我们知道,电路图中连接用电器的导线的电阻是可忽略的,而在实际电路中,连接用电器的导线的电阻则不能忽略.并且导线的电阻与其长度成正比,由于欧姆定律反映的是部分电路中电流、电压、电阻三者之间的对应关系,因此,运用它可巧妙地求出长度.例1如图1所示,在乙处某施工工地接有一个电阻为 We know that the resistance of the wires connected to the electrical circuit in the circuit diagram is negligible, and in the actual circuit, the resistance of the wires connecting the appliances cannot be ignored. And the resistance of the wire is proportional to its length, because Ohm’s law reflects the part The correspondence among the current, voltage, and resistance in the circuit. Therefore, it can be used to calculate the length of the circuit. Example 1 As shown in Figure 1, there is a resistor connected to a construction site at site B.