Engineering Physics of Materials

Part A

1. In a metal, if the temperature is increased, then resistivity

A) Increases                B) Decreases                           C) Remains same          D) None of these

2. The Fermi factor for E = E_F at any temperature is

A) 1                             B) ½                                        C) 0                               D) 2

3. Which of the following is not a laser property?

A) Highly monochromatic                                          B) High directionality

C) Very narrow bandwidth                                       D) Highly divergent

4. Which one of the following is an attenuation mechanism?

A) Absorption                                                             B) Scattering

C) Microscopic and macroscopic bending                  D) All of these                       

5. In ferromagnetic materials, the field required to reduce the flux density to zero is called

A) Coercivity              B) Remnance                          C) Saturation               D) Susceptibility

6. According to Meissner effect, material in superconducting state is,

A) Paramagnetic                                                         B) Diamagnetic                      

C) Ferromagnetic                                                        D) Anti-ferromagnetic

7. The miller indices of the plane parallel to x axis and y axis are 

A) (100)                      B) (010)                                   C) (001)                       D) (111)

8. Which of the following is not a part of Bragg’s spectrometer?

A) X-ray tube                                                              B) Crystal table                      

C) Ionization chamber                                                            D) Barometer

9. Decomposition of materials at high temperature is called

A) Carbon arc discharge                                             B) Sol-Gel method

C) Pyrolysis                                                                 D) Milling.

10. Which one of the following is a structure of CNT?

A) Armchair                                                                B) Zig-zag

C) Chiral                                                                     D) All of these

                                                                                                            (1Mark × 10 =10 Marks)

Part B

Module 1

1 (a) Write a note on merits of quantum free electron theory.                                    (4 Marks)

(b) Find the temperature at which there is 1 % probability that a state with an energy 0.5eV above Fermi energy will be occupied.                                                                (4 Marks)

(OR)

2 (a) Explain failure of classical free electron theory.                                     (4 Marks)

(b) A uniform silver wire has resistivity 1.54×10^-8 ohm-m at room temperature for an electric field 2 v/m.  Calculate relaxation time and drift velocity of the electrons, assuming that there are 5.8×10²² conduction electrons per cm³ of the material.                                        (4 Marks)

Module 2

3 (a) Explain the different types of optical fibers.                                                      (4 Marks)

(b) The average output power of laser source emitting a laser beam of wavelength 632.8nm is 5 mW. Find the number of photons emitted per second by the laser source.               (4 Marks)

(OR)

4 (a) Obtain an expression for energy density of radiation under equilibrium condition in terms of Einstein co-efficients.                                                                                            (5 Marks)

(b) The refractive indices of core and cladding are 1.41 and 1.40 respectively in an optical fiber. Find the numerical aperture.                                                                                              (3 Marks)

Module 3

5 (a) Write a note on classification of magnetic materials.                                         (3 Marks)

(b) Explain BCS theory of superconductivity.                                                           (5 Marks)

(OR)

6 (a) Define superconductivity and explain Type I and Type II superconductors.    (5 Marks)

(b) A magnetic material has a magnetization of 2300 A/m and produces a flux density of 0.00314 wb/m². Calculate magnetizing force and relative permeability of the material. (3 Marks)

Module 4

7 (a) Derive expression for interplanar spacing in terms of Miller indices.                 (4 Marks)

(b) The minimum order of Bragg’s reflection occurs at an angle 20⁰ in the plane [212]. Find the wavelength of X-ray if lattice constant is 3.615 Å.                                                  (4 Marks)

(OR)

8 (a) Define coordination number and packing factor. Calculate the packing factor for sc, fcc and bcc structures.                                                                                                             (8 Marks)

Module 5

9 (a) Explain Ball milling method.                                                                              (4 Marks)

(b) Write a note on different properties of CNT.                                                       (4 Marks)

(OR)

10 (a) Write a note on shapes of nanomaterials.                                                         (3 Marks)

(b) Explain Carbon arc discharge method for the synthesis of CNT.                         (5 Marks)