A.电流表A1(量程为500μA,内阻r1=1000Ω)
B.电流表A2(量程为0.3A,内阻约0.1Ω)
C.滑动变阻器R1(0~1000Ω,额定电流3A)
D.滑动变阻器R2(0~5Ω,额定电流1.0A)
E.滑动变阻器R3(0~1Ω,额定电流1.0A)
F.电阻箱R(阻值范围为0~9999.9Ω)
G.电源(电动势E=3.0V,内阻约0.2Ω)
H.开关S、导线若干