07a1bs03 Engineering Physics

Code No. 07A1BS03

UNIT-3 ENGINEERING PHYSICS

Magnetic properties and Superconductivity 1. a) Explain the following (i) Permeability (μ) (ii) Magnetic field of intensity (H) b) What are the applications of superconductors? c) Mercury isotopic mass 199.5 at 4.185 K.Calculate its critical temperature when its isotopic mass changes to 203.4. 2. a) Derive an expression for μr = (1 + χ) b) Explain the concept of super conductivity. c) A superconducting material critical temperature is 5K at a pressure of 1mm of Hg, Calculate critical temperature at a pressure of 6mm of Hg. 3. a) Discuss magnetic moment in detail. b) Mention the Type- I and Type- II superconductors. c) An electron in an atom circulates in an orbit of radius 0.052 nm. Calculate the change in its magnetic moment if magnetic field of 1 weber/m2 acts perpendicular to the plane of orbit. 4. a) Explain Bohr Magneton in detail. b) Discuss d.c Josephson’s effect. c) The area of the hysteresis loop drawn between B and H is 100m2. Each unit space along the vertical axis represent 0.01wb/m2 and each unit space along the horizontal axis represents 40 amp/m. Determine the hysteresis loss per cycle. 5. a) Explain the classification of magnetic materials. b) Discuss about hard and soft super conductors. c) A lead superconductor with Tc = 7.2 K has a critical magnetic field of 6.5 x 103 A m-1 at absolute zero. What would be magnitude of critical magnetic field at 5 K temperature. 6. a) Explain the importance of magnetic materials. b) What are the cooper pairs? Explain. c) At 6 K critical field is 5 x 103 A m-1 calculate the transition temperature. Where critical magnetic field is 2 x 104 A m-1 at 0K. 7. a) Explain the hysteresis curve on the basis of domain theory. b) Explain about Meissner effect. c) A magnetic field of 1800 amp/m produces a magnetic flux of 3 x 10-5 Wb in an iron bar of cross sectional area 0.2 cm2. Calculate permeability.

8. a) Explain how ferrites are superior to ferromagnetic materials. b) What are the properties of super conductors? c) A superconducting material critical temperature is 5K at a pressure of 1mm of Hg, Calculate critical temperature at a pressure of 6mm of Hg. 9. a) Explain the hysteresis curve in detail. b) Explain about critical magnetic field (Hc). c) A magnetic material has a magnetization of 3000 amp/m flux density of 0.005 Weber/m2. Calculate the magnetic force and the relative permeability of the material. 10. a) Mention the applications of ferrites. b) Explain the phenomenon of BCS theory. c) Josephson junction having a voltage of 8.50 μV across its terminals then calculate its generating EM waves frequency. 11. a) Discuss about Ferrites b) Discuss the phenomenon of flux quantization. c) The magnetic susceptibility of silicon is -0.5 x 10-5, what is the intensity of magnetization and magnetic flux density in a magnetic field of intensity 9.9 x 104 amp/m. 12. a) Explain domain theory of Ferro magnetism. b) Mention the applications of superconductors c) A super conductor with Tc = 3.5K has a critical magnetic field of 3.2 x103 A m-1 at absolute zero. What would be the value of critical field at 2.5 K temperature. 13. a) Explain about magnetic materials on the basis of electron spin. b) Explain the phenomenon of BCS theory. c) Calculate for the critical current for a wire of Pb having a diameter of 3mm at 5K.the critical temperature for a Pb is 8K and critical field is 5 x 104 A m-1 at 0K. 14. a) Discuss the applications of superconductors. b) What is Bohr Magneton? How it is related to magnetic moment of electron? c) The area of the hysteresis loop drawn between B and H is 100m2. Each unit space along the vertical axis represent 0.01wb/m2 and each unit space along the horizontal axis represents 40 amp/m. Determine the hysteresis loss per cycle.

