Conductors insulators and semiconductors

Lecture General Physics 2 - Chapter 15: Electric Forces and Electric Fields. After studying this section will help you understand: first observations – greeks, properties of electric charges, conductors, insulators, semiconductors, charging by conduction,...

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If we connect a battery across a body, there is a movement of free electrons towards the positive end. This movement of electrons is an electric current. All materials can be classified into three groups according to how readily they permit an electric current to flow. These are: conductors, insulators, and semiconductors. In the first category are substances which provide an easy path for an electric current. All metals are conductors, however some metals do not conduct well. Manganin, for example, is a poor conductor. Copper is a good conductor, therefore it is widely used for cables.

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semiconductors.In the first category are substances which provide an easy path for an electric current. All metals are conductors, however some metals do not conduct well. Manganin, for example, is a poor conductor. Copper is a good conductor, therefore it is widely used for cables. A non-metal which conducts well is carbon. Salt water is an example of a liquid conductor. A material which does not easily release electrons is called an insulator. Rubber, nylon, porcelain and air are all insulator. There are no perfect insulators.

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Semiconductor Thermometers Classification of Semiconductor Thermometers Semiconductor thermometers (Sachse, 1975) are made from materials which are neither conductors nor insulators. Research of the thermal properties of semiconductors was first reported by William Faraday in 1834. Their industrial production was started at the Bell Telephone Company and, simultaneously, at Osram in 1930. It is apparent from the work of many authors such as Sze (1969) and van der Ziel (1968), among others, that these materials may have an intrinsic, or pure form, a compound form or a doped form.

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A semiconductor material has a resistivity lying between that of a conductor and that of an insulator. However, in contrast to the granular materials used for resistors, a semiconductor establishes its conduction properties through a complex quantum mechanical behavior within a periodic array of semiconductor atoms, i.e., within a crystalline structure.

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