series vs. parallel

A basic electrical circuit consisting of just one battery and one load resistance(ex. LED) are very simple to analyze, but the basic circuit is not often found in practical applications. Usually, we find circuits where more than two components are connected together.

Series Circuits
The basic idea of a "series" connection is that components are connected end-to-end in a line to form a single path for electrons to flow. A series circuit allows electrons to follow only one path. The loads(LEDs, resisters) in a series circuit must share the available voltage. In other words, each load in a series circuit will use up some portion of the voltage, leaving less for the next load in the circuit. This means that the light, heat, or sound given off by the device will be reduced.

Parallel Circuits
The basic idea of a "parallel" connection, on the other hand, is that all components are connected across each other's leads. In parallel circuits, the electric current can follow more than one path to return to the source, so it splits up among all the available paths. Across all the paths in a parallel circuit the voltage is the same, so each device will produce its full output.

In a series circuit, when one of the bulbs or one of the wires is left open or is broken, the entire circuit ceases. The break opens the circuit. Less expensive Christmas lights are usually of this type, and you have to search for the defective bulb. A parallel circuit is designed so that if one branch is defective, the flow of electricity will not be broken to the other branches.