Thermistor and Super conductivity

# THERMISTOR : Thermal + Resistor

Thermistor is the heat sensitive resistor usually made of semiconducting material such that its resistance changes readily with the change in temperature.
      The resistance of thermistor decreases with rapidly increases of temperature. Its resistance may be in between 0.1 ohm to 10^7 ohm. Thermistor are made from oxide of semiconductor like : Nio, Mno, CoO.

* APPLICATION OF THERMISTOR:
1) They are used to measure very low temperature (≈10k) and to detect small change in temperature (0.001°C).

2) They are used as a voltage regulator

3) They are used as a safety device to protect the filament of picture tube of the TV.

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# SUPER CONDUCTIVITY :
Scientist kammerlingh onnes discovered that there are some substance whose resistivity decreases with decrease in temperature. At a specific low temperature  (Critical temperature) the resistivity become zero and the conductivity become infinity. This phenomena is called superconductivity and substance are called superconductor.

METALS                      Critical temperature

Mercury (Hg)                4.2 K
Lead (Pb)                        7.2 K
Neobium (Nb)                10 K

* Variation in the resistivity of super -
    Conductor with temperature.

* USES:
1) Superconductor are used for transmation of electric power.

2) They are used for making very strong electromagnet.

3) Superconductors are used for making very high speed computers.