Simple Circuits Curriculum

Section 5: Endnotes

• ¹ There can also be a split after the wire leaves the battery.
• ² Mathematically, the relationship of the resistances of individual bulbs in a circuit and the overall resistance of the entire circuit is very different for series and parallel circuits. In a series circuit, the overall resistance of the entire circuit is the sum of the resistances of each bulb in the circuit. In a parallel circuit, the overall resistance of the entire circuit is the sum of the reciprocals of the resistances of each bulb in the circuit. For a two-bulb circuit, where R₁ and R₂ are the resistances of the two bulbs, the resistance in the entire circuit is:
  

  Series: R_total = R₁ + R₂

  Parallel: R_total = 1/R₁ + 1/R₂