Ohm’s law states that at a constant temperature, current I through a conductor between two points is directly proportional to the potential difference or voltage, V, across the two points.\xa0Thus, the ratio V: I is constant, and is called the resistance, R, of the conductor.\xa0In other words, V/I = constant = R, or V = IR, where R is a constant for the given metallic wire at a given temperature and is called its resistance.\xa0The S.I unit of Resistance is ohm.If the values of V are plotted against I on a graph paper, the graph is known as a V-I graph. As the temperature of a conductor rises, its resistance also increases.