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ECE :: Materials and Components

Materials and Components - Section 1
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Materials and Components - Section 3
Materials and Components - Section 4
Materials and Components - Section 5
Materials and Components - Section 6
Materials and Components - Section 7
Materials and Components - Section 8
Materials and Components - Section 9

  1. The temperature at which some materials become superconductors is called

    2. A.
    Transition temperature
    B.
    Curie temperature
    C.
    Neel temperature
    D.
    Onnes temperature

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  2. The quantum numbers associated with electron motion are designed as

    3. A.
    a, b, c
    B.
    h, k, l
    C.
    n, m, l
    D.
    h, n, l

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  3. The carrier mobility in a semiconductor is 0.4 m2/Vs. Its diffusion constant at 300 K will be (in m2/s)

    4. A.
    0.40
    B.
    0.16
    C.
    0.04
    D.
    0.01

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  4. Which of these has lowest dielectric strength?

    5. A.
    Dry air
    B.
    Wet air
    C.
    Cotton
    D.
    Paper

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  5. As per Curie-Weiss law, the magnetic susceptibility of a material varies as

    6. A.
    T-2
    B.
    C.
    T
    D.
    T2

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  6. The amount of time between the creation and recombination of a free electron and hole is called

    7. A.
    relaxation time
    B.
    life time
    C.
    lorentz time
    D.
    collision time

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  7. A photoconductor is a

    8. A.
    conductor
    B.
    semiconductor
    C.
    insulator
    D.
    superconductor

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  8. Assertion (A): Both sodium and ferrous are ferromagnetic.

    Reason (R): Both sodium and ferrous have body centred cubic structure.

    9. A.
    Both A and R are true and R is correct explanation of A
    B.
    Both A and R are true but R is not correct explanation of A
    C.
    A is true but R is false
    D.
    A is false but R is true

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  9. For iron, the ferromagnetic Curie temperature is

    10. A.
    about 20 K
    B.
    about 100°C
    C.
    about -20°C
    D.
    about 1000 K

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  10. As regards dielectric constant εr

    11. A.
    the units are farads/m
    B.
    the units are newton/coulomb
    C.
    it is dimensionless
    D.
    the units are farads

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