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ECE :: Materials and Components

  1. The number of protons in a silicon atom are

  2. A.
    4
    B.
    8
    C.
    12
    D.
    14

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  3. The fact that domains exhibits spontaneous magnetisation is

  4. A.
    first hypothesis is of Curie
    B.
    second hypothesis is of Weiss
    C.
    Curie-Weiss law
    D.
    Boltzmann's statistics

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  5. Assertion (A): Hall effect is used to determine whether the semi- conductor is p or n type.

    Reason (R): Under the influence of field, holes and electrons move in opposite direction.

  6. 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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  7. The most important set of specifications of transformer oil include

  8. A.
    dielectric strength and viscosity
    B.
    dielectric strength and flash point
    C.
    viscosity and flash point
    D.
    flash point and viscosity

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  9. Nickel is a non-magnetic material.

  10. A.
    True
    B.
    False

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  11. With increase in temperature, the electrical conductivity would

  12. A.
    increase in metals as well as in intrinsic semiconductor
    B.
    increase in metals but decrease in intrinsic semiconductor
    C.
    decrease in metals but increase in intrinsic semiconductor
    D.
    decrease in metals as well as in intrinsic semiconductor

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  13. An electron for which l = 0 has zero orbital magnetic dipole moment.

  14. A.
    True
    B.
    False

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  15. The resistance of a metallic wire would

  16. A.
    increase as f increase
    B.
    decrease as f increase
    C.
    remains the same at all frequencies
    D.
    increase with f up to a certain frequency and then decrease

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  17. If a small amount of Cu is added to Ni conductor, then

  18. A.
    resistivity of Ni will decrease at all temperatures because Cu is a better conductor than Ni
    B.
    residual resistivity of Ni at low temperature will increase as Cu atoms act as defect centres
    C.
    resistivity of Ni will increase at all temperatures as Cu destroys the periodicity of Ni and acts as defects
    D.
    resistivity of Ni remains the same

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  19. When a dielectric material is subjected to alternating field, the absorption of energy by the material from the field is given by the imaginary part of polarizability.

  20. A.
    True
    B.
    False

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