The foundational law governing this behavior is Ohm's Law, which states that the current flowing through a conductor is directly proportional to the potential difference across its ends, provided physical conditions like temperature remain constant. The constant of proportionality is resistance, the inherent opposition a material offers to the flow of current.
To analyze more complex electrical networks where simple laws fall short, we rely on Kirchhoff's Rules—one based on the conservation of charge (junction rule) and the other on the conservation of energy (loop rule). These principles form the basis for practical measuring instruments like the Wheatstone bridge, which are essential for accurately determining unknown resistances and managing power distribution in our daily electronics.