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A conductor is characterized by existence of free electrons . These are electrons in the outermost shells of atoms (the valence electrons) which get detatched from the parent atoms during the formation of metallic bonds and move freely in the entire medium in such way that the conductor becomes an equipotential volume.
In contrast, in dielectrics (insulators), the outer electrons remain bound to the atoms or molecules to which they belong. Both conductors and dielectric, on the whole, are charge neutral. However, in case of dielectrics, the charge neutrality is satisfied over much smaller regions (e.g. at molecular level). |
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A dielectric consists of molecules which remain locally charge neutral. The molecules may be polar or non-polar. In non-polar molecules, the charge centres of positive and negative charges coincide so that the net dipole moment of each molecule is zero. Carbon dioxide molecule is an example of a non-polar molecule.
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