Kirchhoff's Rules

Junction Rule

This section is about Kirchoff's first rule, the junction rule, which states that:

"The sum of the currents entering any junction must equal the sum of the currents leaving that junction" ???

If you have a circuit that splits into two or more paths (Parallel Circuit), this rule basically states that the current entering the paths is equal to the sum of the currents in each path, or mathematically:

$I_t=I_1+I_2$

Remember this rule only applies in Parallel Circuits.

This law is also called Kirchoff's Current Law (KCL).

Loop Rule

"The sum of the potential differences across all the elements around any closed circuit loop must be zero"

This statement may sound complicated but is basically stating that the incoming voltage is equal to the sum of the voltages at all the the different elements in a loop.

For example if the incoming voltage is 9V, and the voltage at the first resistor is 3V, and the voltage at the diode is 4V, then the voltage at the second resistor must be 2V.

Mathematically,

$V_t=(V_1+V_2+V_3...V_n$)

This law is also called Kirchoff's Voltage Law (KVL).