Series and Parallell circuits

• Circuit: Individual electronic components connected by conductive wires that an electrical current can flow through
• Basic components of a circuit

  1. Power Source
  2. Energy using component
  3. Connecting wires
  4. Switches
• Series circuit

  • A circuit with only one pathway for electricity to flow from the source, to all the loads and back to the source
  • All of the currents in the circuit must flow through all of the load
  • The electricity flows from negative to positive as the opposites are attracted to each other and electrons are negatively charged
  • If one bulb blows, the rest will stop glowing as the current cannot flow through
• Parallel Circuit


  • A circuit with more than one pathway for electricity to flow
  • Electricity flows from negative to positive, just like in a series circuit
  • Depending on where the switches are located on the circuit, they may control one or both lightbulbs
  • The voltage is equal across parallel elements
  • If one bulb blows, the rest will keep glowing
• An open circuit is when a switch is OFF so current cannot flow.
• A closed circuit when a switch is ON so current can flow
• Electrical symbols are used to draw circuit diagrams as they are easier to interpret
• Common Electrical Symbols 1

  • Note: batteries are also known as cells

  
• Common Electrical Symbols 2

  • Note: Resistors are used to limit or regulate the flow of electrical currents

  
• The lightbulbs in a series circuit will become dimmer the more lightbulbs are added – this increases total resistance and decreases total current. Since the current passing through each light bulb is now reduced, it becomes dimmer.
• Ammeter

  • Measures the electric current (amps)
  • Measured by the number of electrons that travel through a wire in 1 second
  • Must NOT be connected to a voltage source
  • The ammeter will have the same reading at any point on the circuit
• Voltmeter

  • A voltmeter measures electrical voltage (volts) - pressure from the power source
  • It must be connected in parallel to the device
  • SERIES circuits SHARE voltage