Why metals are good conductors of electricity?
Metals are excellent conductors because the atoms in a metal form a matrix through which their outer electrons can move freely. Instead of orbiting their respective metal atoms, they form a "sea" of electrons that surrounds the positively charged atomic nuclei of the interacting metal ions . The electrons then move freely throughout the electron sea.
In a copper wire when an external influence of electrons is passed, the electrons present in copper find it repulsive so they move away from each other.
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