15. a) What is penetration depth? Explain. b) Explain the hysteresis curve in detail. c) A superconductor ring radius r is 0.02m and its critical magnetic field is 2 x 103 A m-1 at 5K. What is its critical current value. 16. a) Mention Type- I and Type- II superconductors. b) Mention the applications of ferrites. c) Circular loop conductor of radius 0.04m carries a current of 1000 mA. The loop is placed in magnetic field of flux density 10-3 Wb/m2 with its axis inclined at 45o to the direction of the field. Calculate the magnetic dipole moment and the torque on the coil. 17. a) Distinguish between hard and soft super conductors. b) Discuss hysteresis curve in detail. c) Find the relative permeability of a Ferro magnetic material if field of strength 220 amp/meter produces a magnetization 3300 amp/meter in it. 18. a) Phenomenon of flux quantization- Explain. b) Discuss hard and soft magnetic materials. c) The transition temperature for lead is 8.7K. The maximum critical field for the material is 6 x 105 A m-1. Lead as to be used has a superconductor subjected to magnetic field of 3 x106 A m-1. 19. a) Mention the properties of super conductors? b) Explain the hysteresis curve on the basis of domain theory. c) Mention the uses of magnetic materials 20. a) Explain the concept of super conductivity. b) Differentiate between hard and soft super conductors. c) An electron in an atom circulates in an orbit of radius 0.052 nm. Calculate the change in its magnetic moment if magnetic field of 1 weber/m2 acts perpendicular to the plane of orbit. 21. a) Derive an expression for μr = (1 + χ) b) Explain domain theory of Ferro magnetism. c) What are the applications of superconductors? 22. a) Discuss the phenomenon of BCS theory. b) Mention the applications of superconductors. c) Circular loop conductor of radius 0.04m carries a current of 1000 mA. The loop is placed in magnetic field of flux density 10-3 Wb/m2 with its axis inclined at 45o to the direction of the field. Calculate the magnetic dipole moment and the torque on the coil.

23. a) Explain hysteresis curve in detail. b) Explain Type- I and Type- II superconductors. c) Mention the applications of superconductors. 24. a) Distinguish between hard and soft super conductors. b) Explain the uses of magnetic materials. c) The area of the hysteresis loop drawn between B and H is 100m2. Each unit space along the vertical axis represent 0.01wb/m2 and each unit space along the horizontal axis represents 40 amp/m. Determine the hysteresis loss per cycle. 25. a) Discuss hard and soft magnetic materials. b) Explain about cooper pairs. How they produces superconductivity in materials. c) Mercury isotopic mass 199.5 at 4.185 K.Calculate its critical temperature when its isotopic mass changes to 203.4 26. a) Explain about Ferromagnetic materials. b) Explain importance of magnetic materials. c) Mercury isotopic mass 199.5 at 4.185 K. Calculate its critical temperature when its isotopic mass changes to 203.4 27. a) Define the terms (i) Critical Magnetic field (Hc). (ii) Critical Current. b) Find the relative permeability of a Ferro magnetic material if field of strength 220 amp/meter produces a magnetization 3300 amp/meter in it. 28. a) Discuss hard and soft magnetic materials. b) Write a short note on domain theory of Ferro magnetism. c) Discuss d.c and a.c Josephson’s effects. 29. a) Explain the phenomenon of flux quantization. b) What are the applications of superconductors? c) Mention the uses of magnetic materials 30. a) Distinguish between hard and soft super conductors. b) What are the applications of superconductors? c) The transition temperature for lead is 8.7K. The maximum critical field for the material is 6x105 A m-1. Lead as to be used has a superconductor subjected to a magnetic field of 3 x 106 A m-1.

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Code No. 07A1BS03

UNIT-4 ENGINEERING PHYSICS

CRYSTAL STRUCTURES & X – RAY DIFFRACTION 1. a) Define the terms space lattice and unit cell b) Describe the structure of ZnS. c) The density of Schottky defects in a certain sample of Nacl is 5 x 1011/m3 at 25o C. If the interionic (Na+-cl-) distance is 2.82Ao, what is the energy required to create one schottky defect. 2. a) Define packing fraction and primitive cell. b) Describe the structure of CsCl. c) The concentration of Schottky defects in an ionic crystal is 1 in 1010 at a temperature of 300K. Estimate the average separation in terms of the lattice spacings between the defects at 300K and calculate the value of concentration to be expected at 1000K. 3. a) What is the expression for density of the crystal in terms of lattice constant? b) What is space lattice? Find the packing fraction for SC and BCC crystals. c) Show that the maximum radius of the sphere that can just fit into the void at the body centre of FCC structure coordinated by the facial atoms is 0.414r, where r is the radius of the atom. 4. a) Describe the seven crystal systems with diagrams. b) Distinguish between BCC and FCC crystal structures. 5. a) What is Barvais lattice? What are the different space lattices in the cubic system. b) Explain the principle, procedure and advantage of Debye- Scherrer method (Powder method) of X- ray diffraction. 6.

a) Derive the packing fraction value for a crystal belonging to simple cubic crystal. b) Describe with suitable diagram, the Laue’s method of determination of crystal structure. c) An electron initially at rest is accelerated through a potential difference 5000 Volts. Calculate the Braggs angle for first order of reflection from (111) planes which are 0.204 nm apart.

