如图所示,一个电阻箱和一个电流表串联在电路里.电阻箱上并联着一个电压表.改变电阻箱的电阻,分别得到“8 V,0.09 A;9 V,0.04 A”的示数.电源的内阻是_________.
20Ω
如图所示,一个电阻箱和一个电流表串联在电路里.电阻箱上并联着一个电压表.改变电阻箱的电阻,分别得到“8 V,0.09 A;9 V,0.04 A”的示数.电源的内阻是_________.
如图所示,一个电阻箱和一个电流表串联在电路里.电阻箱上并联着一个电压表.改变电阻箱的电阻,分别得到“8 V,0.09 A;9 V,0.04 A”的示数.电源的内阻是_________.
20Ω