节点法分析电路的原则:(1)把理想电流表看成短路;(2)把理想电压表看成断路;(3)把所有用导线相连的地方看作为同一个点(即中间任意地方不能有电阻);(4)整理电路,即按顺序把各点间的电阻画出.【例1】如图1所示,电阻R1=R2=R3=R4=R,试求AB间的有效电阻.分析:如图1所示,把所有用导线 The nodal method analyzes the principle of the circuit: (1) the ideal ammeter is regarded as a short circuit; (2) the ideal voltmeter is regarded as an open circuit; (3) all the places connected by wires are regarded as the same point (that is, no place in the middle can have Resistor); (4) organize the circuit, that is, draw the resistance between the points in order. [Example 1] As shown in Figure 1, the resistance R1 = R2 = R3 = R4 = R, try to find the effective resistance between AB. Analysis: As shown in Figure 1, take all the wires