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Engineering LibreTexts

28.12: Questions

  • Page ID
    32829
  • Quick questions

    You should be able to answer these questions without too much difficulty after studying this TLP. If not, then you should go through it again!

    What symmetry element must be absent for a material to be ferroelectric?

    a An axis of rotation.
    b A mirror plane.
    c A centre of symmetry.
    d An improper axis of rotation.
    Answer

    C

    Which of these is not a correct definition of polarisation?

    a The net dipole moment per unit volume.
    b The surface charge per unit area.
    c The movement of atoms giving rise to a dipole moment.
    d The net charge per dipole moment.
    Answer

    D

    Why are domains in crystals found in a manner such that their polarisation is coupled?

    a To reduce stray field energy.
    b To reduce dislocation strain energy.
    c To grow the crystal in a regular manner.
    d To give small grains.
    Answer

    A

    What is needed to make ferroelectric domains useful as a binary memory store?

    a Large domains.
    b A square hysteresis loop.
    c A large coercive field.
    d Small domains.
    Answer

    B

    If a ferroelectric, 50mm by 10 mm, has a measured surface charge of 2.5 x 10-4 Coulombs, and a lattice parameter of 5 x 10-10, what is the dipole moment in a single cubic unit cell?

    a 6.25 x 10-29
    b 6.25 x 10-35
    c 1.5625 x 10-35
    d 1.5625 x 10-29
    Answer

    A

    What field has to be applied to give a ferroelectric, with a square hysteresis loop, zero net polarisation?

    a The switching field.
    b The polarising field.
    c The coercive field.
    d The stray field.
    Answer

    C

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