Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech IV MATERIAL CHARACTERIZATION TECHNIQUES Previous Question Paper (March - 2021 - R15)
Answer any Five Questions. All Questions Carry Equal Marks.
Main
Explain the principle of optical microscope and its operation.
Answer
The optical microscope operates on the principle of magnification through the interaction of visible light with a specimen. It utilizes a combination of lenses to create a magnified virtual image of an object. The light source passes through a condenser lens to illuminate the specimen uniformly. The objective lens then collects light scattered or transmitted by the specimen to form a real, magnified intermediate image. Finally, the eyepiece (ocular) further magnifies this intermediate image, allowing the observer to view a virtual, inverted, and highly magnified image.
Operation involves: 1. Mounting the specimen on a glass slide. 2. Adjusting the light intensity and condenser position for optimal illumination. 3. Using the coarse adjustment knob to bring the specimen into approximate focus. 4. Using the fine adjustment knob to achieve a sharp image. 5. Switching between objective lenses to increase magnification as required, ensuring the specimen remains centered.
Write about the applications of optical spectroscopy.
Answer
Optical spectroscopy is a powerful analytical technique used to study the interaction between matter and electromagnetic radiation. Its primary applications include:
- Chemical Composition Analysis: Identifying elements and compounds in a sample by analyzing characteristic absorption or emission spectra.
- Concentration Determination: Using Beer-Lambert's Law to quantify the concentration of solutes in a solution based on light absorbance.
- Material Characterization: Determining the bandgap of semiconductors and studying electronic transitions in materials.
- Molecular Structure Identification: Utilizing infrared (IR) spectroscopy to identify functional groups within organic and inorganic molecules.
- Quality Control: Monitoring purity levels in industrial manufacturing processes and environmental testing for pollutants.
- Thin Film Analysis: Measuring the thickness and optical constants of thin films using techniques like ellipsometry.
Explain the significance of Numerical aperture in optical microscopy.
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Discuss in detail about interference and polarized light microscopy.
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With the help of a neat diagram explain the Construction and working principle of SEM.
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Discuss the following terms in SEM: i) Working Distance ii) Depth of Field iii) Depth of Focus iv) Spot Size.
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Explain the principle, construction and working principle of TEM with the help of a diagram.
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Write down the applications, advantages, and limitations of TEM.
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Discuss in detail the scattering by an electron, scattering by an atom and scattering by a unit cell.
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Explain various factors that affect diffraction intensities.
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Explain the detailed procedure of chemical analysis by XRD.
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Explain the Electromagnetic Spectrum and UV-Visible Absorption Spectra.
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Explain the principle of Infrared spectroscopy.
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Explain the procedure of study of NMR Patterns.
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Explain differential Scanning Calorimetry.
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