Ohm'law

Material that obeys Ohm's Law is called "ohmic" or "linear" because the potential difference across it varies linearly with the current.
3. Ohm's Law can be used to solve simple circuits. A complete circuit is one which is a closed loop. It contains at least one source of voltage (thus providing an increase of potential energy), and at least one potential drop i.e., a place where potential energy decreases. The sum of the voltages around a complete circuit is zero.