The electrical resistance of a metal or alloy is a function of temperature, decreasing as the temperature falls & tending to a constant low value at ‘absolute zero’ or 0°K or -273°C. It is found that for certain metal and alloys (e.g. lead, vanadium, tin) the electrical resistivity drops suddenly to zero, in the neighborhoods of a few degrees above absolute zero. This phenomenon is known as superconductivity.

Application

1. Large Scale Applications:

Transmission of Power:

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One can have cable made with this material which can be cooledby liquid N; to carry large powers to distant areas thus saving 20-30% power which is lost in convertiaval system of transmission.

Storage of Energy:

Superconductor can be wound into a large solenoid with zero resistance, the current flowing in this solenoid would not dissipate, it would continue to flow endlessly, so we can generate power & put it in such a reservoir of superconducting magnet of large size so that when required it can be tapped of from this magnet and used.

Large superconducting magnets are used for nuclear fusion experiments, for making high power accelerators & in NMR technology especially for medical diagnosis.

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Superconductor would make it possible to have trains running at a very high speed (on magnetic cushions).

2. Small Scale Application:

They include magnetic shielding devices, medical imaging systems, superconducting quantum interference devices (SQUIDS), infra red sensors, analog signal processing devices, and microwave devices.