Comparing Series & Parallel Circuits (Edexcel GCSE Combined Science) : Revision Note

Series & Parallel Circuits

Current in Series & Parallel

• In a series circuit, the current is the same at all points

• In a parallel circuit, the current splits at junctions – some of it going one way and the rest going the other

Diagram showing the behaviour of current in series and parallel circuits

Potential Difference in Series & Parallel

• In a series circuit, the voltage of the power supply is shared between the components

• In a parallel circuit, the voltage across each component is the same

Diagram showing the behaviour of voltage in series and parallel circuits

Resistors in Series & Parallel

• In a series circuit, the total resistance is the sum of the resistance in each component

  • Two resistors in series will have a larger overall resistance than just one

  • This is because the charge has to push through multiple components when flowing around the circuit

  • The more components the charge has to travel through, the higher the number of collisions that occur

• In a parallel circuit, the total resistance decreases and is less than the resistance of any of the individual components

  • Two resistors in parallel will have a smaller overall resistance than just one

  • This is because the charge has more than one pathway to take, so only some charge will flow along each path

  • The more pathways there are, the smaller the amount of charge in each path

Series and Parallel Circuit Summary Table

The Design of Series Circuits

• A series circuit consists of a string of components connected in the same loop to a power supply

• In a series circuit:

  • The current is the same at all points around the loop

  • The potential difference of the power supply is shared between the individual components

• Two disadvantages of series circuits are:

  • If one of the components breaks, all of the others will stop working

  • The components cannot be controlled (switched on and off) separately

Construction of a simple series circuit with an ammeter, voltmeter, cell and resistor