Kirchhoff’s law

• Node - any point where 2 or more circuit elements are connected together.
• Branch - a circuit element connected between two nodes.
• Loop - a collection of branches that form a closed path returning to the same node without going through any other nodes or branches twice.
• Kirchhoff’s Current Law

  • No charge can accumulate at a junction or node; thus, the amount of charge entering the junction per unit time is equal to the amount of charge leaving per unit time.
• Kirchhoff’s Current Law

  • It follows CONSERVATION OF CHARGE.
• KCL

  I entering = I leaving
• Junction Rule

  • The sum of all currents entering a junction must equal the sum of all currents leaving the junction
• Loop Rule

  • Based upon conservation of energy the algebraic sum of voltages dropped (potential differences) across components around a loop is zero.
• Voltage Law Sign Conventions

  
  

  → = +

  ← = -

  
• Sign conventions for resistor

  opposite direction = +

  same direction = -
• Ohm’s Law is used to find some of the needed currents

  and voltages to solve the problems.