JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III MATERIALS CHARACTERIZATION Previous Question Paper (August - 2022 - R18)
Answer any five questions. All questions carry equal marks.
Main
What is polarized light? Explain the applications of polarized light microscopy.
Answer
Polarized light refers to light waves in which the vibrations occur in a single plane, rather than in all directions perpendicular to the direction of propagation. In polarized light microscopy, a polarizer is placed before the specimen to produce plane-polarized light, and an analyzer is placed after the specimen to observe the interaction of light with anisotropic materials.
Applications include:
- Identification of minerals and crystalline materials based on their birefringence properties.
- Analysis of stress distribution in transparent polymers and glass, known as photoelasticity.
- Examination of biological specimens such as starch grains, collagen fibers, and muscle tissues that exhibit optical anisotropy.
- Characterization of liquid crystals and synthetic polymers to determine molecular orientation and crystallinity.
What is the limit of resolution of a microscope with numerical aperture 1.45 and wavelength 600nm?
Answer
The limit of resolution (d) of a microscope is defined by the Abbe equation:
Given:
- Wavelength (λ) = 600 nm
- Numerical Aperture (NA) = 1.45
Substituting the values into the formula:
The limit of resolution for the microscope is approximately 252.41 nm.
How resolving power and magnification are related?
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What is quantitative metallography? Explain its importance.
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What are the different types of modes used in SEM? Explain its applications.
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Explain the advantages, limitations and applications of SEM.
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Explain construction and working principle of TEM.
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Differentiate between bright field and dark field in TEM.
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What is depth of field and depth of focus in TEM?
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Explain the advantages, limitations and applications of TEM.
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What are the different factors affecting the relative intensity of the diffraction lines on a powder pattern?
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Explain any two factors affecting the diffraction intensities.
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Explain the procedure to determine the stress in materials by X-ray diffractometry.
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What is Scherrer’s formula? Derive its expression.
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