Kirchhoff's Voltage Law

Kirchhoff's Voltage Law (KVL)

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Kirchhoff's Voltage Law (or Kirchhoff's Loop Rule) is a result of the electrostatic field being conservative. It states that the total voltage around a closed loop must be zero. If this were not the case, then when we travel around a closed loop, the voltages would be indefinite.

KVL example problem

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For the first loop (Battery, Element #1, Element #2)

-VB + V1 + V2 = 0

For the second loop (Element #2, Element #3, Element #4).  Note, you have to be careful with this one because you might not expect the voltage across Element #3 to be defined the way it is.

-V2 - V3 + V4 = 0

For the third loop (Battery, Element #1, Element #3, Element #4)

-VB + V1 - V3 + V4 = 0