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ECE :: Materials and Components

  1. Assertion (A): The angular momentum of an atom is due to three contributions viz. orbital, electron spin and nuclear spin.

    Reason (R): The nuclear spin magnetic moment is much more than electron spin magnetic moment.

  2. 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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  3. If WF is the Fermi level, then in a metal at T = 0

  4. A.
    all energy levels above WF filled, all those below WF are empty
    B.
    all energy levels below WF are filled, all those above WF are empty
    C.
    some energy levels, both below and above WF, are filled
    D.
    all energy levels below and above WF are filled

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  5. Silicon and germanium have diamond structure. The number of atoms in a volume equal to a3 where a is the edge of elementary cube are

  6. A.
    32
    B.
    16
    C.
    8
    D.
    4

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  7. If the radius of electron cloud around the nucleus of a rare gas atom is R, the electronic polarizability of the atom is porportional to

  8. A.
    R
    B.
    R2
    C.
    R3
    D.

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  9. By inserting a plate of dielectric between the plates of a parallel plate capacitor, the energy stored in the capacitor is increased five times. The dielectric constant of material is

  10. A.
    B.
    C.
    5
    D.
    25

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  11. Assertion (A): A capacitor with imperfect dielectric can be represented by a capacitance in parallel with resistance.

    Reason (R): For imperfect dielectrics, dielectric constant has real and imaginary parts.

  12. 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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  13. An atom of a rare gas is placed is an electric field E. Then

  14. A.
    the nucleus will be shifted in the direction of E by an amount which is proportional to E.
    B.
    the nucleus will not be shifted.
    C.
    the nucleus will be shifted in the direction of E by an amount which is independent of E.
    D.
    the nucleus will be shifted in a direction opposite to that of E.

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  15. In van der walls crystals, there exists a high degree of stability of the outer electron shell.

  16. A.
    True
    B.
    False

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  17. As per temperature limits, the number of categories of solid dielectrics are

  18. A.
    7
    B.
    6
    C.
    8
    D.
    5

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  19. At room temperature the number of conducting electrons in an intrinsic semiconductor

  20. A.
    is almost equal to the number of valence electrons
    B.
    is about half the number of valence electrons
    C.
    is small as compared to the number of valence electrons
    D.
    is a very small fraction of the number of valence electrons

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