在恒定电流中有这样一类选择题:它需要确定电流或电压的大小,其四个选项都是可能数值.如果用定性分析法做,只能确定一个大致范围,不能找到最佳范围;如果定量计算来确定答案,不是求解相当麻烦,就是不知道从哪儿着手,有丈二的和尚摸不到头脑的感觉.如何快速求解最佳范围是一个值得研究的的 In the constant current there is such a multiple choice question: it needs to determine the size of the current or voltage, the four options are possible values.If done by qualitative analysis, can only determine a general range, can not find the best range; if Quantitative calculation to determine the answer, not to solve quite troublesome, that is, do not know where to start, there are Zhang monk touched the mind feeling .How to quickly solve the optimal range is a worthy of study