This set of Materials Science Multiple Choice Questions & Answers (MCQs) focuses on “Microscopic Examination”.
1. Calculate the average number of grains per square inch at a magnification of 100. Consider grain number is 40?
Explanation: Grain size number and average number of grains per square inch are related as,
N = 2n-1
N = 240-1
N = 5.49*1011.
2. For grain size number (ASTM) which of the following is true?
a) Size of grains with grain size no 8 will be more than that of grain size no 5
b) Size of grains with grain size no 6 will be more than that of grain size no 7
c) Size of grains with grain size no 6 will be more than that of grain size no 2
d) Size of grains with grain size no 14 will be more than that of grain size no 15
Explanation: Grain size number ranges from 1 to 10. Larger the no of grain size smaller are the grains.
3. Which of the following is not an important application of microstructure examination?
a) To ensure that the associations between the properties and structure (and defects) are properly understood
b) To predict the properties of materials once these relationships have been established
c) To design alloys with new property combinations
d) To ascertain the mode of chemical fracture
Explanation: First three are the applications of microstructure examination while in case of fourth, to ascertain mode of physical fracture is the application instead of chemical fracture.
4. Which of the following microscope are not used for microscopy?
d) Scanning probe
Explanation: Ultrasonic microscope has a very high resolution of the range of 300*300 pixels which is not desired for micro compounds. It is useful for compounds having very small size range.
5. Which technique is used to determine the grain size of polycrystalline materials?
a) Photo micrographic technique
b) Positron annihilation technique
c) Measuring resistivity after quenching
d) Thermal imaging
Explanation: Positron annihilation technique, Measuring resistivity after quenching and Thermal imaging this technique is used to measure the concentration of vacancy to determine the activation energy for its formation.
6. Which type of microscopic technique has been developed that generate topographical maps representing the surface features and characteristics of the specimen?
d) Scanning probe
Explanation: More recent scanning probe microscopic techniques have been developed that generate topographical maps representing the surface features and characteristics of the specimen. Examinations on the atomic and molecular levels are possible using these techniques.
7. Which of the following method is commonly used to determine grain size?
b) Standard comparison charts
d) Electrical conductivity
Explanation: Intercept and standard comparison charts are commonly used in grain size determination.
8. What is the range of grain size number in case of ASTM?
a) 1 to 10
b) 1 to 100
c) 1 to 1000
d) 1 to 10000
Explanation: Grain size number ranges from 1 to 10. Size of grain varies inversely with grain size number. Example if grain size number is 10 then the size of grain will be smallest and for 1 it will be largest.
9. What is the full form of ASTM?
a) American society for testing and materials
b) African society for testing and materials
c) American society for torque and momentum forces
d) American society for tensile motion forces
Explanation: The American Society for Testing and Materials (ASTM) has prepared several standard comparison charts, all having different average grain sizes.
10. Which of the following is not the structural characteristic of a polycrystalline specimen?
b) Average size
Explanation: Shape, Average size and Diameter are the structural characteristics of polycrystalline specimen while reactivity is the chemical property.
Sanfoundry Global Education & Learning Series – Materials Science.
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