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Plz explain causes of conductance in solids:












Plz explain causes of conductance in solids:

Grade:11

1 Answers

askIITIians Expert
21 Points
14 years ago

Causes of Conductance in Solids:

(i)                  In most of the solids, conduction is through electron movement under an electric field.

(ii)                In ionic solids conduction is by movement of ions.

(iii)               The magnitude of electrical conductivity strongly depends upon the number electrons available to take part in conduction process.

(iv)              In metals conduction strongly depends upon the number of electrons available per atom. The atomic orbitals form molecular orbitals which are too close in energy to each other so as to form a band.

(v)                If conduction band is not completely filled or it lies very close to a higher unoccupied band, then electrons can flow easily under an electric field thereby showing conductivity.

(vi)              In case of insulators, the gap between valence band and conduction band is too large, so electrons cannot jump from valence band to conduction band and very small conductivity is observed.

(vii)             In case of semiconductors, the gap between valence band and conduction band is small and therefore some of the electrons may jump from valence band to conduction band and some conductivity is observed.

(viii)           Electrical conductivity of semiconductors increases, with increase in temperature. This is due to the fact that with increase in temperature, large number of valence electrons from the valence band can jump to conduction band. Pure substances like silicon and germanium that exhibit this type of conducting behavior are called intrinsic semiconductors.

(ix)               For particle purposes, the conductivity of pure silicon and germanium is too low at room temperature, therefore there is need to increase the conductance by doping.

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