Circuit Theory

According to Ohm's law, V = IR, the voltage across any two points of a node with negligible resistance is

{\displaystyle V=IR=I\cdot 0=0,}{\displaystyle V=IR=I\cdot 0=0,}

showing that the electric potential at every point of a node is the same.

There are some notable exceptions where the voltage difference is large enough to become significant:

High-precision resistance measurements using a Kelvin connection

The difference in voltage between ground and neutral, between the neutral wire and the ground in domestic AC power plugs and sockets, can be fatal. A properly installed electrical system connects them together at only one location, leading many people to the fatally incorrect conclusion that they are at "the same" voltage, or that the safety ground is "redundant and unnecessary"

The Seebeck effect and the Peltier effect

Joints involving aluminium wire

Dots used to mark nodes on a circuit diagram are sometimes referred to as meatballs.This is the main concept of circuit theory.