questions for 4 marks
1) Explain Zener break down process.
2) Explain donar and acceptor impurities in semiconductors.
3) Explain the Avalaunche break down process in P-N junction.
4) Write a note on reverse break down.
5) Explain how monolithic circuits are fabricated.
6) Explain the idea of merged transistors.
7) Write a note on monolithic circuits.
8) Explain in short MOS transistors.
9) Explain how BJT is fabricated.
10) Describe diffusion method of fabrication of P-N junction.
11) Explain the Zener break down in reverse bias P-N junction.
12) Explain forward and reverse bias of P-N junction.
13) What is depletion layer in P-N junction? How does the potential barrier in the region change with doping levels.
14) Describe in brief contact potential.

T.Y.B.Sc. Electronics (Paper II)
ELE.312 Basic Communication Systems
Unit 1: Communication System
Questions for 2 marks
1) Define modulation. State its types.
2) What is mean by communication process? State the elements of modern communication system.
3) What are the advantages of modulation process in the modern communication system?
4) Draw only the block diagram of modern electronic communication system.
5) Define amplitude modulation.
6) Define frequency modulation.
7) Define phase modulation.
8) What do you mean by carrier wave? Give its importance in modulation process.
9) Modulation process increases the range of communication, comment.
10) Modulation process allows multiplexing of signals, comment.
11) Modulation process reduces antenna height, comment.
12) Modulation process avoids mixing of signals, comment.
13) The process of modifying a high frequency carrier in accordance with the low frequency modulating signal is called as ___________.
14) A signal, with which original electrical information sent, is called as __________signal.
15) Define noise in modern communication systems.

Questions for 4 marks
1) Draw the block diagram of modern communication system. Explain each block in brief.
2) What do you mean by modulation? Define AM, FM and PM.
3) Explain how it is possible to reduce antenna height and to avoid mixing of signals by using modulation process.
4) Explain how it is possible to increase range of communication and to avoid mixing of signals by using modulation process.
5) Explain how it is possible to multiplex the signals and to adjust the band width of signals by using modulation process.
6) Explain the concept of modulation process. Explain how quality of signal improved by using this process.
7) What is mean by communication process? Compare traditional trends of communication with modern trend of electronic communication.
8) If the modulation process not used then for the transmission of a signal of 20 KHz frequency, the length of transmitting antenna will be approximately 1/4th of the wavelength of the wave. Estimate the height of receiving antenna.
9) Explain in brief the importance of transmitter and receiver in modern communication system.
10) Explain about communication channel and noise source in modern communication system.
11) Draw the block diagram of modern electronic communication system and explain transmitter section.
12) Draw the block diagram of modern electronic communication system and explain about communication channel.
13) Draw the block diagram of modern electronic communication system and explain about receiver section involved in it.
14) Draw the block diagram of modern electronic communication system. Explain how noise affects on the system performance.
15) Explain how antenna height reduces by employing modulation technique in modern communication systems.
16) Explain the following terms in one sentence each, i) Radio wave, ii) Modulating signal, iii) Carrier signal and iv) Noise
17) Explain in brief the need of modulation process in modern communication systems.

Questions for 6 marks
1) With the help of block diagram, explain modern communication system in detail.
2) In modern communication system, explain the following blocks, i) Transmitter ii) Receiver iii) Channel iv) Noise
3) Explain the need of modulation in response to antenna height, long distance communication, multiplexing of signals and improved signal quality.
4) Define modulation process. State its types. Explain the need of it in modern electronic communication systems.