06 June 2012

Solid State Physics - Lattice Imperfections - Quiz

1. Point defects are
   a) vacancies, dislocations, impurities, phonons
   b) grain boundaries, voids
   c) stacking faults, impurities
   d) vacancies, impurities, Frenkel defects, interstitials

2. The energy of formation of a schottky defect
     a) depends on temperature
     b) is independent of temperature
     c) is an inverse function of temperature
     d) is a function of the logarithm of defect concentration

3. Any metal crystal in thermal equilibrium contains
    a) Schotlky and Frenkel defects, unavoidable impurities, interstitias
    b) Only Scholtlky defects and Frenkel defects
    c) Only vacancies
    d) Only Frenkel defects and impurities

4. The defects that arise in a crystal as requirement of thermodynamic equilibrium are
    a) phonons
    b) excitons
    c) point defects
    d) dislocations

5. In close packed structures
   a) Frenkel defects are the dominating defects
   b) dislocations are the dominant defects
   c) Schotlky defects are the dominant defects
   d) Schotlky defect concentration will be far less than the Frenkel defect contration

6. In alkali halides
    a) Frenkal defects are the dominating defects
    b) Schotlky defects are the dominating defects
    c) dislocations are the dominating defects
    d) vacancy pairs are the dominating defects

7. In silver halides
    a) no defects can be present
    b) Schotlky defects are dominating defects
    c) Interstials are the dominating defects
    d) Frenkel defects are the dominating defects

8. A grain boundary is
    a) a pair of edge dislocations of opposite nature
    b) an irregular sequence of layers of atoms
    c) a series of closely spaced dislocations
    d) a three dimensional defect

9. A dislocation is
   a) always under shear
   b) a point defect
   c) a two dimensional defect
   d) under compression

10. A Schotlky defect in an ionic crystal is
     a) a pair of negative ion vacancies
     b) a pair of positive ion vacancies
     c) a pair of negative ion vacancy and positive ion vacancy
     d) a pair of vacancy and an ion in the lattice