Series and Parallel circuit

• In a series circuit, the current is always the same

  A1 = A2 = A3

  
• In a parallel circuit, the current is never 'used up'

  
• Parallel circuits - The current leaving + return to the power supply is the same ( A1 = A4 ). When the current arrives at a junction, it is split. So A2 = A3, the current in each branch adds up to the current leaving and returning to the power supply

  
• Parallel circuit : current has a choice. Potential difference is the same around the circuit, current splits but adds up to what you put in. Resistance is smaller than your lowest resistor.

  
• Series circuit : Current has no choice. Current is the same around the circuit, potential difference splits but adds up to what you put in. Resistance gets added together.