“伏安法”测电阻是中考的必考知识点.如何选用电流表和电压表的量程,是学生在实际操作过程中必须分析判断的.中学物理实验中用到的电流表和电压表均为双量程,即电流表的量程有“0-0.6 A”和“0-3 A”;电压表量程有“0～3 V”和“0-15 V”.不同的量程对 “Volt-ampere” test resistance is a must-know knowledge point in the examination. How to select the ammeter and voltmeter range is the student must analyze and judge during the actual operation. The ammeter and voltmeter used in middle school physics experiment are double The range, that is, the range of the current meter has “0-0.6 A” and “0-3 A”; the voltmeter range has “0 to 3 V” and “0-15 V”. Different range pairs