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ECE :: Materials and Components

  1. When an electron moves at velocity v in combined electric and magnetic fields E and H, the Lorentz force F is F = - e(E + v x B).

  2. A.
    True
    B.
    False

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  3. A parallel plate capacitor has area of plate equal to 1 m and distance between plates is also 1 m2. The lossy dielectric has a complex dielectric constant ∈r = ∈'r - j"r. If the capacitor is represented by R and C is parallel, then

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  5. When Schrodinger equation is applied to the motion of electron in the field of protons, the physically acceptable solutions for the wave function exist for quantum number which are

  6. A.
    2
    B.
    3
    C.
    4
    D.
    5

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  7. For dielectrics in alternating field, polarizability ae is a complex quantity. The imaginary part of ae is zero for

  8. A.
    ω = 0
    B.
    ω → ∞
    C.
    ω = 0 and ω → ∞
    D.
    ω = natural frequency ω0

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  9. In the wave mechanical theory, the maximum of the charge distribution in the ground state occurs for a distance from the nucleus equal to

  10. A.
    first Bohr radius
    B.
    second Bohr radius
    C.
    third Bohr radius
    D.
    either first or second Bohr radius

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  11. Hysteresis curve is associated with motion of domain walls.

  12. A.
    True
    B.
    False

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  13. The number of protons in germanium atom is

  14. A.
    4
    B.
    16
    C.
    28
    D.
    32

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  15. Sulphur hexafluoride is used in

  16. A.
    transformers
    B.
    generators
    C.
    relays
    D.
    circuit breakers

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  17. The number of valence electrons in trivalent impurity is

  18. A.
    5
    B.
    4
    C.
    3
    D.
    1

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  19. The v-i characteristic shown in the given figure is for

  20. A.
    thermistor
    B.
    photoconductor
    C.
    varistor
    D.
    none of the above

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