Why copper,lead silver etc. r good conductor of electricity in comparision to other..?

well!!!

resistivity determined scattering of electrons. more scattering, higher resistance.

quantum mechanics states energy of electron in atom cannot arbitrary value. rather, there fixed energy levels electrons can occupy, , values in between these levels impossible. energy levels grouped 2 bands: valence band , conduction band (the latter above former). electrons in conduction band may move freely throughout substance in presence of electrical field.

reasons extremely low resistivity (high conductivity) of metals, "the metallic substances differ other materials fact outer shells of atoms bound rather loosely, , let 1 of electrons go free (conduction band). interior of metal filled large number of unattached electrons travel aimlessly . when metal wire subjected electric force applied on opposite ends, these free electrons rush in direction of force, forming call electric current."

but, in insulators , semiconductors, atoms in substance influence each other between valence band , conduction band there exists forbidden band of energy levels, electrons cannot occupy. in order current flow, relatively large amount of energy must furnished electron leap across forbidden gap , conduction band. thus, large voltages can yield relatively small currents.

or in other words, why there resistive power less other one.

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