Homework Answers
Physical Properties of Ceramics
- Electrical and thermal conductivities lower than for metals but the range of values is greater, so some ceramics are insulators while others are conductors.
- Melting temperature is higher than most metals (ceramics tend to decompose than melt)
- Most ceramics are lighter than metals but heavier than polymers.
- Thermal expansion - somewhat less than for metals, but effects are more damaging because of brittleness.
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Select all responses that are true for ceramics. Electrical conductivity of ceramics is generally...
(a) As the bond strength in a material increases we normally find that: the electrical conductivity...
(a) As the bond strength in a material increases we normally find that: the electrical conductivity decreases the electrical conductivity increases the melting point decreases the melting point increases The material becomes more metallic in character (b) In an intrinsic semiconductor: There are absolutely no impurities The electrical conductivity is only determined by thermal excitations The electrical conductivity is independent of the bandgap. There are equal numbers of free electrons and holes (Both electrons and holes will contribute significantly to...
(iv) Write down an expression for the electrical conductivity of a material and define all the...
(iv) Write down an expression for the electrical conductivity of a material and define all the variables in your equation. (2) (v) Now use your equation from (iv) and the sketches of band structure from (iii) to explain the differences in electrical conductivity between metals, semiconductors and insulators. (4)
Which statement is true? Select one: O a. The electrical conductivity of a semiconductor increases with...
Which statement is true? Select one: O a. The electrical conductivity of a semiconductor increases with temperature b. The resistivity of a semiconductor increases with temperature o c. Metals and semiconductors have similar electrical conducting properties O d. The electrical conductivity of a metal increases with temperature Save response Which statement is true about an XY2 lattice? Select one: O a. The unit cell contains twice as many X2n+ ions as Yn- b. The coordination environments of x2n+ and Yn-are...
Q21. Which one of the following statements about the ductility of metals is TRUE? A High ductility occurs in brittle materials B Ductility is the amount of deformation at the 0.2% proof stress C Duct...
Q21. Which one of the following statements about the ductility of metals is TRUE? A High ductility occurs in brittle materials B Ductility is the amount of deformation at the 0.2% proof stress C Ductility can be measured as % reduction in area from broken tensile samples D Ductility is deformation in the elastic region E Ductility is the change between upper and lower yield point in steels Q22. Which one of the following statements is TRUE about Charpy impact...
(1) (b) concrete, (c) polyethylene, or (d) water? 1.14 Copper is generally considered easy to weld...
(1) (b) concrete, (c) polyethylene, or (d) water? 1.14 Copper is generally considered easy to weld because of its high thermal conductivity: (a) true or (b) false? (1) 1,15 Which of the following properties or characteristics do not apply to metals (two correct answers): (a) good thermal conductivity, (b) high strength, (c) high electrical resistivity, (d) high stiffness, and (e) ionic bonding? 1.16 An alloy is a metal composed of two or more elements, at least one of which is...
1. All students: (a) By combining kinetic theory with classical mechanics, Drude was able to derive...
1. All students: (a) By combining kinetic theory with classical mechanics, Drude was able to derive a sensible equation for the electrical conductivity of metals. In the case of the thermal conductivity however, Drude's theory fails. Explain why (in bullet-point form). (b) The Fermi energy of copper is ~8 eV. What fraction of electrons are above the Fermi-level at room temperature? (c) Write down a general expression for the electron density in terms of the density of states and the...
1. Ferrous metals include which of the following A Aluminum B. Copper C Gold D. Steel...
1. Ferrous metals include which of the following A Aluminum B. Copper C Gold D. Steel 2. The two categories of metals that are based onion (Fe) are A Aluminum Alloy & Castle B. Chromium & Nickel C. Manganese & Vanadium D. Cast Iron & Steel 3. Aluminum Alloy, Nickel Alloy, Zinc Alloy, and Titanium Alloy are cumples of A Nonferrous Metals B.Ceramics C Superllos D. Carmets 4. In the heating of most metal alloys melting begins at a certain...
please answer all of the questions below: .Stay Home- Mobily 8:23 AM 82% Question 1 Strong...
please answer all of the questions below:
.Stay Home- Mobily 8:23 AM 82% Question 1 Strong and ductile materials Metals Polymers Ceramics © Ceramics Semiconductors Question 2 Presently most used metal in the world Gold Silver o Aluminium Steel Question 3 Question 3 First metal known to be used by man Iron ( 1 ) Bronze Aluminium Silver Question Question 4 Pick the composite from the list Cement Nylon CFRP Steel Question 5 First material known to be used by...
