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APPLIED PHYSICS, exams, Study notes of Applied Chemistry

B.Tech Semester Supplimentary Examinations, June 2009 APPLIED PHYSICS Bragg’s law, Schrodinger’s wave equation, Fermi energy, neat diagram i. absorption ii. spontaneous emission and iii. stimulated emission of radiation. BCC and FCC lattices, Schottky and Frenkel defects, Burgers vector, Hall effect, Laue’s method, Fermi-Dirac distribution, Davison and Germer experiment, Meissner effect, Miller indices, Ruby laser

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Code No: R05010201 Set No. 1
I B.Tech Semester Supplimentary Examinations, June 2009
APPLIED PHYSICS
( Common to Electrical & Electronic Engineering, Electronics &
Communication Engineering, Computer Science & Engineering, Electronics
& Instrumentation Engineering, Bio-Medical Engineering, Information
Technology, Electronics & Control Engineering, Computer Science &
Systems Engineering, Electronics & Telematics, Electronics & Computer
Engineering and Instrumentation & Control Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆⋆⋆⋆⋆
1. (a) Explain the terms [6]
i. basis
ii. space lattice and
iii. unit cell.
(b) Describe the seven crystal systems with diagrams. [10]
2. (a) State and explain Bragg’s law. [6]
(b) Describe with suitable diagram, the powder method for determination of crys-
tal structure. [6]
(c) A beam of X-rays of wavelength 0.071 nm is diffracted by (110) plane of rock
salt with lattice constant of 0.28 nm. Find the glancing angle for the second
order diffraction. [4]
3. (a) Derive time independent Schrodinger’s wave equation for a free particle. [8]
(b) Explain the physical significance of wave function. [4]
(c) An electron is bound in a one-dimensional infinite well of width 1 ×1010m.
Find the energy values in the ground state and first two excited states. [4]
4. (a) Explain the origin of energy bands in solids.
[6]
(b) Assuming the electron - lattice interaction to be responsible for scattering of
conduction electrons in a metal, obtain an expression for conductivity in terms
of relaxation time and explain any three draw backs of classical theory of free
electrons. [6]
(c) Find the temperature at which there is 1% probability of a state with an
energy 0.5 eV above Fermi energy. [4]
5. (a) Explain how the magnetic materials are classified from the atomic point of
view. [6]
(b) What are the differences between hard and soft magnetic materials. [6]
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I B.Tech Semester Supplimentary Examinations, June 2009 APPLIED PHYSICS ( Common to Electrical & Electronic Engineering, Electronics & Communication Engineering, Computer Science & Engineering, Electronics & Instrumentation Engineering, Bio-Medical Engineering, Information Technology, Electronics & Control Engineering, Computer Science & Systems Engineering, Electronics & Telematics, Electronics & Computer Engineering and Instrumentation & Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆ ⋆ ⋆ ⋆ ⋆

  1. (a) Explain the terms [6] i. basis ii. space lattice and iii. unit cell. (b) Describe the seven crystal systems with diagrams. [10]
  2. (a) State and explain Bragg’s law. [6] (b) Describe with suitable diagram, the powder method for determination of crys- tal structure. [6] (c) A beam of X-rays of wavelength 0.071 nm is diffracted by (110) plane of rock salt with lattice constant of 0.28 nm. Find the glancing angle for the second order diffraction. [4]
  3. (a) Derive time independent Schrodinger’s wave equation for a free particle. [8] (b) Explain the physical significance of wave function. [4] (c) An electron is bound in a one-dimensional infinite well of width 1 × 10 −^10 m. Find the energy values in the ground state and first two excited states. [4]
  4. (a) Explain the origin of energy bands in solids. [6] (b) Assuming the electron - lattice interaction to be responsible for scattering of conduction electrons in a metal, obtain an expression for conductivity in terms of relaxation time and explain any three draw backs of classical theory of free electrons. [6] (c) Find the temperature at which there is 1% probability of a state with an energy 0.5 eV above Fermi energy. [4]
  5. (a) Explain how the magnetic materials are classified from the atomic point of view. [6] (b) What are the differences between hard and soft magnetic materials. [6]

(c) A magnetic material has a magnetization of 3300 ampere / m and flux density of 0.0044 wb / m^2. Calculate the magnetizing force and the relative perme- ability of the material. [4]

  1. (a) What is meant by superconductivity? Explain. [6]

(b) Show that the superconductors are perfect diamagnetic materials. [6] (c) Write some of the applications of superconductors. [4]

  1. (a) Explain with a neat diagram

i. absorption ii. spontaneous emission and iii. stimulated emission of radiation. [8] (b) What is population inversion? How it is achieved by optical pumping? [8]

  1. (a) What is meant by an acceptance angle for an optical fibre? Obtain mathe- matical expressions for acceptance angle and numerical aperture (NA). [10] (b) An optical fibre has a NA of 0.20 and cladding refractive index of 1.59. Deter- mine the acceptance angle for the fibre in water which has a refractive index of 1.33. [6]

