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MAP821S - MATERIALS PHYSICS - 2ND OPP - JAN 2023 |
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n Am I BI A u n IVE RS ITY
OF SCIEnCE Ano TECHnOLOGY
FACULTY OF HEALTH, NATURAL RESOURCES AND APPLIED SCIENCES
DEPARTMENT OF NATURAL AND APPLIED SCIENCES
QUALIFICATION: BACHELOROF SCIENCEHONOURS
QUALIFICATION CODE: 08BOSH
LEVEL: 8
COURSE CODE: MAP/821S
COURSE NAME: MATERIALS PHYSICS
SESSION: JANUARY 2023
DURATION: 3 HOURS
PAPER: THEORY
MARKS: 100
SUPPLEMENTARY/SECONODPPORTUNITYEXAMINATIONQUESTIONPAPER
EXAMINER{S) Prof Dipti R. Sahu
MODERATOR: Dr Zivayi Chiguvare
INSTRUCTIONS
1. Answer all five questions.
2. Write clearly and neatly.
3. Number the answers clearly.
PERMISSIBLEMATERIALS
Non-programmable Calculators
THIS QUESTION PAPER CONSISTS OF 3 PAGES (Including this front page)
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Question 1
[10]
1.1 What is hardness? Mention any two types of hardness measurements?
(2)
1.2 Consider a cylindrical nickel wire 2.0 mm in diameter and 3 x 104 mm long. Calculate its (4)
elongation when a load of 300 N is applied. Assume that the deformation is totally elastic
for Ni, E = 207 GPa.
1.3
What is the classification of the engineering materials? Explain the materials in brief. (4)
Question 2
[10]
2.1 Explain photoconductivity process in a semiconductor.
(2)
2.2
Determine the penetration depth of the primary electrons in ZnS for an incident
(4)
beam of energy of 10 keV. Given that K = 1.2 x10-4 and b =0.0175
2.3 What is the meaning of optical materials? How you classify optical materials into
different categories, Mention the categories and explain.
(4)
Question 3
[10]
3.1 The thermal conductivity of a plain carbon steel is greater than for a stainless steel.
Why is this so?
(2)
3.2 A cuboid room is perfectly isolated on all sides, except one. This side, 6m long and 2m
high, is 25cm thick and shows a heat conductivity of0.8W/(Km). The wall has no
windows. The temperature of the inner wall surface is l0°C, the temperature of the
outer wall surface is -l0°C. Calculate the heat flow through the wall?
(4)
3.3 What is thermal shock resistance? Thermal shock behaviour is affected by which factors? (4)
Question 4
[10]
4.1 What do you mean by dielectric constant of a materials
(2)
4.2 A solid contains 5 x 1028 atoms/m 3 each with a polarisability of 2xl0--4° F m2•
Assuming that the internal field is given by Lorentz formula. Calculate the ratio of
internal field to the external field. Ea= 8.854 x 10-12 Fm-1.
(4)
4.3 What is Piezoelectricity? Give an example of piezoelectric materials and its applications. (4)
Question 5
[10]
5.1
Explain the terms polymer and monomer
(2)
5.2 How are Polymer classified based on structure? Give representation of each polymer (4)
5.3 What are thermosetting and thermoplastic polymer? Give example for each.
(4)
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Question 6
[10)
6.1 Mention what is the primary mineral in glass products? What is fused silica glass?
(2)
6.2 Calculate the density in grams per cubic centimetre of SrSnO3ceramic, which has the (4)
perovskite structure. Ionic radii are Sr2+= 0.127 nm, Sn4+= 0.074 nm, and 0 2- = 0.132 nm.
Assume the lattice constant a= 2(rsn4++ r02-)
6.3 What are some of the properties common to most ceramic materials? Distinguish
(4)
between traditional and engineering ceramic materials and give examples of each.
Question 7
[10)
7.1 What is Domain wall energy (or) Bloch wall energy?
(2)
7.2 The saturation magnetic induction of Nickel is 0.65 Wb m-2• If the density of Nickel is
8906 kg m-3and its atomic weight is 58.7, calculate the magnetic moment of the
Nickel atom in Bohr magnetron.
(4)
7.3 Explain different types of magnetic materials in brief?
(4)
Question 8
[10)
8.1 What is a composite ?
(2)
8.2 A continuous and aligned glass fiber-reinforced composite consists of 40 vol% of
glass fibers having a modulus of elasticity of 69 GPa and 60 vol% of a polyester
resin that, when hardened, displays a modulus of 3.4 GPa. Compute the modulus
of elasticity of this composite in the longitudinal direction
(4)
8.3 What are the functions of a reinforcement in a composite?
(4)
Question 9
[10)
9.1 Justify, is compound semiconductor can be an intrinsic semiconductor?
(2)
9.2 In a P-type Si sample the hole concentration is 2.25 x 1015/cm3. The intrinsic
carrier Concentration is 1.5 x 1010/cm 3. Calculate the electron concentration
(4)
9.3 Compare silicon and gallium arsenide semiconductors relative to properties and
applications?
(4)
Question 10
[10)
10.1 What do you mean by linear and planar densities
(2)
10.2 Calculate the equilibrium number of vacancies per cubic meter for copper at 1000°c.
The energy for vacancy formation is 0.9 eV/atom: the atomic weight and density
(at 1000°() for copper are 63.5 g/mol and 8.4 g/cm 3, respectively
(4)
10.3 Explain the difference in electrical conductivity for metals, semiconductors, and
insulators in terms of their electron energy band structures.
(4)
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