Solution

Substances which allow the electricity to flow through them have low resistivities are called good conductors. For example, metals have very low resistivity in the range of 10 m. Substances having moderate resistivity and offering significant resistance to the flow of electric current are called resistors. For example, alloys have moderate resistivity of the order of 100 m. Substances have very high resistivities and almost negligible conductivities; as they do not allow electric current to flow through them. For example, rubber and plastics have a high range of resistivity of the order of 10 ohm m.