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ECE :: Materials and Components

  1. From a homogeneous and isotropic dielectric material of dielectric constant ∈r, a small volume element is taken out creating a cavity. The field can be kept homogeneous if Di. (i.e., electric flux density inside the cavity) and D0 (i.e., electric flux density outside the cavity) are such that

  2. A.
    D0 = Di
    B.
    C.
    D.
    either (a) or (b)

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  3. An electrolytic capacitor can be used for

  4. A.
    ac only
    B.
    dc only
    C.
    both ac and dc
    D.
    high frequency ac

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  5. Figure shows a composite capacitor. If CA, CB, CC are the capacitances of capacitors A, B, C, the overall capacitance C is

  6. A.
    C = CA + CB + CC
    B.
    C = (CA + CB) CC
    C.
    C =
    D.
    C =

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  7. As regards ferromagnetic Curie temperature Qf and paramagnetic curie temperature θ

  8. A.
    Qf > θ
    B.
    θ > Qf
    C.
    θ equal to or less than Qf
    D.
    θ may be equal to less than or more Qf

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  9. If there are no permanent dipoles in a dielectric material, the dielectric constant is independent of temperature.

  10. A.
    True
    B.
    False

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  11. Assertion (A): Magnetic susceptibility of copper is -0.5 x 10-5.

    Reason (R): Copper is diamagnetic material.

  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 electron shell corresponding to principal quantum number n can contain a maximum of

  14. A.
    n2 electrons
    B.
    2n2 electrons
    C.
    2n electron
    D.
    n3 electron

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  15. A sheet of bakelite is inserted between the plates of an air capacitor. The capacitance will

  16. A.
    increase
    B.
    decrease
    C.
    remain the same
    D.
    may increase or decrease

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  17. The spin angular momentum along a given direction is either or .

  18. A.
    True
    B.
    False

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  19. Lines of magnetic field cannot intersect.

  20. A.
    True
    B.
    False

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