在初三物理电学习题中,经常出现电路安全问题的计算,它是中考题中常见的知识考查点,也是学生感到棘手的问题,下面通过题型归类来说明一般解法要点.一、考虑电流表的量程例1 (99’福州)在图1中,R_1是0～50Ω的滑动变阻器,电流表A_1的量程是0～0.6A,A_2的量程是0～3A,电阻R_2=3.6Ω,电源电压为9V保持不变.闭合开关后,为了两电表都 In the third year of physical electricity learning problems, the calculation of circuit safety problems often occurs. It is a common knowledge examination point in the examination questions, and it is also a problem that students feel is intractable. The following points are used to illustrate the general solution points. I. Consider the ammeter Range Example 1 (99’Fuzhou) In Fig. 1, R_1 is a sliding varistor of 0-50Ω, the range of ammeter A_1 is 0-0.6A, the range of A_2 is 0-3A, the resistance R_2 is 3.6Ω, and the power supply voltage is 9V remains unchanged. After closing the switch, for both meters