Comparing Series & Parallel Circuits (OCR GCSE Physics A (Gateway Science Suite)): Revision Notes

2.2.3 Comparing Series & Parallel Circuits

Series circuits

• Components are connected end-to-end
• All the current flows through all the components
• Can only switch them all off at once
• The Potential difference is shared across the whole circuit. The PD of power supply = sum of PD across each component
• The current is the same through all parts of the circuit. The Current at one point = current at any other point
• Total Resistance is the sum of the resistance in each component
  • Resistance of two components is bigger than just one of them, because the charge has to push through both of them when flowing round the circuit

Parallel circuits

• Components are connected separately to the power supply
• Current flows through each one separately
• You can switch each component off individually
  • Potential difference is the same across all branches
  • PD of power supply = PD of each branch
  • Because charge can only pass through any one branch
  • Current is shared between each of the branches
  • Current through source = sum of current through each branch
  • Total resistance is less than the branch with the smallest resistance
  • Two resistors in parallel will have a smaller overall resistance than just one
  • Because charge has more than one branch to take, so only some charge will flow along each branch