Kirchoff’s Voltage Law

Gustav Kirchoff

The concept behind Kirchoff’s Voltage Law is that around any electrical loop, the sum of the voltage rises equals the sum of the voltage drops.  Another way to put this is that if you start at one point on a circuit and go around the circuit in a loop, when you come to a component where the voltage across the component increases, add the voltage, and when you come to a component where the voltage across the component decreases, subtract the voltage.  When you return back to the point your started at, your total should be at zero.

This is sort of like going for a hike in the mountains.  During your hike, you will sometimes be climbing upwards and sometimes be climbing downwards and sometimes be walking on the flat.  However, if you return back to where you started from, your net elevation gain is 0.

Kirchoff’s voltage law is basically a conservation of energy rule.  In a circuit, there are some things that provide electrical energy and some things that use electrical energy.  All of the energy from the sources must be used up by all of the loads in the electrical circuit.