Question

现要测电阻R₀阻值和干电池组的电动势E及内阻r．给定的器材有：两个理想电压表（量程均为3V），理想电流表（量程为0.6A），滑动变阻器R，待测的电阻R₀，两节串联的电池，电键S及导线若干．某同学设计一个如图（a）所示的电路同时测电阻R₀阻值和电池组的电动势及内阻，调节变阻器，两电压表和电流表分别测得多组U₁、U₂、I的读数，并作出U₁﹣I图（图线2）和U₂﹣I图（图线1），见图（b）．                                   

（1）由图可知得出电阻R₀阻值为                                                                  Ω，电池组E的电动势为             V，内阻为                                                                                                                    Ω．

（2）若上述电路中少了一个电压表，仍可用一个电路同时测电阻R₀阻值和干电池组的电动势E及内阻．请你在线框中画出电路图，并写出简单的实验步骤                                                                                    

实验步骤：①                                                                               

②                                                                                              

③                                                                                           

④                                                                                           ．                                

                                                                                                                                     

Answer 1

（1）4.0；3.0；2.0；

（2）①按电路图连接好电路；

②闭合开关S，移动滑片P使滑动变阻器短路，测得两电表读数为U₁、I₁；

③移动滑片P使滑动变阻器不短路，测得两电表读数为U₂、I₂；

④整理器材，数据处理．