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ECE :: Materials and Components

  1. A parallel plate capacitor having C = 200 x 10-12 F has loss dielectric having tan δ = 4 x 10-4. At an ac voltage of f = 106 Hz and peak value 2 V, the dielectric losses are

  2. A.
    10-8 W
    B.
    10-6 W
    C.
    10-4 W
    D.
    10-2 W

  3. In ferromagnetic materials, the orientation between neighbouring permanent dipoles is parallel.

  4. A.
    True
    B.
    False

  5. Resistivity of copper is lower than that of nickel. When a small percentage of copper is added to nickel, the resistivity

  6. A.
    increases
    B.
    decreases
    C.
    may increase or decrease
    D.
    remains the same

  7. Lines of magnetic field attract each other.

  8. A.
    True
    B.
    False

  9. The maximum temperature limit of class B insulation is

  10. A.
    90°C
    B.
    105°C
    C.
    120°C
    D.
    130°C

  11. Resistivity of metals consists of two parts, one part constant and the other temperature dependent.

  12. A.
    True
    B.
    False

  13. The number of valence electrons in germanium atom is

  14. A.
    4
    B.
    2
    C.
    1
    D.
    zero

  15. Assertion (A):0 has the dimensions of farad per meter.

    Reason (R): D = ∈0r E.

  16. 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

  17. When temperature is more than ferromagnetic curie temperature, the behaviour of a ferromagnetic material is similar to that of paramagnetic material.

  18. A.
    True
    B.
    False

  19. If ω0 is the angular frequency of rotation of electron in the absence of magnetic field, the angular frequency ω, when a magnetic field B is acting is ω ≅ ω0 + (e/2m)B.

  20. A.
    True
    B.
    False