Which of the following is the best explanation of nudeation? Select one: a. all of the...
Which of the following is the best explanation of nudeation? Select one: a. all of the above are true b. it can be initiated by the addition of a seed crystal to a saturated solution O c. it is the first step in the process of crystallization d. it can be initiated by providing nucleation sites - tiny crevices in a surface When the melting point of a mixture is measured, what is generally true about the results? estion Select...
1. Select all true statements about plastic machining/ fabrication. A. metal inserts are chemically bonded in...
1. Select all true statements about plastic machining/ fabrication. A. metal inserts are chemically bonded in plastic parts B. large flat surfaces are generally preferred due to plastic's elastic modulus C. curing time is determined from the thinnest wall section D. raised letters on a plastic part incur less mold expense than depressed letters E. parting lines should be placed along plastic part corners and edges 2. Select benefits of fabricating with plastics, ceramics, and composites. A. one process can...
(a) As the bond strength in a material increases we normally find that: the electrical conductivity decreases the electrical conductivity increases the melting point decreases the melting point increases The material becomes more metallic in character (b) In an intrinsic semiconductor: There are absolutely no impurities The electrical conductivity is only determined by thermal excitations The electrical conductivity is independent of the bandgap. There are equal numbers of free electrons and holes (Both electrons and holes will contribute significantly to...
(iv) Write down an expression for the electrical conductivity of a material and define all the variables in your equation. (2) (v) Now use your equation from (iv) and the sketches of band structure from (iii) to explain the differences in electrical conductivity between metals, semiconductors and insulators. (4)
Which statement is true? Select one: O a. The electrical conductivity of a semiconductor increases with temperature b. The resistivity of a semiconductor increases with temperature o c. Metals and semiconductors have similar electrical conducting properties O d. The electrical conductivity of a metal increases with temperature Save response Which statement is true about an XY2 lattice? Select one: O a. The unit cell contains twice as many X2n+ ions as Yn- b. The coordination environments of x2n+ and Yn-are...
Q21. Which one of the following statements about the ductility of metals is TRUE? A High ductility occurs in brittle materials B Ductility is the amount of deformation at the 0.2% proof stress C Ductility can be measured as % reduction in area from broken tensile samples D Ductility is deformation in the elastic region E Ductility is the change between upper and lower yield point in steels Q22. Which one of the following statements is TRUE about Charpy impact...
(1) (b) concrete, (c) polyethylene, or (d) water? 1.14 Copper is generally considered easy to weld because of its high thermal conductivity: (a) true or (b) false? (1) 1,15 Which of the following properties or characteristics do not apply to metals (two correct answers): (a) good thermal conductivity, (b) high strength, (c) high electrical resistivity, (d) high stiffness, and (e) ionic bonding? 1.16 An alloy is a metal composed of two or more elements, at least one of which is...
1. All students: (a) By combining kinetic theory with classical mechanics, Drude was able to derive a sensible equation for the electrical conductivity of metals. In the case of the thermal conductivity however, Drude's theory fails. Explain why (in bullet-point form). (b) The Fermi energy of copper is ~8 eV. What fraction of electrons are above the Fermi-level at room temperature? (c) Write down a general expression for the electron density in terms of the density of states and the...
1. Ferrous metals include which of the following A Aluminum B. Copper C Gold D. Steel 2. The two categories of metals that are based onion (Fe) are A Aluminum Alloy & Castle B. Chromium & Nickel C. Manganese & Vanadium D. Cast Iron & Steel 3. Aluminum Alloy, Nickel Alloy, Zinc Alloy, and Titanium Alloy are cumples of A Nonferrous Metals B.Ceramics C Superllos D. Carmets 4. In the heating of most metal alloys melting begins at a certain...
please answer all of the questions below:
.Stay Home- Mobily 8:23 AM 82% Question 1 Strong and ductile materials Metals Polymers Ceramics © Ceramics Semiconductors Question 2 Presently most used metal in the world Gold Silver o Aluminium Steel Question 3 Question 3 First metal known to be used by man Iron ( 1 ) Bronze Aluminium Silver Question Question 4 Pick the composite from the list Cement Nylon CFRP Steel Question 5 First material known to be used by...
Which of the following is the best explanation of nudeation? Select one: a. all of the above are true b. it can be initiated by the addition of a seed crystal to a saturated solution O c. it is the first step in the process of crystallization d. it can be initiated by providing nucleation sites - tiny crevices in a surface When the melting point of a mixture is measured, what is generally true about the results? estion Select...
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