Mesh: A loop that does not enclose another loop inside it. Mesh current: An imaginary current that flows around a mesh with the same value and direction regardless of the physical branch currents.
In KVL equations, voltage-drops are taken to be positive while voltage-rises are taken to be negative. When we encounter a resistor, we assume a voltage-drop in the direction of our movement over ther resistor.
For a circuit with N meshes,
- Draw and label mesh currents
- Write Kirchhoff’s Laws around each mesh
- Use Ohm’s Law to express the voltages in terms of mesh currents, using the relations between mesh currents and branch currents
- Solve the resulting set of N linear equations for the unknown N mesh currents
A supermesh is a combined two or more meshes to form a loop such that it does not pass through a current source.