Electricity: Series and Parallel Circuits

Understanding Series Circuits

A series circuit has only one path for the electric current to flow through.
Total resistance in a series circuit is calculated by adding up the resistances of each component.
Current (I) in a series circuit is the same through each component. This is known as Kirchhoff’s current law.
The total voltage or potential difference (V) in a series circuit is the sum of the voltages across each component, which is often referred to as Kirchhoff’s voltage law.
If one component fails in a series circuit, all components will stop working because the circuit path is broken.

A parallel circuit has multiple paths for the current to flow through.
In a parallel circuit, the voltage across each component is the same and equals the supply voltage.
Total resistance in a parallel circuit can be calculated using the formula 1/Rt= 1/R1 + 1/R2 + 1/R3 …, where Rt is total resistance and R1, R2, R3 are the resistances of the parallel components.
Unlike in a series circuit, if one component fails in a parallel circuit, the other components will still work because current can still flow through other paths.

In a series circuit, intensity of the bulb and lifespan of the battery will depend upon the number of components in the circuit. More components result in a dimmer bulb and shorter battery life.
In a parallel circuit, the intensity of each bulb is unaffected by the addition of more bulbs and each bulb will shine as bright, but the battery life decreases as more paths are added for electric current.
In both series and parallel circuits, conservation of energy applies, meaning that the total input energy always equals the total output energy.

Many practical circuits, such as those in your home, are a combination of series and parallel circuits.
Household lighting is typically connected in parallel so that each light bulb receives the full mains voltage and they can be individually controlled.
Some Christmas lights are wired in series so when one bulb blows, all the lights go out.