PPT Slide

50

• When metals conduct at ordinary temperatures, electron flow is  restricted by collisions with atoms vibrating in their lattice sites.

• The restricted flow causes resistive heating resulting in a loss of  energy.

• Another type of electrical conductivity, superconductivity, has  been observed in some metals by cooling them to near absolute zero.

• Superconducting metals conduct current without observable energy  loss.

• In 1986, new ceramic oxides were prepared  that superconduct near the boiling point of  liquid nitrogen (77 K).

Levitation of a magnet with YBa 2Cu 3O 7 at 77K.

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