Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech I ENGINEERING PHYSICS Previous Question Paper (January/February - 2024 - R15)
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 packing fraction?
Answer
The packing fraction (PF) of a crystal structure is defined as the ratio of the volume occupied by the atoms in a unit cell to the total volume of the unit cell. It represents the efficiency of atomic packing in a crystal lattice and is expressed as:
How Miller Indices are useful to identify crystal planes in an FCC lattice?
Answer
Miller indices are a set of three integers (h, k, l) used to uniquely identify specific crystal planes within an FCC lattice by defining their orientation relative to the unit cell axes. In an FCC structure, these indices are determined by taking the reciprocals of the fractional intercepts that the plane makes with the crystallographic axes (x, y, z), expressed in terms of lattice parameters, and then reducing them to the smallest set of integers.
These indices are essential for identifying planes because:
- They define the spacing between parallel planes, known as interplanar spacing (d), which is critical for analyzing diffraction patterns in X-ray crystallography.
- They allow for the classification of planes with high atomic density, such as the (111) plane in FCC, which is the most closely packed plane and significantly influences the slip systems and plastic deformation behavior of the material.
- They provide a standardized notation to describe the geometry of the lattice, ensuring that equivalent planes—such as (100), (010), and (001)—are correctly identified as belonging to the same family of planes {hkl}.
Describe the significance of Davisson and Germer's experiment in the context of quantum mechanics.
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What are matter waves?
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Define electric dipole moment.
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What is dielectric constant?
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Explain the characteristics of a laser.
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What is population inversion?
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Identify the factors affecting architectural acoustics.
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Explain Hall Effect.
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Part B
Given an X-ray diffraction angle (2θ) of 45° and an X-ray wavelength of 0.1 nm, use Bragg’s Law to calculate the interplanar spacing in a crystal.
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Describe the structure of a Sodium Chloride (NaCl) crystal. Discuss its bonding, coordination number.
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Describe the Powder Method in X-ray diffraction and its advantages over the Laue Method.
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Calculate the atomic packing factor for a Body-Centered Cubic (BCC) lattice, given that the atomic radius is 'r'.
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Explain the concept of 'Density of States' in the context of electron theory in solids and its significance in determining the electronic properties of materials.
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How does the concept of Infinite Square well potential apply to quantum mechanics, and how is it extended to three dimensions?
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Compare and contrast Bose-Einstein and Fermi-Dirac Statistics.
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Explain the significance of the E-K curve and the origin of energy band formation in solids.
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Discuss the concept of internal fields in dielectric solids.
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Describe the properties of anti-ferromagnetic and ferrimagnetic materials and their applications.
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Compare and contrast electronic, ionic, and orientation polarizations in dielectrics.
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Explain the domain theory of ferromagnetism and analyze the features of a hysteresis curve.
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Describe the diffraction grating experiment and its applications in measuring wavelengths of light.
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Discuss Einstein's coefficients and their relation between them.
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Discuss the theory of Fraunhofer diffraction due to a single slit and its significance.
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Explain the concepts of acceptance angle and numerical aperture in fiber optics.
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Estimate carrier concentration in intrinsic semiconductors of conduction band.
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Describe Sabine's formula for reverberation time and its application in acoustic design.
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Discuss the I-V characteristics of a PN junction diode and its practical implications.
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Compare and contrast the synthesis of nanomaterials using sol-gel and Chemical Vapor Deposition (CVD) techniques.
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