Series and parallel circuits

• Series circuit


  A circuit with only one route for the electrical current
• Series circuit


  • The same current flows through both bulbs
  • The voltage of the power supply is shared between the components
• Investigating voltage in a series circuit

  1. Build a circuit

  2. Record voltage across components

  3. Change resistance and record new voltages

  4. Repeat until pattern is spotted
• In a series circuit, adding more components increases the total resistance
• The total resistance in a series circuit is equal to the sum of all the individual resistances
• Parallel circuit


  A circuit with more than one route for the electrical current
• Parallel circuit


  • Each bulb has the same voltage as the power supply
  • The total current through the circuit is the sum of the current in each separate route
• Investigating current in a parallel circuit

  1. Build a circuit

  2. Record current through each ammeter

  3. Change resistance and record new currents

  4. Repeat until pattern is spotted
• The resistance in a parallel circuit decreases as you add more components
• The total resistance in a parallel circuit is always less than the smallest resistance
• In Figure 1 the voltage of the cell is 2.0V. If the voltage across one bulb is 0.5V, the voltage across the second bulb can be determined
• A 150 resistor is placed in parallel with a 10Ω resistor. The voltage across the 150 resistor is 6V
• What is the voltage across the 100 resistor?
• What is the total resistance in the circuit?
• Types of circuits


  • Series circuit
  • Parallel circuit