Notes: Kirchhoff's Second Law | Physics for Grade 10 PDF Download

Introduction

• Kirchhoff’s second law states that:
  • The sum of the e.m.f’s in a closed circuit equals the sum of the potential differences
• This is a consequence of conservation of energy
• Below is a circuit explaining Kirchhoff’s second law with the sum of the voltages in the closed series circuit equal to the sum of the e.m.f’s:
  Image captionThe sum of the voltages are equal to the sum of the e.m.f from the batteries
• In a series circuit, the voltage is split across all components depending on their resistance
  • The sum of the voltages is equal to the total e.m.f of the power supply
• In a parallel circuit, the voltage is the same across each closed loop
  • The sum of the voltages in each closed circuit loop is equal to the total e.m.f of the power supply:
    
• A closed circuit loop acts as its own independent series circuit and each one separates at a junction. A parallel circuit is made up of two or more of these loops
  Each circuit loops acts as a separate, independent series circuit
• This makes parallel circuits incredibly useful for home wiring systems: a single power source supplies all lights and appliances with the same voltage
• If one light breaks, voltage and current can still flow through for the rest of the lights and appliances