A basic electrical circuit consists of three fundamental components: voltage, current, and resistance. Voltage is the electrical potential that drives current through the circuit. Current is the flow of electrons, and resistance opposes this flow. These three quantities are related by Ohm's Law: V equals I times R. Let's see how current flows through a simple circuit with a battery and resistor.
In a series circuit, components are connected end-to-end in a single path. This means there's only one route for current to flow through all components. The key characteristic is that the same current flows through every component. The total resistance equals the sum of individual resistances. When we add more resistors in series, the total resistance increases, which reduces the current flow through the entire circuit.
In a parallel circuit, components are connected across common points, creating multiple paths for current flow. Unlike series circuits, each component receives the same voltage from the source. The current splits at junctions and flows through each branch independently. The total current is the sum of currents through each branch. For resistance, we use the reciprocal formula: one over total resistance equals the sum of one over each individual resistance.
Let's compare series and parallel circuits side by side. In series circuits, current flows through a single path and remains the same everywhere, while voltage divides across components. Total resistance is the sum of individual resistances. In parallel circuits, current splits at junctions while voltage remains the same across all branches. Total resistance is calculated using the reciprocal formula. Series circuits are used in applications like Christmas lights, while parallel circuits are essential for household wiring where each device needs the same voltage.
Let's solve practical circuit problems. Given a 12-volt battery with three resistors of 4, 6, and 3 ohms, we'll calculate total resistance and current for both configurations. In series: total resistance is 4 plus 6 plus 3 equals 13 ohms, giving us a current of 0.92 amperes throughout. In parallel: using the reciprocal formula, total resistance is 1.33 ohms, resulting in a total current of 9 amperes that splits among the branches.