Series and Parallel Circuits

In a series circuit, all components are connected in a line, one after the other. This means there is only one path for the electricity to flow.
If you remove or disconnect one component in a series circuit (like taking out one bulb from a string of Christmas lights), the entire circuit is broken and all electricity flow stops. This is because there is only one pathway in a series circuit.
The total or overall resistance of a series circuit is the sum of the individual resistances of each component. In other words, if you have two resistors with resistances of 5 Ω and 10 Ω, the total resistance of these two resistors in series would be 15 Ω (5 Ω + 10 Ω = 15 Ω).
A parallel circuit, unlike a series circuit, has components that are connected in parallel like rungs on a ladder. Electric current has more than one path it can take.
If you remove or disconnect a component from one parallel line, only that line within the parallel circuit is affected. Other lines and components continue to receive electricity and operate as normal. This is why house lights work independently of each other - they are wired in parallel.
The total resistance in a parallel circuit decreases as more branches are added. This is because there are more paths for current to flow through, so the overall resistance is less.
The voltage across each component in a parallel circuit is the same. This is a crucial point to remember. Electric potential (voltage) is constant across each path in a parallel circuit.
For parallel circuits, the total current flowing from the power supply equals the sum of the currents flowing through each parallel branch.
Ohm’s Law, named after its founder Georg Ohm, is a fundamental principle in series and parallel circuits. It states that the current (I) flowing in a circuit is directly proportional to the voltage (V) and inversely proportional to the resistance (R). The formula is I=V/R.
When calculating the total resistance in a series or parallel circuit, or determining the current, voltage, or resistance of a single component, you will use Ohm’s Law and the laws governing either series or parallel circuits.
Both series and parallel circuits are fundamental concepts for understanding how electricity behaves and are essential to the understanding of technologies from holiday lights to computer networks.

Remember to draw diagrams as you revise and practise some numerical questions on these topics to consolidate your understanding.