Potential Difference in Parallel Circuits

• Potential difference


  Tells us about energy transfers taking place in a circuit. One volt of potential difference means one Joule of energy is transferred for each Coulomb of charge moving through the circuit.
• In a series circuit, potential difference is split between components.
• Parallel circuits


  • Have branches, and some of the current passes through each branch.
• In a parallel circuit, the potential difference across each component is the same.
• Measuring potential difference in a parallel circuit

  1. Use a voltmeter to measure the potential difference across the cell

  2. Use a voltmeter to measure the potential difference across the branches
• Potential difference measurements in a parallel circuit

  • Potential difference across the top lamp is 6 volts
  • Potential difference across the bottom lamp is 6 volts
• When components are connected in parallel


  The potential difference across each component is the same
• Calculating potential difference in a parallel circuit

  • Potential difference across the top lamp is 12 volts
  • Potential difference across the bottom lamp is 12 volts
  • Potential difference across the cell is 12 volts
• Calculating potential difference in a more complicated parallel circuit

  1. Identify the two lamps in series in the bottom branch

  2. Recognize that the total potential difference across the bottom branch must be the same as the branch above

  3. Use the voltmeter readings to calculate the potential difference across the bottom lamp