7.

a) What is space lattice? Find the packing fraction for SC, BCC and FCC crystals. b) Describe with suitable diagram, the Bragg’s spectrometer to determine the crystal.

8. a) Describe the structure of ZnS.

b) Explain the principle, procedure and advantage of Debye- Scherrer method (Powder method) of X- ray diffraction. 9.

a) Find the packing fraction for SC, BCC and FCC crystals. b) Discuss the schottky defects in ionic crystals. c) A powder pattern is obtained for lead with radiations of wavelength= 1.50oA. then (202) reflected diffraction is observed at Bragg’s angle θ = 34o.What is the lattice parameter of lead? Assume that the given reflection is the first order of reflection.

10. a) How does the number if Schottky defects in a crystal vary with temperature? b) Explain why Frankel defects occur in crystals? 11. a) Distinguish between Frenkel and Schottky defects? b) Describe with suitable diagram, the Laue’s method of determination of crystal structure. 12. a) Derive an expression for Frenkel defect concentration in a ionic crystal? b) Describe with suitable diagram, the Bragg’s spectrometer to determine the crystal. 13. a) Derive an expression for the number of vacancies at a given temperature? b) What is space lattice? Explain. c) A mono energetic electron beam of kinetic energy 232.2 eV undergoes first order reflection at the glancing angle. 9o12ˈ. What is the inter planer spacing of the reflection planes. 14. a) Distinguish between SC and BCC crystals. b) Explain the principle, procedure and advantage of Debye- Scherrer method (Powder method) of X- ray diffraction. 15. a) Show that FCC crystals are closely packed than BCC crystals. b) Describe the Laue’s method of determination of crystal structure. c) Lithium crystallizes in BCC structure. Calculate the lattice constant, given that the atomic weight and density for lithium are 6.94 and 530 Kg/m3 respectively. 16. a) Describe the structure of sodium chloride crystal. b) How does the number if Schottky defects in a crystal vary with temperature? 17. a) Draw the structure of Diamond? b) Derive an expression for the number of vacancies at a given temperature? 18. a) Distinguish between Frenkel and Schottky defects? b) How does the number if Schottky defects in a crystal vary with temperature? c) Iron crystallizes in BCC structure. Calculate the lattice constant, given

that the atomic weight and density of iron are 55.85 and 7860 Kg/m3 respectively. 19. a) Describe the seven crystal systems with diagrams. b) Explain why Frankel defects occur in crystals? 20. a) Define packing fraction and primitive cell. b) How are the vacancies created in a lattice? c) Ge crystallizes in diamond (form) structure with 8 atoms per unit cell. If the lattice constant is 5.62A. Calculate its density. 21. a) Derive an expression for the interplanar spacing between two adjacent planes of miller indices (hkI) in a cubic lattice of edge length a. b) What is space lattice? Find the packing fraction for FCC crystal. c) Calculate the number of atoms per unit cell of a metal with lattice parameter 2.9 Ao. Molecular weight 55.85, density = 7870Kgm-3 and avagadro number 6.02 X 1026 Kg.mol-1 22. a) Explain the significance of Miller indices. b) Describe the structure of CsCl. c) Copper has FCC structure and its atomic radius is 0.1278 nm. Calculate its density. Take the atomic weight of cooper as 63.5 a.m.u. 23. a) Derive Bragg’s law of X- ray diffraction. b) Describe the seven crystal systems. c) Show that the maximum radius of the sphere that can just fit into the void at the body centre of FCC structure coordinated by the facial atoms is 0.414r, where r is the radius of the atom. 24. a) Describe the Bragg’s spectrometer to determine the crystal. b) Show that FCC crystals are closely packed than BCC crystals. c) What is the angle at which the third order of reflection of X –rays of 0.79 Ao wavelength can occur in a calcite crystal of 3.04 X 10-8 cm spacing. 25.

a) Find the packing fraction for BCC? b) Explain the principle & procedure of Debye- Scherrer method (Power method) of X- ray diffraction. c) A powder pattern is obtained for lead with radiations of wavelength= 1.50oA. Then (202) reflected diffraction is observed at Bragg’s angle θ = 34o.What is the lattice parameter of lead? Assume that the given reflection is the first order of reflection.

26. a) Explain the schottky defects in ionic crystals. b) Derive Bragg’s law of X- ray diffraction. c) A mono energetic electron beam of kinetic energy 232.2 eV undergoes first order reflection at the glancing angle. 9.12’25”. What is the inter planer spacing of the reflection planes.

