Parallel Circuits and Series Circuits

• Parallel Circuit


  • Power source and all components in multiple, separate loops
  • Two or more paths for electrons to follow
• Voltage in a parallel circuit

  Voltage across each pathway is the same as the voltage from the power source
• Voltage in a parallel circuit when switch is closed

  Voltmeters at each location will read the same voltage (6V)
• Adding batteries in parallel


  Has no effect on the total voltage because each electron in the circuit only passes through 1 battery
• Current in a parallel circuit


  Current coming out of the energy source is split/spread out to each pathway, then rejoins before returning to the energy source
• Current in a parallel circuit when switch is closed

  Ammeter readings: 0.2A, 0.1A, 4A, 0.2A, 0.1A
• Resistance in a parallel circuit

  Total resistance decreases when more loads are added
• We will NOT calculate the total resistance in a parallel circuit
• Electrons need a complete circuit to flow around and transfer energy to components
• Series circuit


  • Components connected in 1 path
• Parallel circuit


  • Components attached in many paths
• If a series circuit is broken

  Current will stop flowing and all components will stop working
• If a parallel circuit is broken


  Current will still flow through the other paths, so not all components will stop working
• If a switch is wired in series

  It can only complete/break the flow of electrons to everything at once (all on or all off)
• If a switch is wired in parallel


  It can complete/break the flow of electrons to components on 1 path without affecting the others (each is controlled separately)
• Voltage in a series circuit

  Total voltage from the energy source is divided between all loads
• Voltage in a parallel circuit


  Voltage is the same everywhere (same as energy source)
• Adding batteries in series

  Increases total voltage because each electron passes through them and gets multiple "pushes"
• Adding batteries in parallel

  Does not affect total voltage because each electron only passes through 1 battery (only gets "pushed" once)
• Current in a series circuit

  Current is the same everywhere
• Current in a parallel circuit

  Current leaves energy source and splits/rejoins at junctions between paths
• Series vs. Parallel Resistance simulation available
• Resistance in a series circuit


  Total resistance increases as more loads are added, calculated by adding the resistances together
• Resistance in a parallel circuit


  Total resistance decreases as more loads are added, we will not calculate the total resistance