Ans: Resistance and Resistivity: Resistance: It is the opposition offered by the conductor to the flow of current. Resistivity: It is property of the substance by virtue of which it opposes to the flow of current passing through it. The resistance of a specimen piece of material having unit length and unit cross sectional area is known as resistivity of that material.
Specific resistance or resistivity is defined as the resistance between the opposite faces of a meter cube of the material. Relationship between Resistance and Resistivity: Resistance = R = ρ ( l / a) Ω where, ρ = Resistivity of material in Ω-m. l = length of conductor in m. a = cross sectional area of conductor in m2 . Material having high resistivity: Mica, Nichrom, Rubber, Glass, Plastic Porcelain, Dry wood, Insulating material etc.