(b) Write a note on diffusion length. [6] (c) The resistivity of an intrinsic semiconductor is 4.5 ohm-m at 20 oC and 2.0 ohm-m at 32 oC. What is the energy band gap? [4]

  1. (a) Explain with a neat diagram

i. absorption ii. spontaneous emission and iii. stimulated emission of radiation. [8] (b) What is population inversion? How it is achieved by optical pumping? [8]

  1. (a) Explain the basic principle of an optical fibre. [4]

(b) Describe graded index optical fibre and explain the transmission of signal through it. [8] (c) What are different losses in optical fibres? Write brief note on each. [4]

I B.Tech Semester Supplimentary Examinations, June 2009 APPLIED PHYSICS ( Common to Electrical & Electronic Engineering, Electronics & Communication Engineering, Computer Science & Engineering, Electronics & Instrumentation Engineering, Bio-Medical Engineering, Information Technology, Electronics & Control Engineering, Computer Science & Systems Engineering, Electronics & Telematics, Electronics & Computer Engineering and Instrumentation & Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆ ⋆ ⋆ ⋆ ⋆

  1. (a) Define coordination number and packing factor of a crystal. [4] (b) Describe the FCC crystal structure. [6] (c) Obtain an expression for the packing factor of FCC structure. [6]
  2. (a) Sketch the following planes of a cubic unit cell: (001), (120) and (¯211). [3] (b) Explain Bragg’s law of X-ray diffraction. [5] (c) Describe Laue’s method for determination of crystal structure. [8]
  3. (a) Describe in detail, with a neat diagram, Davison and Germer experiment to show that particles behave like waves. [10] (b) Electrons are accelerated by 344 Volts and are reflected from a crystal. The first reflection maximum occurs when the glancing angle is 60o. Determine the spacing of the crystal. [6]
  4. (a) What is Fermi level? [2] (b) Explain Fermi-Dirac distribution for electrons in a metal. Discuss its variation with temperature. [8] (c) Calculate the free electron concentration, mobility and drift velocity of elec- trons in aluminum wire of length of 5 m and resistance 0.06 Ω carrying a current of 15 A, assuming that each aluminum atom contributes 3 free elec- trons for conduction. Given: Resistivity for aluminum = 2.7× 10 −^8 Ω-m. Atomic weight = 26. Density = 2.7 × 103 kg/ m^3 Avagadro number = 6.025 × 1023 [6]
  5. (a) What is meant by hysteresis in magnetic materials? [6] (b) What are magnetic domains? Explain hysteresis basing on domain theory. [10]
  6. (a) Explain Meissner effect. [6]

I B.Tech Semester Supplimentary Examinations, June 2009 APPLIED PHYSICS ( Common to Electrical & Electronic Engineering, Electronics & Communication Engineering, Computer Science & Engineering, Electronics & Instrumentation Engineering, Bio-Medical Engineering, Information Technology, Electronics & Control Engineering, Computer Science & Systems Engineering, Electronics & Telematics, Electronics & Computer Engineering and Instrumentation & Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆ ⋆ ⋆ ⋆ ⋆

  1. (a) Explain the terms [6] i. basis ii. space lattice and iii. unit cell. (b) Describe the seven crystal systems with diagrams. [10]
  2. (a) Sketch the following planes of a cubic unit cell: (001), (120) and (¯211). [3] (b) Deduce the expression for the inter-planar distance in terms of Miller indices for a cubic structure. [8] (c) Calculate the ratio d 100 : d 110 : d 111 for a simple cubic structure. [5]
  3. (a) Describe edge and screw dislocations. Draw Burgers circuit and slip planes for them. [10] (b) Explain the significance of Burgers vector. [6]
  4. (a) What is Fermi level? [2] (b) Explain Fermi-Dirac distribution for electrons in a metal. Discuss its variation with temperature. [8] (c) Calculate the free electron concentration, mobility and drift velocity of elec- trons in aluminum wire of length of 5 m and resistance 0.06 Ω carrying a current of 15 A, assuming that each aluminum atom contributes 3 free elec- trons for conduction. Given: Resistivity for aluminum = 2.7× 10 −^8 Ω-m. Atomic weight = 26. Density = 2.7 × 103 kg/ m^3 Avagadro number = 6.025 × 1023 [6]
  5. (a) How magnetic materials are classified? Explain with suitable examples. [10] (b) Write notes on the following: [6] i. Curie temperature

ii. Magnetic Susceptibility.

  1. (a) Explain d.c. Josephson effect. [6]

(b) Describe the BCS theory of superconductivity. [6] (c) Write applications of superconductivity. [4]

  1. (a) Explain the need of a cavity resonator in a laser. [6]

(b) With the help of suitable diagrams, explain the principle, construction and working of a Ruby laser. [10]

  1. (a) Distinguish between light propagation in

i. step index and ii. graded index optical fibres. [6] (b) Discuss the various advantages of communication with optical fibres over the conventional coaxial cables. [6] (c) Calculate the refractive indices of core and cladding of an optical fibre with a numerical aperture of 0.33 and their fractional difference of refractive indices being 0.02. [4]