distingish betwwen conductor and insulator on the basis of free charge and bound charge

Conductors: The substances having free charge carriers axe called the conductors. The examples of conductors are metallic substances e.g. copper, silver, gold, aluminum, iron, mercury etc.

The free and bound charges inside a conductor may be understood by the knowledge of structure of atom. Every substance is formed of atoms. Every atom is electrically neutral. It consists of a central, nucleus containing positive charge and negatively charged electrons revolving around the nucleus in various definite orbits. The electrons in orbits near the nucleus are tightly bound by Coulomb attractive forces; while the electrons in outermost orbit are very loosely bound. In metals these electrons are free and are not attached to individual atoms, but they can move freely throughout the volume of the metal and are often called the free electrons or free charges of the conductor / metal.

The absence of electron from a neutral atom makes it positively charged and the resulting atom is termed as positive ion. The positive ions are bound in the conductor in a regular pattern and are therefore termed as bound charges. Thus a conductor consists of free charges as well as bound charges. The free charges are free electrons and the bound charges are positive ions fixed in the lattice.

Insulators: The substances having no free charge carriers are called the insulators or dielectrics. The examples of insulators are glass, plastic, mica wood, cotton etc.

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Mukesh Sharma
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