Phân tích nút và phân tích lưới (mesh)

Nodal analysis: KCL does the walking

• Pick a reference node 参考节点 (ground), label the other node voltages, and write one KCL equation per node with currents as voltage differences over resistances. Nodal analysis 节点法 powers every circuit simulator.
• A voltage source tied to ground fixes one node outright; a floating one needs a supernode 超节点: wrap KCL around both ends and add $V_{P} - V_{Q} = V_{s}$.

{exercise:uni-ee13-node}

Mesh analysis: KVL around each window

• Give every window a clockwise mesh current 网孔电流 and write KVL per window; a shared resistor appears as $R(I_{1} - I_{2})$. Mesh analysis 网孔法 suits current sources and planar loops.
• Count equations for both methods and pick the smaller — method choice is part of the answer.

Two unknown nodes, one clean finish

• For chains like 12 V → 2 Ω → X → 4 Ω → Y → 6 Ω → ground with 1 A into Y, write both equations and clear fractions before solving.
• Verify through a node you did not use for the solve — the check is where errors die.

{exercise:uni-ee13-verify}

{exercise:uni-ee13-method}