What are resistance and resistivity? Give their units.
Resistance: The ratio of the potential difference across the ends of a conductor to the current flowing through the conductor is called the resistance of the conductor. Its unit is Ohm( Ω)
Resistivity: The resistivity of a conductor is the resistance of the conductor of unit length and unit area of the cross-section at a constant temperature. Its unit is Ohm-meter (Ω-m).