Materials And Components MCQ Questions & Answers

81

Match List-I with List-II and select the correct answer using the options given below:

List-I (Material/Characteristics)	List-II (Superconductor kind)
a. Incomplete Meissner's effect, high critical field and transition temperature. Absence of Silsbee's rule	1. Hard superconductor
b. Meissner's effect and Silsbee's rule	2. Soft superconductor
c. Amorphous thin films of Be, Bi and Fi	3. Superconductor

A) a-1, b-3, c-2 B) a-1, b-2, c-3 C) a-3, b-2, c-1 D) a-3, b-1, c-2

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Answer & Solution

Answer: Option A

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82

Total number of crystal system is

A) 3 B) 7 C) 12 D) 16

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Answer & Solution

Answer: Option B

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83

When copper is added to silver in small quantity so as to form an alloy, the resistivity of such an alloy is

A) equal to the resistivity of copper B) equal to the resistivity of silver C) greater than the resistivity of copper D) in between the resistivity of silver and copper

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Answer & Solution

Answer: Option C

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84

The relative permeability is less than 1 in

A) ferromagnetic materials B) diamagnetic materials C) paramagnetic materials D) ferrites

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Answer & Solution

Answer: Option B

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85

The outermost electronic configuration a cobalt atom is 3d⁷4s². Its magnetic moment is-

A) 9 Bohr magnetrons B) 7 Bohr magnetrons C) 5 Bohr magnetrons D) 3 Bohr magnetrons

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Answer & Solution

Answer: Option D

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86

The critical stress σ_c for crack propagation in a brittle material, using the principles of fracture mechanics is

A) $${\left( {\frac{{2E{\gamma _s}}}{{2\pi \alpha }}} \right)^{\frac{1}{2}}}$$ B) $${\left( {\frac{{3E{\gamma _s}}}{{2\pi \alpha }}} \right)^{\frac{1}{2}}}$$ C) $${\left( {\frac{{2E{\gamma _s}}}{{\pi \alpha }}} \right)^{\frac{1}{2}}}$$ D) $${\left( {\frac{{3E{\gamma _s}}}{{\pi \alpha }}} \right)^{\frac{1}{2}}}$$

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Answer & Solution

Answer: Option C

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87

The wavelength of light emitted by a GaAs laser is 8670 × 10^-10 m. Given Planck's constant = 6.6256 × 10^-34 Js, velocity of light = 2.998 × 10⁸ ms^-1 and 1eV = 1.602 × 10^-19 J, the energy gap in GaAs is

A) 0.18 eV B) 0.7 eV C) 1.43 eV D) 2.39 eV

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Answer & Solution

Answer: Option C

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88

Blood flow can be measured using the electromagnetic principle because blood has a high

A) magnetic induction B) electrical resistivity C) electrical conductivity D) impedance

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Answer & Solution

Answer: Option C

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89

n - type silicon is obtained by doping silicon with

A) Germanium B) Aluminum C) Boron D) Phosphorus

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Answer & Solution

Answer: Option D

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90

The value of critical current density in a superconductor depends upon
1. Temperature
2. Magnetic field strength
3. Penetration depth

A) 1, 2 and 3 B) 1 and 3 only C) 2 and 3 only D) 1 and 2 only

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Answer & Solution

Answer: Option D

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Materials And Components MCQ Questions & Answers | ECE