JNTU
JNTU B.Tech III ELECTRICAL ENGINEERING MATERIALS Previous Question Paper (November/December - 2018 - R16)
Note: This question paper contains two parts A and B. 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
Enumerate characteristics of dielectrics with respect to their valance band.
Answer
In dielectrics, the valence band is completely filled with electrons, and there is a large energy band gap between the valence band and the conduction band. This large gap prevents electrons from gaining sufficient energy to jump into the conduction band under normal conditions, making the material an electrical insulator.
What is meant by orientation polarization?
Answer
Orientation polarization occurs in polar dielectrics where molecules possess a permanent electric dipole moment. In the absence of an external electric field, these dipoles are randomly oriented due to thermal agitation. When an external field is applied, the dipoles tend to align themselves in the direction of the field, resulting in a net polarization.
Steel is ferromagnetic but is not a magnet in the absence of magnetic field why?
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What are the special purpose magnetic materials?
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What is meant by Bridgman method of semiconductor growth?
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Write the most fitting semiconducting materials for solar cells.
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Give the applications of brass and bronze as a low resistivity material?
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How do the lightly loaded contacts differ from heavily loaded contacts?
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What is meant by impregnation of the material?
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What is the effect of temperature on the insulating property of transformer oil?
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PART - B
What do you mean by dielectric loss? Explain loss factor, how do you calculate the loss factor.
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Explain structure and properties of Barium Titanate as a promising ferroelectric material.
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Explain how do you find out breakdown strength of solid dielectric material.
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Briefly describe the significance of pyroelectric effect on pyroelectric devices.
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Explain the phenomenon of magnetic anisotropy and discuss its importance for magnetic materials.
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Explain the concept of cast and cermet permanent magnets and use of such magnet.
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Distinguish between soft magnetic material and hard magnetic material.
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What are the different factors effecting permeability and hysteresis in magnetic materials?
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Discuss in detail, the stepwise methodology to manufacture the silicon wafer.
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Write the most suitable semiconducting materials for integrated circuit and describe structure of LSI.
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What are the materials used for stranded conductors and write their composition.
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Explain in brief characteristic features of thermocouple materials.
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What are the properties of gaseous insulating materials and describe moisturizing effect on these materials?
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Describe the composition of radioactive materials and also its applications.
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Describe the properties and applications of mineral oils.
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With the help of suitable diagrams, describe stepwise, the method of galvanization of materials.
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