JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Tech III Year MATERIALS CHARACTERIZATION Previous Question Paper (February - 2023 - R18)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
What is called resolving power?
Answer
Resolving power is the ability of an optical instrument to distinguish between two closely spaced objects as separate entities. It is defined by the minimum distance between two points at which they can still be perceived as distinct rather than a single blurred image.
How does the numerical aperture affect the resolution of a microscope?
Answer
Numerical aperture (NA) is directly proportional to the resolution of a microscope. According to the Abbe diffraction limit, the resolution limit (d) is given by:
As the numerical aperture increases, the value of d decreases, meaning the microscope can resolve finer details. A higher NA allows the collection of more diffracted light, leading to a sharper and more detailed image.
What is depth of focus in SEM?
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What are the applications of SEM?
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How depth of field in TEM is defined?
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Why are thin sections of specimen necessary in TEM?
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Who has invented X-rays and when?
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What is X-ray diffractometry?
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What is Gibb’s phase rule?
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What are different types of stresses present in materials when subjected to deformation? Explain.
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Part B
Explain the principle of phase contrast in optical microscopy.
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Explain the image formation in light microscopy.
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Explain about quantitative metallography using optical microscope.
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Draw the line diagram of SEM and explain the functions of each component.
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Explain the advantages and limitations of SEM.
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Explain the different methods of specimen preparation in SEM.
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Compare and contrast between TEM and SEM.
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Explain about instrumentation of TEM.
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Briefly discuss about image modes of TEM.
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Briefly discuss about electron beam source and condenser lens in TEM.
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Show that short wavelength limit of a continuous spectrum depends only on the applied voltage.
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Explain the factors on which the total intensity of the continuous spectrum depends.
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Explain the order-disorder arrangements observed in FeNi3, MnNi3 etc with neat sketches.
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Though CuZn is fully ordered the ratio of intensity of super lattice and fundamental lines is only 0.0003. Explain the necessary reasons. Explain the procedure how the value 0.0003 is arrived.
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What is the smallest value of θ at which CrKα doublet will be resolved in a 5.73cm diameter Hull/Debye-Scherrer camera? Assume that the line width is 0.03cm and that the separation must be twice the width for resolution.
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Explain about Guiner cameras.
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X-rays with a wavelength of 0.60A are used for calculating d200 in nickel. The reflecting angle is 9.50. Calculate the size of the unit cell.
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Explain why diffraction lines with diffraction angle equal to 1800 give accurate lattice parameters.
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