This set of Materials Science Multiple Choice Questions & Answers (MCQs) focuses on “Linear Defects – 1”.
1. A dissolution in which an extra portion of a plane of atoms or a half plane terminates within a crystal is called as ________
a) Edge dislocation
b) Mixed dislocation
c) Interfacial dislocation
d) Screw dislocation
Explanation: Screw dislocation is formed by a shear stress that is applied to produce the distortion. Mixed Dislocations are dislocations found in crystalline materials are probably neither pure edge nor pure screw, but exhibit components of both types.
2. The magnitude and direction of lattice distortion are expressed in terms of which vector?
a) Dislocation vector
b) Screw vector
c) Edge vector
d) Burger vector
Explanation: Burger vector is used to denote magnitude and direction. In physics, the Burgers vector, named after Dutch physicist Jan Burgers, is a vector, often denoted as b, that represents the magnitude and direction of the lattice distortion resulting from a dislocation in a crystal lattice.
3. What is the relative orientation of dislocation lines for edge dislocation?
d) Both parallel and perpendicular
Explanation: For edge dislocation the nature of dislocation line is perpendicular.
4. What type of direction will the burger vector of dislocation for a metallic material show?
a) Closed-packed crystallographic direction
b) Rounded-packed crystallographic direction
c) Open-packed crystallographic direction
d) Parallel-packed crystallographic direction
Explanation: For a metal being solid, its atoms are closely packed and also metals are crystalline in nature so the direction shown by the vector will be closed packed crystalline direction.
5. Which technique is used to observe dislocation?
a) Positron annihilation technique
b) Thermal imaging
c) Thermal expansion measurements
d) Electron-microscope technique
Explanation: This type of microscope consists of a high magnification transmission electron micrograph in which dark lines represent dislocation.
6. Path of screw dislocation is in the form of _______
c) Spiral or helical
Explanation: Ramp that is traced around dislocation line is spiral or helical that’s the reason it is called screw dislocation.
7. Which type of deformation occurs due to dislocation?
a) Slip plastic deformation
b) Elastic deformation
c) It does not show deformation
d) Slip elastic deformation
Explanation: Dislocation involves sliding of crystal blocks over one another along the definite crystallographic plane which results in a slip.
8. Which type of stress is involved in the motion of screw dislocation?
a) Tensile stress
b) Shear stress
c) Compressive stress
d) Does not involve stress
Explanation: If shear stress is increased in screw dislocation it results in a slip of one layer over other which ultimately leads to deformation.
9. Which type(s) of dislocation are included in mixed dislocation?
a) Only Edge dislocation
b) Only shear dislocation
c) Only screw dislocation
d) Both edge and screw dislocation
Explanation: Mixed dislocation is a combination of screw and edge dislocation. It does not consist of only pure edge or pure screw dislocation.
10. What is the mechanism in which edge dislocation move out of the slip is called _______
a) Climb dislocation
b) Screw dislocation
c) Shear dislocation
d) Slip dislocation
Explanation: In this type of dislocation edge moves perpendicular over its slip plane.
Sanfoundry Global Education & Learning Series – Materials Science.
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