GATE XE Properties and Applications of Materials PYQs & Answers — Page 8

Questions 71–79 of 79. Imported answers require independent review unless marked reviewed.

Ceramic materials fail at stresses much lower than their theoretical strength due to

Your answerChoose one option.

Presence of dislocations

High elastic modulus

Presence of voids

Anisotropy in crystal structure

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Which of the following treatment(s) can increase the electrical conductivity of silicon

(i) Heating (ii) Doping with arsenic (iii) Doping with aluminium (iv) Exposure to light

Your answerChoose one option.

Only (i)

Only (i) and (ii)

Only (i), (ii) and (iv)

All (i), (ii), (iii) and (iv)

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A continuous, aligned carbon fibre (CF) reinforced polymer composite with 30 vol% of CF and rest resin was designed for a specific application. The modulus of elasticity of CF is 17 GPa and that of the resin is 3.0 GPa. The modulus of elasticity for this composite in the direction of fibre alignment is ............GPa.

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Match the composites in Column I with the most suitable application in Column II

Column I (P) Exfoliated silicates filled butyl rubber (Q) Fiber reinforced aluminium alloy (R) Silicon carbide whiskers reinforced alumina (S) Carbon particles reinforced plastic composites

Column II (1) Automobile pistons (2) Contact lenses (3) Ski boards (4) Tennis balls (5) Cutting tool inserts for machining

Your answerChoose one option.

P-4; Q-1; R-5; S-3

P-2; Q-3; R-4; S-5

P-3; Q-5; R-5; S-3

P-2; Q-1; R-3; S-5

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Which of the following statement(s) is/are true

(i) All piezoelectric materials are necessarily ferroelectric (ii) All ferroelectric materials are necessarily piezoelectric (iii) All pyroelectric materials are necessarily piezoelectric (iv) All pyroelectric materials are necessarily ferroelectric

Your answerChoose one option.

(i) and (ii)

(ii) and (iii)

(i) and (iv)

(ii) and (iv)

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A ceramic material with a critical flaw size of 30

m has fracture stress of 300 MPa. For the same material the fracture stress for a critical flaw size of 90

m will be ..............MPa.

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An inorganic material that is transparent under solar light appears coloured when doped with transition metal ions. The possible reason(s) for the colour is/are

(i) The electronic energy levels of the host material changes significantly by doping (ii) The doped element selectively absorbs certain wavelength of light other than the perceived color (iii) The doped element emits radiation of specific wavelength

Which of the above statement(s) is/are true?

Your answerChoose one option.

Only (i)

Both (i) and (ii)

Both (i) and (iii)

Both (ii) and (iii)

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Copper is an FCC metal with lattice parameter of 3.62 Å. Hall effect measurement shows electron mobility to be 3.2

. Electrical resistivity of copper is 1.7

Ωm. The average number of free electrons per atom in copper is ....................(Charge of an electron: 1.6

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Which of the following statement(s) is / are true regarding susceptibility of a material

(i) Magnetic susceptibility is positive for a diamagnetic material (ii) Magnetic susceptibility is negative for a diamagnetic material (iii) Magnetic susceptibility is negative for an antiferromagnetic material (iv) Magnetic susceptibility is positive for a paramagnetic material

Your answerChoose one option.

(ii) and (iv)

(i) and (iii)

(ii) and (iii)

(i) and (iv)

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GATE XE Properties and Applications of Materials PYQs

Question 39

Question 42

Question 44

Question 45

Question 49

Question 51

Question 52

Question 53

Question 55