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 King Saud University,   College of Science, Department of Physics  (Girls Section) Final Exam, 2nd Semester1428-29H, Saturday:  17/1/1429H (26/1/2008G),   Time: 8.00 am -11.00 am (3 hours),    Max. Marks: 20         Phys 474 Student’s Name:____________________________  Student’s No:____________           GroupNo. ---------------------------------------         Dr. --------------------------------------------- Answer all the 15 questions. Circle the choice (MCQs)/ Fill the gaps/ Write Drawing or derivations or definitions on the other side of the pages. Use separate sheets for rough work.

 Q.1 Relative density of packing in BCC lattice is: a)highly random b) highly periodic c)partly random and partly periodic d) None e) Q.2 A substance with FCC lattice has density 6250 kg/m3 and molecular weight 60.2. The lattice constant is: ( N= 6.602x 1026  ) a) 2 Å b) 2.75 Å c) 4 Å d) 8 Å Q.3 Given the lattice parameters a = b = 10.73 Å, c=15.2 Å; α = β = 90◦, γ = 120◦. The unit cell belongs to the system: a) Triclinic b) Hexagonal c) Orthorhombic d) monoclinic Q.4 Draw a (002) plane in cubic lattice. Q.5 The Bragg angle corresponding to a reflection for which ( h2 + k2 + l2 ) = 8 is found to be 14.35◦. X-rays of wavelength 0.71 Å are used. If there are two other reflections with smaller Bragg angles, the lattice constant and the crystal structure are:   -----------------            ---------------- Q.6 For a beryllium specimen, if the intensity of  transmitted beam is 70% that of initial beam, the thickness is: (Assume that µ = 3.56x106 m-1) a) 0.2 µm b) 0.7 µm c) 0.1 µm d) 3.5 µm Q.7 The energy associated with the beam used in electron microscopy compared with optical microscopy is: a) higher b) lower c) equal d) depends on the color of the beam.

 Q.8 Show the ratio of separation between lattice planes in SCC lattice  is :      d1: d2 : d3 = 1 : 1/√2 : 1/√3 [Consider the planes: (100), (101) and (111)]

 Q.9 Define the relative reduction in area of a material.

 Q.10 What is low carbon steel?

 Q.11 If a 10 mm ball with a load of 1000 kg produces an indentation of 2.44 mm, the Brinell hardness number is: a) 312.9 kg/mm2 b) 210.6 kg/mm2 c) 244 kg/mm2 d) 100 kg/mm2. Q.12 If the shear modulus for iron is 0.74 x1011 N/m2  and the Burgers vector is measured to be 3.4x 10-10 m, the self energy per unit length of edge  dislocation is: a) 5.4x 10-9 J/m b) 6.41x10-9 J/m c) 9.3x 10-10 J/m d) 12.82x10-9 J/m Q.13 The equilibrium concentration of vacancies in Nickel at 900 K is: ( The formation energy for Ni = 168 kJ mole-1, R= 8.314) a) 1.45x10-12 b) 5.59x10-30 c) 1.12x10-4 d) 1.78x10-10 Q.14 Stress- Strain curves are obtained through: a) hardness tests b) tensile tests c) scratch tests d) rebound tests Q.15 Density of a crystal remains same in the production     of -------------------- defects while the density of     crystal decreases in the production of ----------------- defects.

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