27. a) Explain why Frankel defects occur in crystals. b) Describe, the Laue’s method of determination of crystal structure. c) The density of Schottky defects in a certain sample of Nacl is 5 X 1011/m3 at 25o C. If the interionic (Na+-cl-) distance is 2.82Ao, what is the energy required to create one schottky defect. 28. a) Describe the seven crystal systems. b) Explain the significance of Miller indices. c) Lithium crystallizes in BCC structure. Calculate the lattice constant, given that the atomic weight and density for lithium are 6.94 and 530 Kg/m3 respectively. 29.

a) Describe the Bragg’s spectrometer to determine the crystal. b) Distinguish between Frenkel and Schottky defects. c) What is the angle at which the third order of reflection of X –rays of 0.79Aowavelength can occur in a calcite crystal of 3.04 X 10-8 cm spacing.

30. a) Derive an expression for the number of vacancies at a given temperature. b) Describe the seven crystal systems with diagrams. 31. a) Explain the terms basis and unit cell. b) What are Miller indices? Explain. c) A beam of X- rays of wavelength 0.071 nm is diffracted by (110) plane of rock salt with lattice constant of 0.28nm. Find the glancing angle for the second order of diffraction. -oOo-

Code No. 07A1BS03

UNIT-5 ENGINEERING PHYSICS

Laser 1. a) Explain characteristics of laser. b) With the help of suitable diagrams, explain the principle, construction and working of He- Ne gas laser. 2. a) Explain the following i) Absorption ii) Stimulated emission b) Describe the construction and working of a Ruby laser. 3. a) What is population inversion in laser? How is it achieved? b) Explain with neat diagram spontaneous emission and stimulated emission. 4. a) Derive the relation between the probabilities of spontaneous emission and stimulated emission in terms of Einstein’s coefficients. b) Explain in detail direct band gap semiconductors. 5. a) Distinguish between spontaneous emission and stimulated emission. b) Mention the applications of laser in the field of medicine. c) Gas has band gap energy of 1.43 eV at 300 K. Determine the wavelength above which an intrinsic photo detector fabricated from this material will cease to operate. 6. a) What is laser? Explain how the basic lasing action is achieved. b) With the help of a suitable diagrams, explain the mechanism of a semiconductor laser. 7. a) Why is population inversion necessary to achieve lasing? b) Derive the relation between the probabilities of spontaneous emission and stimulated emission in terms of Einstein’s coefficients. 8. a) Explain about absorption and stimulated emission. b) With the help of suitable diagrams, explain the principle, construction and working of He- Ne gas laser. 9. a) Describe the construction and working of a Ruby laser. b) Distinguish between Homojunction semiconductor laser and Hetero junction semiconductor laser. 10. a) Explain the purpose of active medium in the resonator. b) With the help of suitable diagrams, explain the principle, construction and working of He- Ne gas laser. 11. a) What is stimulated emission? Describe lasing action in laser.

b) Distinguish between Homojunction semiconductor laser and Hetero junction semiconductor laser. 12. a) Explain the working of semiconductor laser. b) Derive the relation between the probabilities of spontaneous emission and stimulated emission in terms of Einstein’s coefficients. 13. a) With the help of a suitable diagrams, explain the mechanism of a semiconductor laser. b) Explain with neat diagram spontaneous emission and stimulated emission. 14. a) With the help of suitable diagrams, explain the principle, construction and working of He- Ne gas laser. b) Mention the applications of laser in the field of engineering. c) Energy gap of semiconductor is 3 eV. Calculate wavelength of emitted photons. 15. a) Mention the applications of laser in the field scientific research and medicine. b) With the help of suitable diagrams, explain the principle, construction and working of He- Ne gas laser. 16. a) What is stimulated emission? Explain. b) Mention applications of laser in the field of engineering and medicine. c) Gas has band gap energy of 1.43 eV at 300 K. Determine the wavelength above which an intrinsic photo detector fabricated from this material will cease to operate. 17. a) Explain the need of active medium in a gas laser. b) Discuss about indirect band gap semiconductors. c) A matter wave propagating with a velocity 3 x103 m/s and its wavelength 600mm. Calculate the matter wave energy. 18. a)

Derive the relation between the probabilities of spontaneous emission and stimulated emission in terms of Einstein’s coefficients. b) With the help of suitable diagrams, explain the construction and working of He- Ne gas laser.

19. a) Explain the with neat diagram absorption, spontaneous emission and stimulated emission. b) Derive the relation between the probabilities of spontaneous emission and stimulated emission in terms of Einstein’s coefficients. 20. a) Explain about coherence and absorption. b) Discuss in detail direct band gap semiconductors c) Energy gap of semiconductor is 3 eV. Calculate wavelength of emitted photons.

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