DC Circuits — Ohm's Law

Series and parallel resistors with live current visualization

Ohm's Law states that the current through a conductor is directly proportional to the voltage and inversely proportional to the resistance. In series circuits, resistors share the same current but split the voltage; the equivalent resistance is the sum of individual resistances. In parallel circuits, resistors share the same voltage but split the current; the reciprocal of equivalent resistance equals the sum of reciprocals. Understanding these two configurations is fundamental to analyzing any real-world circuit.