Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

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Questions

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!

  1. How does the resistance vary with temperature in a perfect superconductor?

    a The resistance falls continuously as the temperature approaches absolute zero.
    b The resistance initially falls but passes through a minimum before rising as the temperature approaches absolute zero.
    c The resistance initially falls before discontinuously dropping to zero at a temperature above absolute zero.
    d The resistance falls continuously down to a limiting value as the temperature approaches zero.

  2. Which property characterises superconductivity along with zero electrical resistance?

    a Perfect Ferromagnetism
    b Perfect Paramagnetism
    c Perfect Diamagnetism
    d The expulsion of any externally applied magnetic field.

  3. What carries the current in a superconductor once the electric field is removed?

    a Cooper pairs
    b Free electrons
    c Bound protons

  4. What causes electrons in a Cooper pair to be bound together in a conventional superconductor such as Nb or Sn ?

    a A coulombic interaction between the electrons
    b An interaction between electrons and the vibrations of the lattice
    c An interaction between electrons and the external magnetic field

  5. How does an externally applied magnetic field interact with a type II superconductor?

    a The applied magnetic field is fully expelled by the surface screening currents.
    b The applied magnetic field penetrates the material evenly
    c The applied magnetic field penetrates the material in 'bundles' which are surrounded by screening supercurrents.